The Descent Of Man
1871
THE DESCENT OF MAN
by Charles Darwin
INTRODUCTION
INTRODUCTION.
THE NATURE of the following work will be best understood by a
brief account of how it came to be written. During many years I
collected notes on the origin or descent of man, without any intention
of publishing on the subject, but rather with the determination not to
publish, as I thought that I should thus only add to the prejudices
against my views. It seemed to me sufficient to indicate, in the first
edition of my Origin of Species, that by this work "light would be
thrown on the origin of man and his history"; and this implies that
man must be included with other organic beings in any general
conclusion respecting his manner of appearance on this earth. Now
the case wears a wholly different aspect. When a naturalist like
Carl Vogt ventures to say in his address as President of the
National Institution of Geneva (1869), "personne, en Europe au
moins, n'ose plus soutenir la creation independante et de toutes
pieces, des especes," it is manifest that at least a large number of
naturalists must admit that species are the modified descendants of
other species; and this especially holds good with the younger and
rising naturalists. The greater number accept the agency of natural
selection; though some urge, whether with justice the future must
decide, that I have greatly overrated its importance. Of the older and
honoured chiefs in natural science, many unfortunately are still
opposed to evolution in every form.
In consequence of the views now adopted by most naturalists, and
which will ultimately, as in every other case, be followed by others
who are not scientific, I have been led to put together my notes, so
as to see how far the general conclusions arrived at in my former
works were applicable to man. This seemed all the more desirable, as I
had never deliberately applied these views to a species taken
singly. When we confine our attention to any one form, we are deprived
of the weighty arguments derived from the nature of the affinities
which connect together whole groups of organisms- their geographical
distribution in past and present times, and their geological
succession. The homological structure, embryological development,
and rudimentary organs of a species remain to be considered, whether
it be man or any other animal, to which our attention may be directed;
but these great classes of facts afford, as it appears to me, ample
and conclusive evidence in favour of the principle of gradual
evolution. The strong support derived from the other arguments should,
however, always be kept before the mind.
The sole object of this work is to consider, firstly, whether man,
like every other species, is descended from some pre-existing form;
secondly, the manner of his development; and thirdly, the value of the
differences between the so-called races of man. As I shall confine
myself to these points, it will not be necessary to describe in detail
the differences between the several races- an enormous subject which
has been fully discussed in many valuable works. The high antiquity of
man has recently been demonstrated by the labours of a host of eminent
men, beginning with M. Boucher de Perthes; and this is the
indispensable basis for understanding his origin. I shall,
therefore, take this conclusion for granted, and may refer my
readers to the admirable treatises of Sir Charles Lyell, Sir John
Lubbock, and others. Nor shall I have occasion to do more than to
allude to the amount of difference between man and the
anthropomorphous apes; for Prof. Huxley, in the opinion of most
competent judges, has conclusively shewn that in every visible
character man differs less from the higher apes, than these do from
the lower members of the same order of primates.
This work contains hardly any original facts in regard to man; but
as the conclusions at which I arrived, after drawing up a rough draft,
appeared to me interesting, I thought that they might interest others.
It has often and confidently been asserted, that man's origin can
never be known: but ignorance more frequently begets confidence than
does knowledge: it is those who know little, and not those who know
much, who so positively assert that this or that problem will never be
solved by science. The conclusion that man is the co-descendant with
other species of some ancient, lower, and extinct form, is not in
any degree new. Lamarck long ago came to this conclusion, which has
lately been maintained by several eminent naturalists and
philosophers; for instance, by Wallace, Huxley, Lyell, Vogt,
Lubbock, Buchner, Rolle, &c.,* and especially by Haeckel. This last
naturalist, besides his great work, Generelle Morphologie (1866),
has recently (1868, with a second edit. in 1870), published his
Naturliche Schopfungsgeschichte, in which he fully discusses the
genealogy of man. If this work had appeared before my essay had been
written, I should probably never have completed it. Almost all the
conclusions at which I have arrived I find confirmed by this
naturalist, whose knowledge on many points is much fuller than mine.
Wherever I have added any fact or view from Prof. Haeckel's
writings, I give his authority in the text; other statements I leave
as they originally stood in my manuscript, occasionally giving in
the foot-notes references to his works, as a confirmation of the
more doubtful or interesting points.
* As the works of the first-named authors are so well known, I
need not give the titles; but as those of the latter are less well
known in England, I will give them:- Sechs Vorlesungen uberdie
Darwin'sche Theorie: zweite Auflage, 1868, von Dr. L. Buchner;
translated into French under the title Conferences sur la Theorie
Darwinienne, 1869. Der Mensch, im Lichte der Darwin'schen Lehre, 1865,
von Dr. F. Rolle. I will not attempt to give references to all the
authors who have taken the same side of the question. Thus G.
Canestrini has published (Annuario della Soc. dei Naturalisti, Modena,
1867, p. 81) a very curious paper on rudimentary characters, as
bearing on the origin of man. Another work has (1869) been published
by Dr. Francesco Barrago, bearing in Italian the title of "Man, made
in the image of God, was also made in the image of the ape."
During many years it has seemed to me highly probable that sexual
selection has played an important part in differentiating the races of
man; but in my Origin of Species I contented myself by merely alluding
to this belief. When I came to apply this view to man, I found it
indispensable to treat the whole subject in full detail.* Consequently
the second part of the present work, treating of sexual selection, has
extended to an inordinate length, compared with the first part; but
this could not be avoided.
* Prof. Haeckel was the only author who, at the time when this
work first appeared, had discussed the subject of sexual selection,
and had seen its full importance, since the publication of the Origin;
and this he did in a very able manner in his various works.
I had intended adding to the present volumes an essay on the
expression of the various emotions by man and the lower animals. My
attention was called to this subject many years ago by Sir Charles
Bell's admirable work. This illustrious anatomist maintains that man
is endowed with certain muscles solely for the sake of expressing
his emotions. As this view is obviously opposed to the belief that man
is descended from some other and lower form, it was necessary for me
to consider it. I likewise wished to ascertain how far the emotions
are expressed in the same manner by the different races of man. But
owing to the length of the present work, I have thought it better to
reserve my essay for separate publication.
PART ONE
DESCENT OR ORIGIN OF MAN
CHAPTER I.
THE EVIDENCE OF THE DESCENT OF MAN FROM SOME LOWER FORM.
HE WHO wishes to decide whether man is the modified descendant of
some pre-existing form, would probably first enquire whether man
varies, however slightly, in bodily structure and in mental faculties;
and if so, whether the variations are transmitted to his offspring
in accordance with the laws which prevail with the lower animals.
Again, are the variations the result, as far as our ignorance
permits us to judge, of the same general causes, and are they governed
by the same general laws, as in the case of other organisms; for
instance, by correlation, the inherited effects of use and disuse,
&c.? Is man subject to similar malconformations, the result of
arrested development, of reduplication of parts, &c., and does he
display in any of his anomalies reversion to some former and ancient
type of structure? It might also naturally be enquired whether man,
like so many other animals, has given rise to varieties and sub-races,
differing but slightly from each other, or to races differing so
much that they must be classed as doubtful species? How are such races
distributed over the world; and how, when crossed, do they react on
each other in the first and succeeding generations? And so with many
other points.
The enquirer would next come to the important point, whether man
tends to increase at so rapid a rate, as to lead to occasional
severe struggles for existence; and consequently to beneficial
variations, whether in body or mind, being preserved, and injurious
ones eliminated. Do the races or species of men, whichever term may be
applied, encroach on and replace one another, so that some finally
become extinct? We shall see that all these questions, as indeed is
obvious in respect to most of them, must be answered in the
affirmative, in the same manner as with the lower animals. But the
several considerations just referred to may be conveniently deferred
for a time: and we will first see how far the bodily structure of
man shows traces, more or less plain, of his descent from some lower
form. In succeeding chapters the mental powers of man, in comparison
with those of the lower animals, will be considered.
The Bodily Structure of Man. It is notorious that man is constructed
on the same general type or model as other mammals. All the bones in
his skeleton can be compared with corresponding bones in a monkey,
bat, or seal. So it is with his muscles, nerves, blood-vessels and
internal viscera. The brain, the most important of all the organs,
follows the same law, as shewn by Huxley and other anatomists.
Bischoff,* who is a hostile witness, admits that every chief fissure
and fold in the brain of man has its analogy in that of the orang; but
he adds that at no period of development do their brains perfectly
agree; nor could perfect agreement be expected, for otherwise their
mental powers would have been the same. Vulpian*(2) remarks: "Les
differences reelles qui existent entre l'encephale de l'homme et celui
des singes superieurs, sont bien minimes. It ne faut pas se faire
d'illusions a cet egard. L'homme est bien plus pres des singes
anthropomorphes par les caracteres anatomiques de son cerveau que
ceux-ci ne le sont non seulement des autres mammiferes, mais meme de
certains quadrumanes, des guenons et des macaques." But it would be
superfluous here to give further details on the correspondence between
man and the higher mammals in the structure of the brain and all other
parts of the body.
* Grosshirnwindungen des Menschen, 1868, s. 96. The conclusions of
this author, as well as those of Gratiolet and Aeby, concerning the
brain, will be discussed by Prof. Huxley in the appendix.
*(2) Lec. sur la Phys., 1866, p. 890, as quoted by M. Dally, L'Ordre
des Primates et le Transformisme, 1868, p. 29.
It may, however, be worth while to specify a few points, not
directly or obviously connected with structure, by which this
correspondence or relationship is well shewn.
Man is liable to receive from the lower animals, and to
communicate to them, certain diseases, as hydrophobia, variola, the
glanders, syphilis, cholera, herpes, &c.;* and this fact proves the
close similarity*(2) of their tissues and blood, both in minute
structure and composition, far more plainly than does their comparison
under the best microscope, or by the aid of the best chemical
analysis. Monkeys are liable to many of the same non-contagious
diseases as we are; thus Rengger,*(3) who carefully observed for a
long time the Cebus azarae in its native land, found it liable to
catarrh, with the usual symptoms, and which, when often recurrent, led
to consumption. These monkeys suffered also from apoplexy,
inflammation of the bowels, and cataract in the eye.The younger ones
when shedding their milk-teeth often died from fever. Medicines
produced the same effect on them as on us. Many kinds of monkeys
have a strong taste for tea, coffee, and spirituous liquors: they will
also, as I have myself seen, smoke tobacco with pleasure.*(4) Brehm
asserts that the natives of north-eastern Africa catch the wild
baboons by exposing vessels with strong beer, by which they are made
drunk. He has seen some of these animals, which he kept in
confinement, in this state; and he gives a laughable account of
their behaviour and strange grimaces. On the following morning they
were very cross and dismal; they held their aching heads with both
hands, and wore a most pitiable expression: when beer or wine was
offered them, they turned away with disgust, but relished the juice of
lemons.*(5) An American monkey, an Ateles, after getting drunk on
brandy, would never touch it again, and thus was wiser than many
men. These trifling facts prove how similar the nerves of taste must
be in monkeys and man, and how similarly their whole nervous system is
affected.
* Dr. W. Lauder Lindsay has treated this subject at some length in
the Journal of Mental Science, July, 1871: and in the Edinburgh
Veterinary Review, July, 1858.
*(2) A reviewer has criticised (British Quarterly Review, Oct. 1,
1871, p. 472) what I have here said with much severity and contempt:
but as I do not use the term identity, I cannot see that I am
greatly in error. There appears to me a strong analogy between the
same infection or contagion producing the same result, or one
closely similar, in two distinct animals, and the testing of two
distinct fluids by the same chemical reagent.
*(3) Naturgeschichte der Saugethiere von Paraguay, 1830, s. 50.
*(4) The same tests are common to some animals much lower in the
scale. Mr. A. Nicols informs me that he kept in Queensland, in
Australia, three individuals of the Phaseolarctus cinereus, and
that, without having been taught in any way, they acquired a strong
taste for rum, and for smoking tobacco.
*(5) Brehm, Illustriertes Thierleben, B. i., 1864, 75, 86. On the
Ateles, s. 105. For other analogous statements, see ss. 25, 107.
Man is infested with internal parasites, sometimes causing fatal
effects; and is plagued by external parasites, all of which belong
to the same genera or families as those infesting other mammals, and
in the case of scabies to the same species.* Man is subject, like
other mammals, birds, and even insects,*(2) to that mysterious law,
which causes certain normal processes, such as gestation, as well as
the maturation and duration of various diseases, to follow lunar
periods. His wounds are repaired by the same process of healing; and
the stumps left after the amputation of his limbs, especially during
an early embryonic period, occasionally possess some power of
regeneration, as in the lowest animals.*(3)
* Dr. W. Lauder Lindsay, Edinburgh Veterinary Review, July, 1858, p.
13.
*(2) With respect to insects see Dr. Laycock, "On a General Law of
Vital Periodicity," British Association, 1842. Dr. Macculloch,
Silliman's North American Journal of Science, vol. xvii., p. 305,
has seen a dog suffering from tertian ague. Hereafter I shall return
to this subject.
*(3) I have given the evidence on this head in my Variation of
Animals and Plants under Domestication, vol. ii., p. 15, and more
could be added.
The whole process of that most important function, the
reproduction of the species, is strikingly the same in all mammals,
from the first act of courtship by the male,* to the birth and
nurturing of the young. Monkeys are born in almost as helpless a
condition as our own infants; and in certain genera the young differ
fully as much in appearance from the adults, as do our children from
their full-grown parents.*(2) It has been urged by some writers, as an
important distinction, that with man the young arrive at maturity at a
much later age than with any other animal: but if we look to the races
of mankind which inhabit tropical countries the difference is not
great, for the orang is believed not to be adult till the age of
from ten to fifteen years.*(3) Man differs from woman in size,
bodily strength, hairiness, &c., as well as in mind, in the same
manner as do the two sexes of many mammals. So that the correspondence
in general structure, in the minute structure of the tissues, in
chemical composition and in constitution, between man and the higher
animals, especially the anthropomorphous apes, is extremely close.
* Mares e diversis generibus Quadrumanorum sine dubio dignoscunt
feminas humanas a maribus. Primum, credo, odoratu, postea aspectu. Mr.
Youatt, qui diu in Hortis Zoologicis (Bestiariis) medicus animalium
erat, vir in rebus observandis cautus et sagax, hoc mihi certissime
probavit, et curatores ejusdem loci et alii e ministirs
confirmaverunt. Sir Andrew Smith et Brehm notabant idem in
Cynocephalo. Illustrissimus Cuvier etiam narrat multa de hac re, qua
ut opinor, nihil turpius potest indicari inter omnia hominibus et
Quadrumanis communia. Narrat enim Cynocephalum quendam in furorem
incidere aspectu feminarum aliquarem, sed nequaquam accendi tanto
furore ab omnibus. Semper eligebat juniores, et dignoscebat in
turba, et advocabat voce gestuque.
*(2) This remark is made with respect to Cynocephalus and the
anthropomorphous apes by Geoffroy Saint-Hilaire and F. Cuvier,
Histoire Nat. des Mammiferes, tom. i., 1824.
*(3) Huxley, Man's Place in Nature, 1863, p. 34.
Embryonic Development. Man is developed from an ovule, about the
125th of an inch in diameter, which differs in no respect from the
ovules of other animals. The embryo itself at a very early period
can hardly be distinguished from that of other members of the
vertebrate kingdom. At this period the arteries run in arch-like
branches, as if to carry the blood to branchiae which are not
present in the higher Vertebrata, though the slits on the sides of the
neck still remain (see f, g, fig. 1), marking their former position.
At a somewhat later period, when the extremities are developed, "the
feet of lizards and mammals," as the illustrious von Baer remarks,
"the wings and feet of birds, no less than the hands and feet of
man, all arise from the same fundamental form." It is, says Prof.
Huxley,* "quite in the later stages of development that the young
human being presents marked differences from the young ape, while
the latter departs as much from the dog in its developments, as the
man does. Startling as this last assertion may appear to be, it is
demonstrably true."
* Man's Place in Nature, 1863, p. 67.
As some of my readers may never have seen a drawing of an embryo,
I have given one of man and another of a dog, at about the same
early stage of development, carefully copied from two works of
undoubted accuracy.*
* The human embryo (see upper fig.) is from Ecker, Icones Phys.,
1851-1859, tab. xxx., fig. 2. The drawing of this embryo is much
magnified. The embryo of the dog is from Bischoff,
Entwicklungsgeschichte des Hunde-Eies, 1845, tab. xi., fig. 42 B. This
drawing is magnified, the embryo being twenty-five days old. The
internal viscera have been omitted, and the uterine appendages in both
drawings removed. I was directed to these figures by Prof. Huxley,
from whose work, Man's Place in Nature, the idea of giving them was
taken. Haeckel has also given analogous drawings in his
Schopfungsgeschichte.
After the foregoing statements made by such high authorities, it
would be superfluous on my part to give a number of borrowed
details, shewing that the embryo of man closely resembles that of
other mammals. It may, however, be added, that the human embryo
likewise resembles certain low forms when adult in various points of
structure. For instance, the heart at first exists as a simple
pulsating vessel; the excreta are voided through a cloacal passage;
and the os coccyx projects like a true extending considerably beyond
the rudimentary legs."* In the embryos of all air-breathing
vertebrates, certain glands, called the corpora Wolffiana,
correspond with, and act like the kidneys of mature fishes.*(2) Even
at a later embryonic period, some striking resemblances between man
and the lower animals may be observed. Bischoff says "that the
convolutions of the brain in a human foetus at the end of the
seventh month reach about the same stage of development as in a baboon
when adult."*(3) The great toe, as Professor Owen remarks,*(4)
"which forms the fulcrum when standing or walking, is perhaps the most
characteristic peculiarity in the human structure"; but in an
embryo, about an inch in length, Prof. Wyman*(5) found "that the great
toe was shorter than the others; and, instead of being parallel to
them, projected at an angle from the side of the foot, thus
corresponding with the permanent condition of this part in the
Quadrumana." I will conclude with a quotation from Huxley,*(6) who,
after asking does man originate in a different way from a dog, bird,
frog or fish, says, "The reply is not doubtful for a moment; without
question, the mode of origin, and the early stages of the
development of man, are identical with those of the animals
immediately below him in the scale: without a doubt in these respects,
he is far nearer to apes than the apes are to the dog."
* Prof. Wyman in Proceedings of the American Academy of Sciences,
vol. iv., 1860, p. 17.
*(2) Owen, Anatomy of Vertebrates, vol. i., p. 533.
*(3) Die Grosshirnwindungen des Menschen 1868, s. 95.
*(4) Anatomy of Vertebrates, vol. ii., p. 553.
*(5) Proc. Soc. Nat. Hist., Boston, 1863, vol. ix., p. 185.
*(6) Man's Place in Nature, p. 65.
Rudiments. This subject, though not intrinsically more important
than the two last, will for several reasons be treated here more
fully.* Not one of the higher animals can be named which does not bear
some part in a rudimentary condition; and man forms no exception to
the rule. Rudimentary organs must be distinguished from those that are
nascent; though in some cases the distinction is not easy. The
former are either absolutely useless, such as the mammee of male
quadrupeds, or the incisor teeth of ruminants which never cut
through the gums; or they are of such slight service to their
present possessors, that we can hardly suppose that they were
developed under the conditions which now exist. Organs in this
latter state are not strictly rudimentary, but they are tending in
this direction. Nascent organs, on the other hand, though not fully
developed, are of high service to their possessors, and are capable of
further development. Rudimentary organs are eminently variable; and
this is partly intelligible, as they are useless, or nearly useless,
and consequently are no longer subjected to natural selection. They
often become wholly suppressed. When this occurs, they are
nevertheless liable to occasional reappearance through reversion- a
circumstance well worthy of attention.
* I had written a rough copy of this chapter before reading a
valuable paper, "Caratteri rudimentali in ordine all' origine dell'
uomo" (Annuario della Soc. d. Naturalisti, Modena, 1867, p. 81), by G.
Canestrini, to which paper I am considerably indebted. Haeckel has
given admirable discussions on this whole subject, under the title
of "Dysteleology," in his Generelle Morphologie and
Shopfungsgeschichte.
The chief agents in causing organs to become rudimentary seem to
have been disuse at that period of life when the organ is chiefly used
(and this is generally during maturity), and also inheritance at a
corresponding period of life. The term "disuse" does not relate merely
to the lessened action of muscles, but includes a diminished flow of
blood to a part or organ, from being subjected to fewer alternations
of pressure, or from becoming in any way less habitually active.
Rudiments, however, may occur in one sex of those parts which are
normally present in the other sex; and such rudiments, as we shall
hereafter see, have often originated in a way distinct from those here
referred to. In some cases, organs have been reduced by means of
natural selection, from having become injurious to the species under
changed habits of life. The process of reduction is probably often
aided through the two principles of compensation and economy of
growth; but the later stages of reduction, after disuse has done all
that can fairly be attributed to it, and when the saving to be
effected by the economy of growth would be very small,* are
difficult to understand. The final and complete suppression of a part,
already useless and much reduced in size, in which case neither
compensation or economy can come into play, is perhaps intelligible by
the aid of the hypothesis of pangenesis. But as the whole subject of
rudimentary organs has been discussed and illustrated in my former
works,*(2) I need here say no more on this head.
* Some good criticisms on this subject have been given by Messrs.
Murie and Mivart, in Transactions, Zoological Society, 1869, vol.
vii., p. 92.
*(2) Variation of Animals and Plants under Domestication, vol. ii
pp. 317 and 397. See also Origin of Species.(OOS)
Rudiments of various muscles have been observed in many parts of the
human body;* and not a few muscles, which are regularly present in
some of the lower animals can occasionally be detected in man in a
greatly reduced condition. Every one must have noticed the power which
many animals, especially horses, possess of moving or twitching
their skin; and this is effected by the panniculus carnosus.
Remnants of this muscle in an efficient state are found in various
parts of our bodies; for instance, the muscle on the forehead, by
which the eyebrows are raised. The platysma myoides, which is well
developed on the neck, belongs to this system. Prof. Turner, of
Edinburgh, has occasionally detected, as he informs me, muscular
fasciculi in five different situations, namely in the axillae, near
the scapulae, &c., all of which must be referred to the system of
the panniculus. He has also shewn*(2) that the musculus sternalis or
sternalis brutorum, which is not an extension of the rectus
abdominalis, but is closely allied to the panniculus, occurred in
the proportion of about three per cent. in upward of 600 bodies: he
adds, that this muscle affords "an excellent illustration of the
statement that occasional and rudimentary structures are especially
liable to variation in arrangement."
* For instance, M. Richard (Annales des Sciences Nat., 3d series,
Zoolog., 1852, tom. xviii., p. 13) describes and figures rudiments
of what he calls the "muscle pedieux de la main," which he says is
sometimes "infiniment petit." Another muscle, called "le tibial
posterieur," is generally quite absent in the hand, but appears from
time to time in a more or less rudimentary condition.
*(2) Prof. W. Turner, Proceedings of the Royal Society of Edinburgh,
1866-67, p. 65.
Some few persons have the power of contracting the superficial
muscles on their scalps; and these muscles are in a variable and
partially rudimentary condition. M.A. de Candolle has communicated
to me a curious instance of the long-continued persistence or
inheritance of this power, as well as of its unusual development. He
knows a family, in which one member, the present head of the family,
could, when a youth, pitch several heavy books from his head by the
movement of the scalp alone; and he won wagers by performing this
feat. His father, uncle, grandfather, and his three children possess
the same power to the same unusual degree. This family became
divided eight generations ago into two branches; so that the head of
the above-mentioned branch is cousin in the seventh degree to the head
of the other branch. This distant cousin resides in another part of
France; and on being asked whether he possessed the same faculty,
immediately exhibited his power. This case offers a good
illustration how persistent may be the transmission of an absolutely
useless faculty, probably derived from our remote semi-human
progenitors; since many monkeys have, and frequently use the power, of
largely moving their scalps up and down.*
* See my Expression of the Emotions in Man and Animals, 1872, p.
144.
The extrinsic muscles which serve to move the external ear, and
the intrinsic muscles which move the different parts, are in a
rudimentary condition in man, and they all belong to the system of the
panniculus; they are also variable in development, or at least in
function. I have seen one man who could draw the whole ear forwards;
other men can draw it upwards; another who could draw it backwards;*
and from what one of these persons told me, it is probable that most
of us, by often touching our ears, and thus directing our attention
towards them, could recover some power of movement by repeated trials.
The power of erecting and directing the shell of the ears to the
various points of the compass, is no doubt of the highest service to
many animals, as they thus perceive the direction of danger; but I
have never heard, on sufficient evidence, of a man who possessed
this power, the one which might be of use to him. The whole external
shell may be considered a rudiment, together with the various folds
and prominences (helix and anti-helix, tragus and anti-tragus, &c.)
which in the lower animals strengthen and support the ear when
erect, without adding much to its weight. Some authors, however,
suppose that the cartilage of the shell serves to transmit
vibrations to the acoustic nerve; but Mr. Toynbee,*(2) after
collecting all the known evidence on this head, concludes that the
external shell is of no distinct use. The ears of the chimpanzee and
orang are curiously like those of man, and the proper muscles are
likewise but very slightly developed.*(3) I am also assured by the
keepers in the Zoological Gardens that these animals never move or
erect their ears; so that they are in an equally rudimentary condition
with those of man, as far as function is concerned. Why these animals,
as well as the progenitors of man, should have lost the power of
erecting their ears, we can not say. It may be, though I am not
satified with this view, that owing to their arboreal habits and great
strength they were but little exposed to danger, and so during a
lengthened period moved their ears but little, and thus gradually lost
the power of moving them. This would be a parallel case with that of
those large and heavy birds, which, from inhabiting oceanic islands,
have not been exposed to the attacks of beasts of prey, and have
consequently lost the power of using their wings for flight. The
inability to move the ears in man and several apes is, however, partly
compensated by the freedom with which they can move the head in a
horizontal plane, so as to catch sounds from all directions. It has
been asserted that the ear of man alone possesses a lobule; but "a
rudiment of it is found in the gorilla";*(4) and, as I hear from Prof.
Preyer, it is not rarely absent in the negro.
* Canestrini quotes Hyrtl. (Annuario della Soc. dei Naturalisti,
Modena, 1897, p. 97) to the same effect.
*(2) The Diseases of the Ear, by J. Toynbee, F. R. S., 1860, p.
12. A distinguished physiologist, Prof. Preyer, informs me that he had
lately been experimenting on the function of the shell of the ear, and
has come to nearly the same conclusion as that given here.
*(3) Prof. A. Macalister, Annals and Magazine of Natural History,
vol. vii., 1871, p. 342.
*(4) Mr. St. George Mivart, Elementary Anatomy, 1873, p. 396.
The celebrated sculptor, Mr. Woolner, informs me of one little
peculiarity in the external ear, which he has often observed both in
men and women, and of which he perceived the full significance. His
attention was first called to the subject whilst at work on his figure
of Puck, to which he had given pointed ears. He was thus led to
examine the ears of various monkeys, and subsequently more carefully
those of man. The peculiarity consists in a little blunt point,
projecting from the inwardly folded margin, or helix. When present, it
is developed at birth, and according to Prof. Ludwig Meyer, more
frequently in man than in woman. Mr. Woolner made an exact model of
one such case, and sent me the accompanying drawing (see fig. 2).
These points not only project inwards towards the centre of the ear,
but often a little outwards from its plane, so as to be visible when
the head is viewed from directly in front or behind. They are variable
in size, and somewhat in position, standing either a little higher
or lower; and they sometimes occur on one ear and not on the other.
They are not confined to mankind, for I observed a case in one of
the spider-monkeys (Ateles beelzebuth) in our Zoological Gardens;
and Mr. E. Ray Lankester informs me of another case in a chimpanzee in
the gardens at Hamburg. The helix obviously consists of the extreme
margin of the ear folded inwards; and this folding appears to be in
some manner connected with the whole external ear being permanently
pressed backwards. In many monkeys, which do not stand high in the
order, as baboons and some species of Macacus,* the upper portion of
the ear is slightly pointed, and the margin is not at all folded
inwards; but if the margin were to be thus folded, a slight point
would necessarily project inwards towards the centre, and probably a
little outwards from the plane of the ear; and this I believe to be
their origin in many cases. On the other hand, Prof. L. Meyer, in an
able paper recently published,*(2) maintains that the whole case is
one of mere variability; and that the projections are not real ones,
but are due to the internal cartilage on each side of the points not
having been fully developed. I am quite ready to admit that this is
the correct explanation in many instances, as in those figured by
Prof. Meyer, in which there are several minute points, or the whole
margin is sinuous. I have myself seen, through the kindness of Dr.
L. Down, the ear of a microcephalus idiot, on which there is a
projection on the outside of the helix, and not on the inward folded
edge, so that this point can have no relation to a former apex of
the ear. Nevertheless in some cases, my original view, that the points
are vestiges of the tips of formerly erect and pointed ears, still
seems to me probable. I think so from the frequency of their
occurrence, and from the general correspondence in position with
that of the tip of a pointed ear. In one case, of which a photograph
has been sent me, the projection is so large, that supposing, in
accordance with Prof. Meyer's view, the ear to be made perfect by
the equal development of the cartilage throughout the whole extent
of the margin, it would have covered fully one-third of the whole ear.
Two cases have been communicated to me, one in North America, and
the other in England, in which the upper margin is not at all folded
inwards, but is pointed, so that it closely resembles the pointed
ear of an ordinary quadruped in outline. In one of these cases,
which was that of a young child, the father compared the ear with
the drawing which I have given*(3) of the ear of a monkey, the
Cynopithecus niger, and says that their outlines are closely
similar. If, in these two cases, the margin had been folded inwards in
the normal manner, an inward projection must have been formed. I may
add that in two other cases the outline still remains somewhat
pointed, although the margin of the upper part of the ear is
normally folded inwards- in one of them, however, very narrowly. The
following woodcut (see fig. 3) is an accurate copy of a photograph
of the foetus of an orang (kindly sent me by Dr. Nitsche), in which it
may be seen how different the pointed outline of the ear is at this
period from its adult condition, when it bears a close general
resemblance to that of man. It is evident that the folding over of the
tip of such an ear, unless it chang greatly during its further
development, would give rise to a point projecting inwards. On the
whole, it still seems to me probable that the points in question are
in some cases, both in man and apes, vestiges of a former condition.
* See also some remarks, and the drawings of the ears of the
Lemuroidea, in Messrs. Murie and Mivart's excellent paper in
Transactions of the Zoological Society, vol. vii., 1869, pp. 6 and 90.
*(2) Uber das Darwin'sche Spitzohr," Archiv fur Path. Anst. und
Phys., 1871, p. 485.
*(3) The Expression of the Emotions, p. 136.
The nictitating membrane, or third eyelid, with its accessory
muscles and other structures, is especially well developed in birds,
and is of much functional importance to them, as it can be rapidly
drawn across the whole eyeball. It is found in some reptiles and
amphibians, and in certain fishes, as in sharks. It is fairly well
developed in the two lower divisions of the mammalian series,
namely, in the Monotremata and marsupials, and in some few of the
higher mammals, as in the walrus. But in man, the Quadrumana, and most
other mammals, it exists, as is admitted by all anatomists, as a
mere rudiment, called the semilunar fold.*
* Muller's Elements of Physiology, Eng. translat., 1842, vol. ii.,
p. 1117. Owen, Anatomy of Vertebrates, vol. iii., p. 260; ibid., on
the walrus, Proceedings of the Zoological Society, November 8, 1854.
See also R. Knox, Great Artists and Anatomists, p. 106. This
rudiment apparently is somewhat larger in Negroes and Australians than
in Europeans, see Carl Vogt, Lectures on Man, Eng. translat., p. 129.
The sense of smell is of the highest importance to the greater
number of mammals- to some, as the ruminants, in warning them of
danger; to others, as the Carnivora, in finding their prey; to others,
again, as the wild boar, for both purposes combined. But the sense
of smell is of extremely slight service, if any, even to the dark
coloured races of men, in whom it is much more highly developed than
in the white and civilised races.* Nevertheless it does not warn
them of danger, nor guide them to their food; nor does it prevent
the Esquimaux from sleeping in the most fetid atmosphere, nor many
savages from eating half-putrid meat. In Europeans the power differs
greatly in different individuals, as I am assured by an eminent
naturalist who possesses this sense highly developed, and who has
attended to the subject. Those who believe in the principle of gradual
evolution, will not readily admit that the sense of smell in its
present state was originally acquired by man, as he now exists. He
inherits the power in an enfeebled and so far rudimentary condition,
from some early progenitor, to whom it was highly serviceable, and
by whom it was continually used. In those animals which have this
sense highly developed, such as dogs and horses, the recollection of
persons and of places is strongly associated with their odour; and
we can thus perhaps understand how it is, as Dr. Maudsley has truly
remarked,*(2) that the sense of smell in man "is singularly
effective in recalling vividly the ideas and images of forgotten
scenes and places."
* The account given by Humboldt of the power of smell possessed by
the natives of South America is well known, and has been confirmed
by others. M. Houzeau (Etudes sur les Facultes Mentales, &c., tom. i.,
1872, p. 91) asserts that he repeatedly made experiments, and proved
that Negroes and Indians could recognise persons in the dark by
their odour. Dr. W. Ogle has made some curious observations on the
connection between the power of smell and the colouring matter of
the mucous membrane of the olfactory region as well as of the skin
of the body. I have, therefore, spoken in the text of the
dark-coloured races having a finer sense of smell than the white
races. See his paper, Medico-Chirurgical Transactions, London, vol.
liii., 1870, p. 276.
*(2) The Physiology and Pathology of Mind, 2nd ed., 1868, p. 134.
Man differs conspicuously from all the other primates in being
almost naked. But a few short straggling hairs are found over the
greater part of the body in the man, and fine down on that of a woman.
The different races differ much in hairiness; and in the individuals
of the same race the hairs are highly variable, not only in abundance,
but likewise in position: thus in some Europeans the shoulders are
quite naked, whilst in others they bear thick tufts of hair.* There
can be little doubt that the hairs thus scattered over the body are
the rudiments of the uniform hairy coat of the lower animals. This
view is rendered all the more probable, as it is known that fine,
short, and pale-coloured hairs on the limbs and other parts of the
body, occasionally become developed into "thickset, long, and rather
coarse dark hairs," when abnormally nourished near old-standing
inflamed surfaces.*(2)
* Eschricht, "Uber die Richtung der Haare am menschlichen Korper,"
Muller's Archiv fur Anat. und Phys., 1837, s. 47. I shall often have
to refer to this very curious paper.
*(2) Paget, Lectures on Surgical Pathology, 1853, vol. i., p. 71.
I am informed by Sir James Paget that often several members of a
family have a few hairs in their eyebrows much longer than the others;
so that even this slight peculiarity seems to be inherited. These
hairs, too, seem to have their representatives; for in the chimpanzee,
and in certain species of Maeacus, there are scattered hairs of
considerable length rising from the naked skin above the eyes, and
corresponding to our eyebrows; similar long hairs project from the
hairy covering of the superciliary ridges in some baboons.
The fine wool-like hair, or so-called lanugo, with which the human
foetus during the sixth month is thickly covered, offers a more
curious case. It is first developed, during the fifth month, on the
eyebrows and face, and especially round the mouth, where it is much
longer than that on the head. A moustache of this kind was observed by
Eschricht* on a female foetus; but this is not so surprising a
circumstance as it may at first appear, for the two sexes generally
resemble each other in all external characters during an early
period of growth. The direction and arrangement of the hairs on all
parts of the foetal body are the same as in the adult, but are subject
to much variability. The whole surface, including even the forehead
and ears, is thus thickly clothed; but it is a significant fact that
the palms of the hands and the soles of the feet are quite naked, like
the inferior surfaces of all four extremities in most of the lower
animals. As this can hardly be an accidental coincidence, the woolly
covering of the foetus probably represents the first permanent coat of
hair in those mammals which are born hairy. Three or four cases have
been recorded of persons born with their whole bodies and faces
thickly covered with fine long hairs; and this strange condition is
strongly inherited, and is correlated with an abnormal condition of
the teeth.*(2) Prof. Alex. Brandt informs me that he has compared
the hair from the face of a man thus characterised, aged
thirty-five, with the lanugo of a foetus, and finds it quite similar
in texture; therefore, as he remarks, the case may be attributed to an
arrest of development in the hair, together with its continued growth.
Many delicate children, as I have been assured by a surgeon to a
hospital for children, have their backs covered by rather long silky
hairs; and such cases probably come under the same head.
* Eschricht, ibid., ss. 40, 47.
*(2) See my Variation of Animals and Plants under Domestication,
vol. ii., p. 327. Prof. Alex. Brandt has recently sent me an
additional case of a father and son, born in Russia, with these
peculiarities. I have received drawings of both from Paris.
It appears as if the posterior molar or wisdom-teeth were tending to
become rudimentary in the more civilised races of man. These teeth are
rather smaller than the other molars, as is likewise the case with the
corresponding teeth in the chimpanzee and orang; and they have only
two separate fangs. They do not cut through the gums till about the
seventeenth year, and I have been assured that they are much more
liable to decay, and are earlier lost than the other teeth; but this
is denied by some eminent dentists. They are also much more liable
to vary, both in structure and in the period of their development,
than the other teeth.* In the Melanian races, on the other hand, the
wisdom-teeth are usually furnished with three separate fangs, and
are generally sound; they also differ from the other molars in size,
less than in the Caucasian races.*(2) Prof. Schaaffhausen accounts for
this difference between the races by "the posterior dental portion
of the jaw being always shortened" in those that are civilised,*(3)
and this shortening may, I presume, be attributed to civilised men
habitually feeding on soft, cooked food, and thus using their jaws
less. I am informed by Mr. Brace that it is becoming quite a common
practice in the United States to remove some of the molar teeth of
children, as the jaw does not grow large enough for the perfect
development of the normal number.*(4)
* Dr. Webb, "Teeth in Man and the Anthropoid Apes," as quoted by Dr.
C. Carter Blake in Anthropological Review, July, 1867, p. 299.
*(2) Owen, Anatomy of Vertebrates, vol. iii., pp. 320, 321, and 325.
*(3) "On the Primitive Form of the Skull," Eng. translat., in
Anthropological Review, Oct., 1868, p. 426.
*(4) Prof. Montegazza writes to me from Florence, that he has lately
been studying the last molar teeth in the different races of man,
and has come to the same conclusion as that given in my text, viz.,
that in the higher or civilised races they are on the road towards
atrophy or elimination.
With respect to the alimentary canal, I have met with an account
of only a single rudiment, namely the vermiform appendage of the
caecum. The caecum is a branch or diverticulum of the intestine,
ending in a cul-de-sac, and is extremely long in many of the lower
vegetable-feeding mammals. In the marsupial koala it is actually
more than thrice as long as the whole body.* It is sometimes
produced into a long gradually-tapering point, and is sometimes
constricted in parts. It appears as if, in consequence of changed diet
or habits, the caecum had become much shortened in various animals,
the vermiform appendage being left as a rudiment of the shortened
part. That this appendage is a rudiment, we may infer from its small
size, and from the evidence which Prof. Canestrini*(2) has collected
of its variability in man. It is occasionally quite absent, or again
is largely developed. The passage is sometimes completely closed for
half or two-thirds of its length, with the terminal part consisting of
a flattened solid expansion. In the orang this appendage is long and
convoluted: in man it arises from the end of the short caecum, and
is commonly from four to five inches in length, being only about the
third of an inch in diameter. Not only is it useless, but it is
sometimes the cause of death, of which fact I have lately heard two
instances: this is due to small hard bodies, such as seeds, entering
the passage, and causing inflammation.*(3)
* Owen, Anatomy of Vertebrates, vol. iii., pp 416, 434, 441.
*(2) Annuario della Soc. d. Nat. Modena, 1867, p. 94.
*(3) M. C. Martins ("De l'Unite Organique," in Revue des Deux
Mondes, June 15, 1862, p. 16) and Haeckel (Generelle Morphologie, B.
ii., s. 278), have both remarked on the singular fact of this rudiment
sometimes causing death.
In some of the lower Quadrumana, in the Lemuridae and Carnivora,
as well as in many marsupials, there is a passage near the lower end
of the humerus, called the supra-condyloid foramen, through which
the great nerve of the fore limb and often the great artery pass.
Now in the humerus of man, there is generally a trace of this passage,
which is sometimes fairly well developed, being formed by a
depending hook-like process of bone, completed by a band of
ligament. Dr. Struthers,* who has closely attended to the subject, has
now shewn that this peculiarity is sometimes inherited, as it has
occurred in a father, and in no less than four out of his seven
children. When present, the great nerve invariably passes through
it; and this clearly indicates that it is the homologue and rudiment
of the supra-condyloid foramen of the lower animals. Prof. Turner
estimates, as he informs me, that it occurs in about one per cent of
recent skeletons. But if the occasional development of this
structure in man is, as seems probable, due to reversion, it is a
return to a very ancient state of things, because in the higher
Quadrumana it is absent.
* With respect to inheritance, see Dr. Struthers in the Lancet, Feb.
15, 1873, and another important paper, ibid., Jan. 24, 1863, p. 83.
Dr. Knox, as I am informed, was the first anatomist who drew attention
to this peculiar structure in man; see his Great Artists and
Anatomists, p. 63. See also an important memoir on this process by Dr.
Gruber, in the Bulletin de l'Acad. Imp. de St. Petersbourg, tom. xii.,
1867, p. 448.
There is another foramen or perforation in the humerus, occasionally
present in man, which may be called the inter-condyloid. This
occurs, but not constantly, in various anthropoid and other apes,* and
likewise in many of the lower animals. It is remarkable that this
perforation seems to have been present in man much more frequently
during ancient times than recently. Mr. Busk*(2) has collected the
following evidence on this head: Prof. Broca "noticed the
perforation in four and a half per cent of the arm-bones collected
in the 'Cimetiere, du Sud,' at Paris; and in the Grotto of Orrony, the
contents of which are referred to the Bronze period, as many as
eight humeri out of thirty-two were perforated; but this extraordinary
proportion, he thinks, might be due to the cavern having been a sort
of 'family vault.' Again, M. Dupont found thirty per cent of
perforated bones in the caves of the Valley of the Lesse, belonging to
the Reindeer period; whilst M. Leguay, in a sort of dolmen at
Argenteuil, observed twenty-five per cent to be perforated; and M.
Pruner-Bey found twenty-six per cent in the same condition in bones
from Vaureal. Nor should it be left unnoticed that M. Pruner-Bey
states that this condition is common in Guanche skeletons." It is an
interesting fact that ancient races, in this and several other
cases, more frequently present structures which resemble those of
the lower animals than do the modern. One chief cause seems to be that
the ancient races stand somewhat nearer in the long line of descent to
their remote animal-like progenitors.
* Mr. St. George Mivart, Transactions Phil. Soc., 1867, p. 310.
*(2) "On the Caves of Gibraltar," Transactions of the
International Congress of Prehistoric Archaeology, Third Session,
1869, p. 159. Prof. Wyman has lately shewn (Fourth Annual Report,
Peabody Museum, 1871, p. 20), that this perforation is present in
thirty-one per cent of some human remains from ancient mounds in the
Western United States, and in Florida. It frequently occurs in the
negro.
In man, the os coccyx, together with certain other vertebrae
hereafter to be described, though functionless as a tail, plainly
represent this part in other vertebrate animals. At an early embryonic
period it is free, and projects beyond the lower extremities; as may
be seen in the drawing (see fig. 1) of a human embryo. Even after
birth it has been known, in certain rare and anomalous cases,* to form
a small external rudiment of a tail. The os coccyx is short, usually
including only four vertebrae, all anchylosed together: and these
are in a rudimentary condition, for they consist, with the exception
of the basal one, of the centrum alone.*(2) They are furnished with
some small muscles; one of which, as I am informed by Prof. Turner,
has been expressly described by Theile as a rudimentary repetition
of the extensor of the tail, a muscle which is so largely developed in
many mammals.
* Quatrefages has lately collected the evidence on this subject.
Revue des Cours Scientifiques, 1867-1868, p. 625. In 1840
Fleischmann exhibited a human foetus bearing a free tail, which, as is
not always the case, included vertebral bodies; and this tail was
critically examined by the many anatomists present at the meeting of
naturalists at Erlangen (see Marshall in Niederland. Archiv fur
Zoologie, December, 1871).
*(2) Owen, On the Nature of Limbs, 1849, p. 114.
The spinal cord in man extends only as far downwards as the last
dorsal or first lumbar vertebra; but a thread-like structure (the
filum terminale) runs down the axis of the sacral part of the spinal
canal, and even along the back of the coccygeal bones. The upper
part of this filament, as Prof. Turner informs me, is undoubtedly
homologous with the spinal cord; but the lower part apparently
consists merely of the pia mater, or vascular investing membrane. Even
in this case the os coccyx may be said to possess a vestige of so
important a structure as the spinal cord, though no longer enclosed
within a bony canal. The following fact, for which I am also
indebted to Prof. Turner, shews how closely the os coccyx
corresponds with the true tail in the lower animals: Luschka has
recently discovered at the extremity of the coccygeal bones a very
peculiar convoluted body, which is continuous with the middle sacral
artery; and this discovery led Krause and Meyer to examine the tail of
a monkey (Maeacus), and of a cat, in both of which they found a
similarly convoluted body, though not at the extremity.
The reproductive system offers various rudimentary structures; but
these differ in one important respect from the foregoing cases. Here
we are not concerned with the vestige of a part which does not
belong to the species in an efficient state, but with a part efficient
in the one sex, and represented in the other by a mere rudiment.
Nevertheless, the occurrence of such rudiments is as difficult to
explain, on the belief of the separate creation of each species, as in
the foregoing cases. Hereafter I shall have to recur to these
rudiments, and shall shew that their presence generally depends merely
on inheritance, that is, on parts acquired by one sex having been
partially transmitted to the other. I will in this place only give
some instances of such rudiments. It is well known that in the males
of all mammals, including man, rudimentary mammae exist. These in
several instances have become well developed, and have yielded a
copious supply of milk. Their essential identity in the two sexes is
likewise shewn by their occasional sympathetic enlargement in both
during an attack of the measles. The vesicula prostatica, which has
been observed in many male mammals, is now universally acknowledged to
be the homologue of the female uterus, together with the connected
passage. It is impossible to read Leuckart's able description of
this organ, and his reasoning, without admitting the justness of his
conclusion. This is especially clear in the case of those mammals in
which the true female uterus bifurcates, for in the males of these the
vesicula likewise bifurcates.* Some other rudimentary structures
belonging to the reproductive system might have been here adduced.*(2)
* Leuckart, in Todd's Cyclopaedia of Anatomy, 1849-52, vol. iv.,
p. 1415. In man this organ is only from three to six lines in
length, but, like so many other rudimentary parts, it is variable in
development as well as in other characters.
*(2) See, on this subject, Owen, Anatomy of Vertebrates, vol.
iii., pp. 675, 676, 706.
The bearing of the three great classes of facts now given is
unmistakeable. But it would be superfluous fully to recapitulate the
line of argument given in detail in my Origin of Species. The
homological construction of the whole frame in the members of the same
class is intelligible, if we admit their descent from a common
progenitor, together with their subsequent adaptation to diversified
conditions. On any other view, the similarity of pattern between the
hand of a man or monkey, the foot of a horse, the flipper of a seal,
the wing of a bat, &c., is utterly inexplicable.* It is no
scientific explanation to assert that they have all been formed on the
same ideal plan. With respect to development, we can clearly
understand, on the principle of variation supervening at a rather late
embryonic period, and being inherited at a corresponding period, how
it is that the embryos of wonderfully different forms should still
retain, more or less perfectly, the structure of their common
progenitor. No other explanation has ever been given of the marvellous
fact that the embryos of a man, dog, seal, bat, reptile, &c., can at
first hardly be distinguished from each other. In order to
understand the existence of rudimentary organs, we have only to
suppose that a former progenitor possessed the parts in question in
a perfect state, and that under changed habits of life they became
greatly reduced, either from simple disuse, or through the natural
selection of those individuals which were least encumbered with a
superfluous part, aided by the other means previously indicated.
* Prof. Bianconi, in a recently published work, illustrated by
admirable engravings (La Theorie Darwinienne et la creation dite
independante, 1874), endeavours to show that homological structures,
in the above and other cases, can be fully explained on mechanical
principles, in accordance with their uses. No one has shewn so well,
how admirably such structures are adapted for their final purpose; and
this adaptation can, as I believe, be explained through natural
selection. In considering the wing of a bat, he brings forward (p.
218) what appears to me (to use Auguste Comte's words) a mere
metaphysical principle, namely, the preservation "in its integrity
of the mammalian nature of the animal." In only a few cases does he
discuss rudiments, and then only those parts which are partially
rudimentary, such as the little hoofs of the pig and ox, which do
not touch the ground; these he shows clearly to be of service to the
animal. It is unfortunate that he did not consider such cases as the
minute teeth, which never cut through the jaw in the ox, or the mammae
of male quadrupeds, or the wings of certain beetles, existing under
the soldered wing-covers, or the vestiges of the pistil and stamens in
various flowers, and many other such cases. Although I greatly
admire Prof. Bianconi's work, yet the belief now held by most
naturalists seems to me left unshaken, that homological structures are
inexplicable on the principle of mere adaptation.
Thus we can understand how it has come to pass that man and all
other vertebrate animals have been constructed on the same general
model, why they pass through the same early stages of development, and
why they retain certain rudiments in common. Consequently we ought
frankly to admit their community of descent: to take any other view,
is to admit that our own structure, and that of all the animals around
us, is a mere snare laid to entrap our judgment. This conclusion is
greatly strengthened, if we look to the members of the whole animal
series, and consider the evidence derived from their affinities or
classification, their geographical distribution and geological
succession. It is only our natural prejudice, and that arrogance which
made our forefathers declare that they were descended from demigods,
which leads us to demur to this conclusion. But the time will before
long come, when it will be thought wonderful that naturalists, who
were well acquainted with the comparative structure and development of
man, and other mammals, should have believed that each was the work of
a separate act of creation.
CHAPTER II.
ON THE MANNER OF DEVELOPMENT OF MAN FROM SOME LOWER FORM.
IT is manifest that man is now subject to much variability. No two
individuals of the same race are quite alike. We may compare
millions of faces, and each will be distinct. There is an equally
great amount of diversity in the proportions and dimensions of the
various parts of the body; the length of the legs being one of the
most variable points.* Although in some quarters of the world an
elongated skull, and in other quarters a short skull prevails, yet
there is great diversity of shape even within the limits of the same
race, as with the aborigines of America and South Australia- the
latter a race "probably as pure and homogeneous in blood, customs, and
language as any in existence"- and even with the inhabitants of so
confined an area as the Sandwich Islands.*(2) An eminent dentist
assures me that there is nearly as much diversity in the teeth as in
the features. The chief arteries so frequently run in abnormal
courses, that is has been found useful for surgical purposes to
calculate from 1040 corpses how often each course prevails.*(3) The
muscles are eminently variable: thus those of the foot were found by
Prof. Turner*(4) not to be strictly alike in any two out of fifty
bodies; and in some the deviations were considerable. He adds, that
the power of performing the appropriate movements must have been
modified in accordance with the several deviations. Mr. J. Wood has
recorded*(5) the occurrence of 295 muscular variations in thirty-six
subjects, and in another set of the same number no less than 558
variations, those occurring on both sides of the body being only
reckoned as one. In the last set, not one body out of the thirty-six
was "found totally wanting in departures from the standard
descriptions of the muscular system given in anatomical text books." A
single body presented the extraordinary number of twenty-five distinct
abnormalities. The same muscle sometimes varies in many ways: thus
Prof. Macalister describes*(6) no less than twenty distinct variations
in the palmaris accessorius.
* Investigations in the Military and Anthropological Statistics of
American Soldiers, by B. A. Gould, 1869, p. 256.
*(2) With respect to the " Cranial forms of the American
aborigines," see Dr. Aitken Meigs in Proc. Acad. Nat. Sci.
Philadelphia, May, 1868. On the Australians, see Huxley, in Lyell's
Antiquity of Man, 1863, p. 87. On the Sandwich Islanders, Prof. J.
Wyman, Observations on Crania, Boston, 1868, p. 18.
*(3) Anatomy of the Arteries, by R. Quain. Preface, vol. i., 1844.
*(4) Transactions of the Royal Society of Edinburgh, vol. xxiv., pp.
175, 189.
*(5) Proceedings Royal Society, 1867, p. 544; also 1868, pp. 483,
524. There is a previous paper, 1866, p. 229.
*(6) Proc. R. Irish Academy, vol. x., 1868, p. 141.
The famous old anatomist, Wolff,* insists that the internal
viscera are more variable than the external parts: Nulla particula est
quae non aliter et aliter in aliis se habeat hominibus. He has even
written a treatise on the choice of typical examples of the viscera
for representation. A discussion on the beau-ideal of the liver,
lungs, kidneys, &c., as of the human face divine, sounds strange in
our ears.
* Act. Acad. St. Petersburg, 1778, part ii., p. 217.
The variability or diversity of the mental faculties in men of the
same race, not to mention the greater differences between the men of
distinct races, is so notorious that not a word need here be said.
So it is with the lower animals. All who have had charge of menageries
admit this fact, and we see it plainly in our dogs and other
domestic animals. Brehm especially insists that each individual monkey
of those which he kept tame in Africa had its own peculiar disposition
and temper: he mentions one baboon remarkable for its high
intelligence; and the keepers in the Zoological Gardens pointed out to
me a monkey, belonging to the New World division, equally remarkable
for intelligence. Rengger, also, insists on the diversity in the
various mental characters of the monkeys of the same species which
he kept in Paraguay; and this diversity, as he adds, is partly innate,
and partly the result of the manner in which they have been treated or
educated.*
* Brehm, Illustriertes Thierleben, B. i., ss. 58, 87. Rengger,
Saugethiere von Paraguay, s. 57.
I have elsewhere* so fully discussed the subject of Inheritance,
that I need here add hardly anything. A greater number of facts have
been collected with respect to the transmission of the most
trifling, as well as of the most important characters in man, than
in any of the lower animals; though the facts are copious enough
with respect to the latter. So in regard to mental qualities, their
transmission is manifest in our dogs, horses, and other domestic
animals. Besides special tastes and habits, general intelligence,
courage, bad and good temper, &c., are certainly transmitted. With man
we see similar facts in almost every family; and we now know,
through the admirable labours of Mr. Galton,*(2) that genius which
implies a wonderfully complex combination of high faculties, tends
to be inherited; and, on the other hand, it is too certain that
insanity and deteriorated mental powers likewise run in families.
* Variation of Animals and Plants under Domestication, vol. ii.,
chap. xii.
*(2) Hereditary Genius: an Inquiry into its Laws and Consequences,
1869.
With respect to the causes of variability, we are in all cases
very ignorant; but we can see that in man as in the lower animals,
they stand in some relation to the conditions to which each species
has been exposed, during several generations. Domesticated animals
vary more than those in a state of nature; and this is apparently
due to the diversified and changing nature of the conditions to
which they have been subjected. In this respect the different races of
man resemble domesticated animals, and so do the individuals of the
same race, when inhabiting. a very wide area, like that of America. We
see the influence of diversified conditions in the more civilised
nations; for the members belonging to different grades of rank, and
following different occupations, present a greater range of
character than do the members of barbarous nations. But the uniformity
of savages has often been exaggerated, and in some cases can hardly be
said to exist.* It is, nevertheless, an error to speak of man, even if
we look only to the conditions to which he has been exposed, as "far
more domesticated"*(2) than any other animal. Some savage races,
such as the Australians, are not exposed to more diversified
conditions than are many species which have a wide range. In another
and much more important respect, man differs widely from any
strictly domesticated animal; for his breeding has never long been
controlled, either by methodical or unconscious selection. No race
or body of men has been so completely subjugated by other men, as that
certain individuals should be preserved, and thus unconsciously
selected, from somehow excelling in utility to their masters. Nor have
certain male and female individuals been intentionally picked out
and matched, except in the well-known case of the Prussian grenadiers;
and in this case man obeyed, as might have been expected, the law of
methodical selection; for it is asserted that many tall men were
reared in the villages inhabited by the grenadiers and their tall
wives. In Sparta, also, a form of selection was followed, for it was
enacted that all children should be examined shortly after birth;
the well-formed and vigorous being preserved, the others left to
perish.*(3)
* Mr. Bates remarks (The Naturalist on the Amazons, 1863, vol. ii p.
159), with respect to the Indians of the same South American tribe,
"no two of them were at all similar in the shape of the head; one
man had an oval visage with fine features, and another was quite
Mongolian in breadth and prominence of cheek, spread of nostrils,
and obliquity of eyes."
*(2) Blumenbach, Treatises on Anthropology., Eng. translat., 1865,
p. 205.
*(3) Mitford's History of Greece, vol. i., p. 282. It appears from a
passage in Xenophon's Memorabilia, B. ii. 4 (to which my attention has
been called by the Rev. J. N. Hoare), that it was a well recognised
principle with the Greeks, that men ought to select their wives with a
view to the health and vigour of their children. The Grecian poet,
Theognis, who lived 550 B. C., clearly saw how important selection, if
carefully applied, would be for the improvement of mankind. He saw,
likewise, that wealth often checks the proper action of sexual
selection. He thus writes:
With kine and horses, Kurnus! we proceed
By reasonable rules, and choose a breed
For profit and increase at any price:
Of a sound stock, without defect or vice.
But, in the daily matches that we make,
The price is everything: for money's sake,
Men marry: women are in marriage given
The churl or ruffian, that in wealth has thriven,
May match his offspring with the proudest race:
Thus everything is mix'd, noble and base!
If then in outward manner, form, and mind,
You find us a degraded, motley kind,
Wonder no more, my friend! the cause is plain,
And to lament the consequence is vain.
(The Works of J. Hookham Frere, vol. ii., 1872, p. 334.)
If we consider all the races of man as forming a single species, his
range is enormous; but some separate races, as the Americans and
Polynesians, have very wide ranges. It is a well-known law that
widely-ranging species are much more variable than species with
restricted ranges; and the variability of man may with more truth be
compared with that of widely-ranging species, than with that of
domesticated animals.
Not only does variability appear to be induced in man and the
lower animals by the same general causes, but in both the same parts
of the body are effected in a closely analogous manner. This has
been proved in such full detail by Godron and Quatrefages, that I need
here only refer to their works.* Monstrosities, which graduate into
slight variations, are likewise so similar in man and the lower
animals, that the same classification and the same terms can be used
for both, as has been shewn by Isidore Geoffroy St-Hilaire.*(2) In
my work on the variation of domestic animals, I have attempted to
arrange in a rude fashion the laws of variation under the following
heads:- The direct and definite action of changed conditions, as
exhibited by all or nearly all the individuals of the same species,
varying in the same manner under the same circumstances. The effects
of the long-continued use or disuse of parts. The cohesion of
homologous parts. The variability of multiple parts. Compensation of
growth; but of this law I have found no good instance in the case of
man. The effects of the mechanical pressure of one part on another; as
of the pelvis on the cranium of the infant in the womb. Arrests of
development, leading to the diminution or suppression of parts. The
reappearance of long-lost characters through reversion. And lastly,
correlated variation. All these so-called laws apply equally to man
and the lower animals; and most of them even to plants. It would be
superfluous here to discuss all of them;*(3) but several are so
important, that they must be treated at considerable length.
* Godron, De l'Espece, 1859, tom. ii., livre 3. Quatrefages, Unite
de l'Espece Humaine, 1861. Also Lectures on Anthropology, given in the
Revue des Cours Scientifiques, 1866-1868.
*(2) Hist. Gen. et Part. des Anomalies de l'Organisation, tom. i.,
1832.
*(3) I have fully discussed these laws in my Variation of Animals
and Plants under Domestication, vol. ii., chaps. xxii. and xxiii. M.
J. P. Durand has lately (1868) published a valuable essay, De
l'Influence des Milieux, &c. He lays much stress, in the case of
plants, on the nature of the soil.
The Direct and Definite Action of Changed Conditions.- This is a
most perplexing subject. It cannot be denied that changed conditions
produce some, and occasionally a considerable effect, on organisms
of all kinds; and it seems at first probable that if sufficient time
were allowed this would be the invariable result. But I have failed to
obtain clear evidence in favour of this conclusion; and valid
reasons may be urged on the other side, at least as far as the
innumerable structures are concerned, which are adapted for special
ends. There can, however, be no doubt that changed conditions induce
an almost indefinite amount of fluctuating variability, by which the
whole organisation is rendered in some degree plastic.
In the United States, above 1,000,000 soldiers, who served in the
late war, were measured, and the States in which they were born and
reared were recorded.* From this astonishing number of observations it
is proved that local influences of some kind act directly on
stature; and we further learn that "the State where the physical
growth has in great measure taken place, and the State of birth, which
indicates the ancestry, seem to exert a marked influence on the
stature." For instance, it is established, "that residence in the
Western States, during the years of growth, tends to produce
increase of stature." On the other hand, it is certain that with
sailors, their life delays growth, as shewn "by the great difference
between the statures of soldiers and sailors at the ages of
seventeen and eighteen years." Mr. B. A. Gould endeavoured to
ascertain the nature of the influences which thus act on stature;
but he arrived only at negative results, namely that they did not
relate to climate, the elevation of the land, soil, nor even "in any
controlling degree" to the abundance or the need of the comforts of
life. This latter conclusion is directly opposed to that arrived at
by, Villerme, from the statisties of the height of the conscripts in
different parts of France. When we compare the differences in
stature between the Polynesian chiefs and the lower orders within
the same islands, or between the inhabitants of the fertile volcanic
and low barren coral islands of the same ocean,*(2) or again between
the Fuegians on the eastern and western shores of their country, where
the means of subsistence are very different, it is scarcely possible
to avoid the conclusion that better food and greater comfort do
influence stature. But the preceding statements shew how difficult
it is to arrive at any precise result. Dr. Beddoe has lately proved
that, with the inhabitants of Britain, residence in towns and
certain occupations have a deteriorating influence on height; and he
infers that the result is to a certain extent inherited, as is
likewise the case in the United States. Dr. Beddoe further believes
that wherever a "race attains its maximum of physical development,
it rises highest in energy and moral vigour."*(3)
* Investigations in Military and Anthrop. Statistics, &c., 1869,
by B. A. Gould, pp. 93, 107, 126, 131, 134.
*(2) For the Polynesians, see Prichard's Physical History of
Mankind, vol. v., 1847, pp. 145, 283. Also Godron, De l'Espece, tom.
ii., p. 289. There is also a remarkable difference in appearance
between the closely-allied Hindoos inhabiting the Upper Ganges and
Bengal; see Elphinstone's History of India, vol. i., p. 324.
*(3) Memoirs, Anthropological Society, vol. iii., 1867-69, pp.
561, 565, 567.
Whether external conditions produce any other direct effect on man is
not known. It might have been expected that differences of climate
would have had a marked influence, inasmuch as the lungs and kidneys
are brought into activity under a low temperature, and the liver and
skin under a high one.* It was formerly thought that the colour of the
skin and the character of the hair were determined by light or heat;
and although it can hardly be denied that some effect is thus
produced, almost all observers now agree that the effect has been very
small, even after exposure during many ages. But this subject will
be more properly discussed when we treat of the different races of
mankind. With our domestic animals there are grounds for believing
that cold and damp directly affect the growth of the hair; but I
have not met with any evidence on this head in the case of man.
* Dr. Brakenridge, "Theory of Diathesis," Medical Times, June 19 and
July 17, 1869.
Effects of the increased Use and Disuse of Parts.- It is well
known that use strengthens the muscles in the individual, and complete
disuse, or the destruction of the proper nerve, weakens them. When the
eye is destroyed, the optic nerve often becomes atrophied. When an
artery is tied, the lateral channels increase not only in diameter,
but in the thickness and strength of their coats. When one kidney
ceases to act from disease, the other increases in size, and does
double work. Bones increase not only in thickness, but in length, from
carrying a greater weight.* Different occupations, habitually
followed, lead to changed proportions in various parts of the body.
Thus it was ascertained by the United States Commission*(2) that the
legs of the sailors employed in the late war were longer by 0.217 of
an inch than those of the soldiers, though the sailors were on an
average shorter men; whilst their arms were shorter by 1.09 of an
inch, and therefore, out of proportion, shorter in relation to their
lesser height. This shortness of the arms is apparently due to their
greater use, and is an unexpected result: but sailors chiefly use
their arms in pulling, and not in supporting weights. With sailors,
the girth of the neck and the depth of the instep are greater,
whilst the circumference of the chest, waist, and hips is less, than
in soldiers.
* I have given authorities for these several statements in my
Variation of Animals and Plants under Domestication, vol. ii., pp.
297-300. Dr. Jaeger, "Uber das Langenwachsthum der Knochen," Jenaische
Zeitschrift, B. v., Heft. i.
*(2) Investigations, &c., by B. A. Gould, 1869, p. 288.
Whether the several foregoing modifications would become hereditary,
if the same habits of life were followed during many generations, is
not known, but it is probable. Rengger* attributes the thin legs and
thick arms of the Payaguas Indians to successive generations having
passed nearly their whole lives in canoes, with their lower
extremities motionless. Other writers have come to a similar
conclusion in analogous cases. According to Cranz,*(2) who lived for a
long time with the Esquimaux, "The natives believe that ingenuity
and dexterity in seal-catching (their highest art and virtue) is
hereditary; there is is really something in it, for the son of a
celebrated seal-catcher will distinguish himself, though he lost his
father in childhood." But in this case it is mental aptitude, quite as
much as bodily structure, which appears to be inherited. It is
asserted that the hands of English labourers are at birth larger
than those of the gentry.*(3) From the correlation which exists, at
least in some cases,*(4) between the development of the extremities
and of the jaws, it is possible that in those classes which do not
labour much with their hands and feet, the jaws would be reduced in
size from this cause. That they are generally smaller in refined and
civilized men than in hard-working men or savages, is certain. But
with savages, as Mr. Herbert Spencer*(5) has remarked, the greater use
of the jaws in chewing coarse, uncooked food, would act in a direct
manner on the masticatory muscles, and on the bones to which they
are attached. In infants, long before birth, the skin on the soles
of the feet is thicker than on any other part of the body;*(6) and
it can hardly be doubted that this is due to the inherited effects
of pressure during a long series of generations.
* Saugethiere von Paraguay, 1830, s. 4.
*(2) History of Greenland, Eng. translat., 1767, vol. i., p. 230
*(3) Intermarriage, by Alex. Walker, 1838, p. 377.
*(4) The Variation of Animals and Plants under Domestication, vol.
i., p. 173.
*(5) Principles of Biology, vol. i., p. 455.
*(6) Paget, Lectures on Surgical Pathology, vol. ii, 1853, p. 209.
It is familiar to every one that watchmakers and engravers are
liable to be short-sighted, whilst men living much out of doors, and
especially savages, are generally long-sighted.* Short-sight and
long-sight certainly tend to be inherited.*(2) The inferiority of
Europeans, in comparison with savages, in eyesight and in the other
senses, is no doubt the accumulated and transmitted effect of lessened
use during many generations; for Rengger*(3) states that he has
repeatedly observed Europeans, who had been brought up and spent their
whole lives with the wild Indians, who nevertheless did not equal them
in the sharpness of their senses. The same naturalist observes that
the cavities in the skull for the reception of the several
sense-organs are larger in the American aborigines than in
Europeans; and this probably indicates a corresponding difference in
the dimensions of the organs themselves. Blumenbach has also
remarked on the large size of the nasal cavities in the skulls of
the American aborigines, and connects this fact with their
remarkably acute power of smell. The Mongolians of the plains of
northern Asia, according to Pallas, have wonderfully perfect senses;
and Prichard believes that the great breadth of their skulls across
the zygomas follows from their highly-developed sense organs.*(4)
* It is a singular and unexpected fact that sailors are inferior
to landsmen in their mean distance of distinct vision. Dr. B. A. Gould
(Sanitary Memoirs of the War of the Rebellion, 1869 p. 530), has
proved this to be the case; and he accounts for it by the ordinary
range of vision in sailors being "restricted to the length of the
vessel and the height of the masts."
*(2) The Variation of Animal and Plants under Domestication, vol.
i., p. 8.
*(3) Saugethiere von Paraguay, s. 8, 10. I have had good
opportunities for observing the extraordinary power of eyesight in the
Fuegians. See also Lawrence (Lectures on Physiology, &c., 1822, p.
404) on this same subject. M. Giraud-Teulon has recently collected
(Revue des Cours Scientifiques, 1870, p. 625) a large and valuable
body of evidence proving that the cause of short-sight, "C'est le
travail assidu, de pres."
*(4) Prichard, Physical History of Mankind, on the authority of
Blumenbach, vol. i., 1841, p. 311; for the statement by Pallas, vol.
iv., 1844, p. 407.
The Quechua Indians inhabit the lofty plateaux of Peru; and Alcide
d'Orbigny states* that, from continually breathing a highly rarefied
atmosphere, they have acquired chests and lungs of extraordinary
dimensions. The cells, also, of the lungs are larger and more numerous
than in Europeans. These observations have been doubted, but Mr. D.
Forbes carefully measured many Aymaras, an allied race, living at
the height of between 10,000 and 15,000 feet; and he informs me*(2)
that they differ conspicuously from the men of all other races seen by
him in the circumference and length of their bodies. In his table of
measurements, the stature of each man is taken at 1000, and the
other measurements are reduced to this standard. It is here seen
that the extended arms of the Aymaras are shorter than those of
Europeans, and much shorter than those of Negroes. The legs are
likewise shorter; and they present this remarkable peculiarity, that
in every Aymara measured, the femur is actually shorter than the
tibia. On an average, the length of the femur to that of the tibia
is as 211 to 252; whilst in two Europeans, measured at the same
time, the femora to the tibiae were as 244 to 230; and in three
Negroes as 258 to 241. The humerus is likewise shorter relatively to
the forearm. This shortening of that part of the limb which is nearest
to the body, appears to be, as suggested to me by Mr. Forbes, a case
of compensation in relation with the greatly increased length of the
trunk. The Aymaras present some other singular points of structure,
for instance, the very small projection of the heel.
* Quoted by Prichard, Researches into the Physical History of
Mankind, vol. v., p. 463.
*(2) Mr. Forbes' valuable paper is now published in the Journal of
the Ethnological Society of London, new series, vol. ii., 1870, p.
193.
These men are so thoroughly acclimatised to their cold and lofty
abode, that when formerly carried down by Spaniards to the low eastern
plains, and when now tempted down by high wages to the
gold-washings, they suffer a frightful rate of mortality. Nevertheless
Mr. Forbes found a few pure families which had survived during two
generations: and he observed that they still inherited their
characteristic peculiarities. But it was manifest, even without
measurement, that these peculiarities had all decreased; and on
measurement, their bodies were found not to be so much elongated as
those of the men on the high plateau; whilst their femora had become
somewhat lengthened, as had their tibiae, although in a less degree.
The actual measurements may be seen by consulting Mr. Forbes's memoir.
From these observations, there can, I think, be no doubt that
residence during many generations at a great elevation tends, both
directly and indirectly, to induce inherited modifications in the
proportions of the body.*
* Dr. Wilckens (Landwirthschaft. Wochenblatt, No. 10, 1869) has
lately published an interesting essay shewing how domestic animals,
which live in mountainous regions, have their frames modified.
Although man may not have been much modified during the latter
stages of his existence through the increased or decreased use of
parts, the facts now given shew that his liability in this respect has
not been lost; and we positively know that the same law holds good
with the lower animals. Consequently we may infer that when at a
remote epoch the progenitors of man were in a transitional state,
and were changing from quadrupeds into bipeds, natural selection would
probably have been greatly aided by the inherited effects of the
increased or diminished use of the different parts of the body.
Arrests of Development.- There is a difference between arrested
development and arrested growth, for parts in the former state
continue to grow whilst still retaining their early condition. Various
monstrosities come under this head; and some, as a cleft palate, are
known to be occasionally inherited. It will suffice for our purpose to
refer to the arrested brain-development of microcephalous idiots, as
described in Vogt's memoir.* Their skulls are smaller, and the
convolutions of the brain are less complex than in normal men. The
frontal sinus, or the projection over the eyebrows, is largely
developed, and the jaws are prognathous to an "effrayant" degree; so
that these idiots somewhat resemble the lower types of mankind.
Their intelligence, and most of their mental faculties, are
extremely feeble. They cannot acquire the power of speech, and are
wholly incapable of prolonged attention, but are much given to
imitation. They are strong and remarkably active, continually
gambolling and jumping about, and making grimaces. They often ascend
stairs on all-fours; and are curiously fond of climbing up furniture
or trees. We are thus reminded of the delight shewn by almost all boys
in climbing trees; and this again reminds us how lambs and kids,
originally alpine animals, delight to frisk on any hillock, however
small. Idiots also resemble the lower animals in some other
respects; thus several cases are recorded of their carefully
smelling every mouthful of food before eating it. One idiot is
described as often using his mouth in aid of his hands, whilst hunting
for lice. They are often filthy in their habits, and have no sense
of decency; and several cases have been published of their bodies
being remarkably hairy.*(2)
* Memoires sur les Microcephales, 1867, pp. 50, 125, 169, 171,
184-198.
*(2) Prof. Laycock sums up the character of brute-like idiots by
calling them theroid; Journal of Mental Science,, July, 1863. Dr.
Scott (The Deaf and Dumb, 2nd ed., 1870, p. 10) has often observed the
imbeciles smelling their food. See, on this same subject, and on the
hairiness of idiots, Dr. Maudsley, Body and Mind, 1870, pp. 46-51.
Pinel has also given a striking case of hairiness in an idiot.
Reversion.- Many of the cases to be here given, might have been
introduced under the last heading. When a structure is arrested in its
development, but still continues growing, until it closely resembles a
corresponding structure in some lower and adult member of the same
group, it may in one sense be considered as a case of reversion. The
lower members in a group give us some idea how the common progenitor
was probably constructed; and it is hardly credible that a complex
part, arrested at an early phase of embryonic development, should go
on growing so as ultimately to perform its proper function, unless
it had acquired such power during some earlier state of existence,
when the present exceptional or arrested structure was normal. The
simple brain of a microcephalous idiot, in as far as it resembles that
of an ape' may in this sense be said to offer a case of reversion.*
There are other cases which come more strictly under our present
head of reversion. Certain structures, regularly occurring in the
lower members of the group to which man belongs, occasionally make
their appearance in him, though not found in the normal human
embryo; or, if normally present in the human embryo, they become
abnormally developed, although in a manner which is normal in the
lower members of the group. These remarks will be rendered clearer
by the following illustrations.
* In my Variation of Animals under Domestication (vol. ii., p.
57), I attributed the not very rare cases of supernumerary mammae in
women to reversion. I was led to this as a probable conclusion, by the
additional mammae being generally placed symmetrically on the
breast; and more especially from one case, in which a single efficient
mamma occurred in the inguinal region of a woman, the daughter of
another woman with supernumerary mammae. But I now find (see, for
instance, Prof. Preyer, Der Kampf um das Dasein, 1869, s. 45) that
mammae erraticae, occur in other situations, as on the back, in the
armpit, and on the thigh; the mammae in this latter instance having
given so much milk that the child was thus nourished. The
probability that the additional mammae are due to reversion is thus
much weakened; nevertheless, it still seems to me probable, because
two pairs are often found symmetrically on the breast; and of this I
myself have received information in several cases. It is well known
that some lemurs normally have two pairs of mammae on the breast. Five
cases have been recorded of the presence of more than a pair of mammee
(of course rudimentary) in the male sex of mankind; see Journal of
Anat. and Physiology, 1872, p. 56, for a case given by Dr. Handyside
in which two brothers exhibited this peculiarity; see also a paper
by Dr. Bartels, in Reichert's and du Bois-Reymond's Archiv., 1872,
p. 304. In one of the cases alluded to by Dr. Bartels, a man bore five
mammae, one being medial and placed above the navel; Meckel von
Hemsbach thinks that this latter case is illustrated by a medial mamma
occurring in certain Cheiroptera. On the whole, we may well doubt if
additional mammae would ever have been developed in both sexes of
mankind, had not his early progenitors been provided with more than
a single pair.
In the above work (vol. ii., p. 12), I also attributed, though
with much hesitation, the frequent cases of polydactylism in men and
various animals to reversion. I was partly led to this through Prof.
Owen's statement, that some of the Ichthyopterygia possesses more than
five digits, and therefore, as I supposed, had retained a primordial
condition; but Prof. Gegenbaur (Jenaische Zeitschrift, B. v., Heft
3, s. 341), disputes Owen's conclusion. On the other hand, according
to the opinion lately advanced by Dr. Gunther, on the paddle of
Ceratodus, which is provided with articulated bony rays on both
sides of a central chain of bones, there seems no great difficulty
in admitting that six or more digits on one side, or on both sides,
might reappear through reversion. I am informed by Dr. Zouteveen
that there is a case on record of a man having twenty-four fingers and
twenty-four toes! I was chiefly led to the conclusion that the
presence of supernumerary digits might be due to reversion from the
fact that such digits, not only are strongly inherited, but, as I then
believed, had the power of regrowth after amputation, like the
normal digits of the lower Vertebrata. But I have explained in the
second edition of my Variation under Domestication why I now place
little reliance on the recorded cases of such regrowth. Nevertheless
it deserves notice, inasmuch as arrested development and reversion are
intimately related processes; that various structures in an
embryonic or arrested condition, such as a cleft palate, bifid uterus,
&c., are frequently accompanied by polydactylism. This has been
strongly insisted on by Meckel and Isidore Geoffroy St-Hilaire. But at
present it is the safest course to give up altogether the idea that
there is any relation between the development of supernumerary
digits and reversion to some lowly organized progenitor of man.
In various mammals the uterus graduates from a double organ with two
distinct orifices and two passages, as in the marsupials, into a
single organ, which is in no way double except from having a slight
internal fold, as in the higher apes and man. The rodents exhibit a
perfect series of gradations between these two extreme states. In
all mammals the uterus is developed from two simple primitive tubes,
the inferior portions of which form the cornua; and it is in the words
of Dr. Farre, "by the coalescence of the two cornua at their lower
extremities that the body of the uterus is formed in man; while in
those animals in which no middle portion or body exists, the cornua
remain ununited. As the development of the uterus proceeds, the two
cornua become gradually shorter, until at length they are lost, or, as
it were, absorbed into the body of the uterus." The angles of the
uterus are still produced into cornua, even in animals as high up in
the scale as the lower apes and lemurs.
Now in women, anomalous cases are not very infrequent, in which
the mature uterus is furnished with cornua, or is partially divided
into two organs; and such cases, according to Owen, repeat "the
grade of concentrative development," attained by certain rodents. Here
perhaps we have an instance of a simple arrest of embryonic
development, with subsequent growth and perfect functional
development; for either side of the partially double uterus is capable
of performing the proper office of gestation. In other and rarer
cases, two distinct uterine cavities are formed, each having its
proper orifice and passage.* No such stage is passed through during
the ordinary development of the embryo; and it is difficult to
believe, though perhaps not impossible, that the two simple, minute,
primitive tubes should know how (if such an expression may be used) to
grow into two distinct uteri, each with a well-constructed orifice,and
passage, and each furnished with numerous muscles, nerves, glands
and vessels, if they had not formerly passed through a similar
course of development, as in the case of existing marsupials. No one
will pretend that so perfect a structure as the abnormal double uterus
in woman could be the result of mere chance. But the principle of
reversion, by which a long-lost structure is called back into
existence, might serve as the guide for its full development, even
after the lapse of an enormous interval of time.
* See Dr. A. Farre's well-known article in the Cyclopaedia of
Anatomy and Physiology, vol. v., 1859, p. 642. Owen, Anatomy of
Vertebrates, vol. iii., 1868, p. 687. Professor Turner, in Edinburgh
Medical Journal, February, 1865.
Professor Canestrini, after discussing the foregoing and various
analogous cases, arrives at the same conclusion as that just given. He
adduces another instance, in the case of the malar bone,* which, in
some of the Quadrumana and other mammals, normally consists of two
portions. This is its condition in the human foetus when two months
old; and through arrested development, it sometimes remains thus in
man when adult, more especially in the lower prognathous races.
Hence Canestrini concludes that some ancient progenitor of man must
have had this bone normally divided into two portions, which
afterwards became fused together. In man the frontal bone consists
of a single piece, but in the embryo, and in children, and in almost
all the lower mammals, it consists of two pieces separated by a
distinct suture. This suture occasionally persists more or less
distinctly in man after maturity; and more frequently in ancient
than in recent crania, especially, as Canestrini has observed, in
those exhumed from the Drift, and belonging to the brachycephalic
type. Here again he comes to the same conclusion as in the analogous
case of the malar bones. In this, and other instances presently to
be given, the cause of ancient races approaching the lower animals
in certain characters more frequently than do the modern races,
appears to be, that the latter stand at a somewhat greater distance in
the long line of descent from their early semi-human progenitors.
* Annuario della Soc. dei Naturalisti, Modena, 1867, p. 83. Prof.
Canestrini gives extracts on this subject from various authorities.
Laurillard remarks, that as he has found a complete similarity in
the form, proportions, and connection of the two malar bones in
several human subjects and in certain apes, he cannot consider this
disposition of the parts as simply accidental. Another paper on this
same anomaly has been published by Dr. Saviotti in the Gazzetta
delle Cliniche, Turin, 1871, where he says that traces of the division
may be detected in about two per cent of adult skulls; he also remarks
that it more frequently occurs in prognathous skulls, not of the Aryan
race, than in others. See also G. Delorenzi on the same subject;
"Tre nuovi casi d'anomalia dell' osso malare," Torino, 1872. Also,
E. Morselli, "Sopra una rara anomalia dell' osso malare," Modena,
1872. Still more recently Gruber has written a pamphlet on the
division of this bone. I give these references because a reviewer,
without any grounds or scruples, has thrown doubts on my statements.
Various other anomalies in man, more or less analogous to the
foregoing, have been advanced by different authors, as cases of
reversion; but these seem not a little doubtful, for we have to
descend extremely low in the mammalian series, before we find such
structures normally present.*
* A whole series of cases is given by Isidore Geoffroy St-Hilaire,
Hist. des Anomalies, tom, iii, p. 437. A reviewer (Journal of
Anatomy and Physiology, 1871, p. 366) blames me much for not having
discussed the numerous cases, which have been recorded, of various
parts arrested in their development. He says that, according to my
theory, "every transient condition of an organ, during its
development, is not only a means to an end, but once was an end in
itself." This does not seem to me necessarily to hold good. Why should
not variations occur during an early period of development, having
no relation to reversion; yet such variations might be preserved and
accumulated, if in any way serviceable, for instance, in shortening
and simplifying the course of development? And again, why should not
injurious abnormalities, such as atrophied or hypertrophied parts,
which have no relation to a former state of existence, occur at an
early period, as well as during maturity?
In man, the canine teeth are perfectly efficient instruments for
mastication. But their true canine character, as Owen* remarks, "is
indicated by the conical form of the crown, which terminates in an
obtuse point, is convex outward and flat or sub-concave within, at the
base of which surface there is a feeble prominence. The conical form
is best expressed in the Melanian races, especially the Australian.
The canine is more deeply implanted, and by a stronger fang than the
incisors." Nevertheless, this tooth no longer serves man as a
special weapon for tearing his enemies or prey; it may, therefore,
as far as its proper function is concerned, be considered as
rudimentary. In every large collection of human skulls some may be
found, as Haeckel*(2) observes, with the canine teeth projecting
considerably beyond the others in the same manner as in the
anthropomorphous apes, but in a less degree. In these cases, open
spaces between the teeth in the one jaw are left for the reception
of the canines of the opposite jaw. An inter-space of this kind in a
Kaffir skull, figured by Wagner, is surprisingly wide.*(3) Considering
how few are the ancient skulls which have been examined, compared to
recent skulls, it is an interesting fact that in at least three
cases the canines project largely; and in the Naulette jaw they are
spoken of as enourmous.*(4)
* Anatomy of Vertebrates, vol. iii., 1868, p. 323.
*(2) Generelle Morphologie, 1866, B. ii., s. clv.
*(3) Carl Vogt's Lectures on Man, Eng. translat., 1864, p. 151.
*(4) C. Carter Blake, on a jaw from La Naulette, Anthropological
Review, 1867, p. 295. Schaaffhausen, ibid., 1868, p. 426.
Of the anthropomorphous apes the males alone have their canines
fully developed; but in the female gorilla, and in a less degree in
the female orang, these teeth project considerably beyond the
others; therefore the fact, of which I have been assured, that women
sometimes have considerably projecting canines, is no serious
objection to the belief that their occasional great development in man
is a case of reversion to an ape-like progenitor. He who rejects
with scorn the belief that the shape of his own canines, and their
occasional great development in other men, are due to our early
forefathers having been provided with these formidable weapons, will
probably reveal, by sneering, the line of his descent. For though he
no longer intends, nor has the power, to use these teeth as weapons,
he will unconsciously retract his "snarling muscles" (thus named by
Sir C. Bell),* so as to expose them ready for action, like a dog
prepared to fight.
* The Anatomy of Expression, 1844, pp. 110, 131.
Many muscles are occasionally developed in man, which are proper
to the Quadrumana or other mammals. Professor Vlacovich* examined
forty male subjects, and found a muscle, called by him the
ischio-pubic, in nineteen of them; in three others there was a
ligament which represented this muscle; and in the remaining
eighteen no trace of it. In only two out of thirty female subjects was
this muscle developed on both sides, but in three others the
rudimentary ligament was present. This muscle, therefore, appears to
be much more common in the male than in the female sex; and on the
belief in the descent of man from some lower form, the fact is
intelligible; for it has been detected in several of the lower
animals, and in all of these it serves exclusively to aid the male
in the act of reproduction.
* Quoted by Prof. Canestrini in the Annuario, della Soc. dei
Naturalisti, 1867, p. 90.
Mr. J. Wood, in his valuable series of papers,* has minutely
described a vast number of muscular variations in man, which
resemble normal structures in the lower animals. The muscles which
closely resemble those regularly present in our nearest allies, the
Quadrumans, are too numerous to be here even specified. In a single
male subject, having a strong bodily frame, and well-formed skull,
no less than seven muscular variations were observed, all of which
plainly represented muscles proper to various kinds of apes. This man,
for instance, had on both sides of his neck a true and powerful
"levator claviculae," such as is found in all kinds of apes, and which
is said to occur in about one out of sixty human subjects.*(2)
Again, this man had "a special abductor of the metatarsal bone of
the fifth digit, such as Professor Huxley and Mr. Flower have shewn to
exist uniformly in the higher and lower apes." I will give only two
additional cases; the acromio-basilar muscle is found in all mammals
below man, and seems to be correlated with a quadrupedal gait,*(3) and
it occurs in about one out of sixty human subjects. In the lower
extremities Mr. Bradley*(4) found an abductor ossis metatarsi quinti
in both feet of man; this muscle had not up to that time been recorded
in mankind, but is always present in the anthropomorphous apes. The
muscles of the hands and arms- parts which are so eminently
characteristic of man- are extremely liable to vary, so as to resemble
the corresponding muscles in the lower animals.*(5) Such
resemblances are either perfect or imperfect; yet in the latter case
they are manifestly of a transitional nature. Certain variations are
more common in man, and others in woman, without our being able to
assign any reason. Mr. Wood, after describing numerous variations,
makes the following pregnant remark. "Notable departures from the
ordinary type of muscular structures run in grooves or directions,
which must be taken to indicate some unknown factor, of much
importance to a comprehensive knowledge of general and scientific
anatomy."*(6)
* These papers deserve careful study by any one who desires to learn
how frequently our muscles vary, and in varying come to resemble those
of the Quadrumana. The following references relate to the few points
touched on in my text: Proc. Royal Soc., vol. xiv., 1865, pp. 379-384;
vol. xv., 1866, pp. 241, 242; vol. xv., 1867, p. 544; vol. xvi., 1868,
p. 524. I may here add that Dr. Murie and Mr. St. George Mivart have
shewn in their Memoir on the Lemuroidea (Transactions, Zoological
Society, vol. vii., 1869, p. 96), how extraordinarily variable some of
the muscles are in these animals, the lowest members of the
primates. Gradations, also, in the muscles leading to structures found
in animals still lower in the scale, are numerous in the Lemuroidea.
*(2) See also Prof. Macalister in Proceedings, Royal Irish
Academy, vol. x., 1868, p. 124.
*(3) Mr. Champneys in Journal of Anatomy and Physiology, Nov., 1871,
p. 178.
*(4) Ibid., May, 1872, p. 421.
*(5) Prof. Macalister (ibid., p. 121) has tabulated his
observations, and finds that muscular abnormalities are most
frequent in the fore-arms, secondly, in the face, thirdly, in the
foot, &c.
*(6) The Rev. Dr. Haughton, after giving (Proc. R. Irish Academy,
June 27, 1864, p. 715) a remarkable case of variation in the human
flexor pollicis longus, adds, "This remarkable example shows that
man may sometimes possess the arrangement of tendons of thumb and
fingers characteristic of the macaque; but whether such a case
should be regarded as a macaque passing upwards into a man, or a man
passing downwards into a macaque, or as a congenital freak of
nature, I cannot undertake to say." It is satisfactory to hear so
capable an anatomist, and so embittered an opponent of evolutionism,
admitting even the possibility of either of his first propositions.
Prof. Macalister has also described (Proceedings Royal Irish
Academy, vol. x., 1864, p. 138) variations in the flexor pollicis
longus, remarkable from their relations to the same muscle in the
Quadrumana.
That this unknown factor is reversion to a former state of existence
may be admitted as in the highest degree probable.* It is quite
incredible that a man should through mere accident abnormally resemble
certain apes in no less than seven of his muscles, if there had been
no genetic connection between them. On the other hand, if man is
descended from some ape-like creature, no valid reason can be assigned
why certain muscles should not suddenly reappear after an interval
of many thousand generations, in the same manner as with horses,
asses, and mules, dark-coloured stripes suddenly reappear on the legs,
and shoulders, after an interval of hundreds, or more probably of
thousands of generations.
* Since the first edition of this book appeared, Mr. Wood has
published another memoir in the Philosophical Transactions, 1870, p.
83, on the varieties of the muscles of the human neck, shoulder, and
chest. He here shows how extremely variable these muscles are, and how
often and how closely the variations resemble the normal muscles of
the lower animals. He sums up by remarking, "It will be enough for
my purpose if I have succeeded in shewing the more important forms
which, when occurring as varieties in the human subject, tend to
exhibit in a sufficiently marked manner what may be considered as
proofs and examples of the Darwinian principle of reversion, or law of
inheritance, in this department of anatomical science."
These various cases of reversion are so closely related to those
of rudimentary organs given in the first chapter, that many of them
might have been indifferently introduced either there or here. Thus
a human uterus furnished with cornua may be said to represent, in a
rudimentary condition, the same organ in its normal state in certain
mammals. Some parts which are rudimentary in man, as the os coccyx
in both sexes, and the mammae in the male sex, are always present;
whilst others, such as the supracondyloid foramen, only occasionally
appear, and therefore might have been introduced under the head of
reversion. These several reversionary structures, as well as the
strictly rudimentary ones, reveal the descent of man from some lower
form in an unmistakable manner.
Correlated Variation.- In man, as in the lower animals, many
structures are so intimately related, that when one part varies so
does another, without our being able, in most cases, to assign any
reason. We cannot say whether the one part governs the other, or
whether both are governed by some earlier developed part. Various
monstrosities, as I. Geoffroy repeatedly insists, are thus
intimately connected. Homologous structures are particularly liable to
change together, as we see on the opposite sides of the body, and in
the upper and lower extremities. Meckel long ago remarked, that when
the muscles of the arm depart from their proper type, they almost
always imitate those of the leg; and so, conversely, with the
muscles of the legs. The organs of sight and hearing, the teeth and
hair, the colour of the skin and of the hair, colour and constitution,
are more or less correlated.* Professor Schaaffhausen first drew
attention to the relation apparently existing between a muscular frame
and the strongly-pronounced supra-orbital ridges, which are so
characteristic of the lower races of man.
* The authorities for these several statements are given in my
Variation of Animals and Plants under Domestication, vol. ii., pp.
320-335.
Besides the variations which can be grouped with more or less
probability under the foregoing heads, there is a large class of
variations which may be provisionally called spontaneous, for to our
ignorance they appear to arise without any exciting cause. It can,
however, be shewn that such variations, whether consisting of slight
individual differences, or of strongly-marked and abrupt deviations of
structure, depend much more on the constitution of the organism than
on the nature of the conditions to which it has been subjected.*
* This whole subject has been discussed in chap. xxiii., vol. ii. of
my Variation of Animals and Plants under Domestication.
Rate of Increase.- Civilised populations have been known under
favourable conditions, as in the United States, to double their
numbers in twenty-five years; and, according to a calculation, by
Euler, this might occur in a little over twelve years.* At the
former rate, the present population of the United States (thirty
millions), would in 657 years cover the whole terraqueous globe so
thickly, that four men would have to stand on each square yard of
surface. The primary or fundamental check to the continued increase of
man is the difficulty of gaining subsistence, and of living in
comfort. We may infer that this is the case from what we see, for
instance, in the United States, where subsistence is easy, and there
is plenty of room. If such means were suddenly doubled in Great
Britain, our number would be quickly doubled. With civilised nations
this primary check acts chiefly by restraining marriages. The
greater death-rate of infants in the poorest classes is also very
important; as well as the greater mortality, from various diseases, of
the inhabitants of crowded and miserable houses, at all ages. The
effects of severe epidemics and wars are soon counterbalanced, and
more than counterbalanced, in nations placed under favourable
conditions. Emigration also comes in aid as a temporary check, but,
with the extremely poor classes, not to any great extent.
* See the ever memorable Essay on the Principle of Population, by
the Rev. T. Malthus, vol. i. 1826. pp. 6, 517.
There is great reason to suspect, as Malthus has remarked, that
the reproductive power is actually less in barbarous, than in
civilised races. We know nothing positively on this head, for with
savages no census has been taken; but from the concurrent testimony of
missionaries, and of others who have long resided with such people, it
appears that their families are usually small, and large ones rare.
This may be partly accounted for, as it is believed, by the women
suckling their infants during a long time; but it is highly probable
that savages, who often suffer much hardships, and who do not obtain
so much nutritious food as civilised men, would be actually less
prolific. I have shewn in a former work,* that all our domesticated
quadrupeds and birds, and all our cultivated plants, are more
fertile than the corresponding species in a state of nature. It is
no valid objection to this conclusion that animals suddenly supplied
with an excess of food, or when grown very fat; and that most plants
on sudden removal from very poor to very rich soil, are rendered
more or less sterile. We might, therefore, expect that civilised
men, who in one sense are highly domesticated, would be more
prolific than wild men. It is also probable that the increased
fertility of civilised nations would become, as with our domestic
animals, an inherited character: it is at least known that with
mankind a tendency to produce twins runs in families.*(2)
* Variation of Animals and Plants under Domestication, vol ii.,
pp. 111-113, 163.
*(2) Mr. Sedgwick, British and Foreign Medico-Chirurgical Review,
July, 1863, p. 170.
Notwithstanding that savages appear to be less prolific than
civilised people, they would no doubt rapidly increase if their
numbers were not by some means rigidly kept down. The Santali, or
hill-tribes of India, have recently afforded a good illustration of
this fact; for, as shewn by Mr. Hunter,* they have increased at an
extraordinary rate since vaccination has been introduced, other
pestilences mitigated, and war sternly repressed. This increase,
however, would not have been possible had not these rude people spread
into the adjoining districts, and worked for hire. Savages almost
always marry; yet there is some prudential restraint, for they do
not commonly marry at the earliest possible age. The young men are
often required to shew that they can support a wife; and they
generally have first to earn the price with which to purchase her from
her parents. With savages the difficulty of obtaining subsistence
occasionally limits their number in a much more direct manner than
with civilised people, for all tribes periodically suffer from
severe famines. At such times savages are forced to devour much bad
food, and their health can hardly fail to be injured. Many accounts
have been published of their protruding stomachs and emaciated limbs
after and during famines. They are then, also, compelled to wander
much, and, as I was assured in Australia, their infants perish in
large numbers. As famines are periodical, depending chiefly on extreme
seasons, all tribes must fluctuate in number. They cannot steadily and
regularly increase, as there is no artificial increase in the supply
of food. Savages, when hard pressed, encroach on each other's
territories, and war is the result; but they are indeed almost
always at war with their neighbours. They are liable to many accidents
on land and water in their search for food; and in some countries they
suffer much from the larger beasts of prey. Even in India, districts
have been depopulated by the ravages of tigers.
* The Animals of Rural Bengal, by W. W. Hunter, 1868, p. 259.
Malthus has discussed these several checks, but he does not lay
stress enough on what is probably the most important of all, namely
infanticide, especially of female infants and the habit of procuring
abortion. These practices now prevail in many quarters of the world;
and infanticide seems formerly to have prevailed, as Mr. M'Lennan* has
shewn on a still more extensive scale. These practices appear to
have originated in savages recognising the difficulty, or rather the
impossibility of supporting all the infants that are born.
Licentiousness may also be added to the foregoing checks; but this
does not follow from failing means of subsistence; though there is
reason to believe that in some cases (as in Japan) it has been
intentionally encouraged as a means of keeping down the population.
* Primitive Marriage, 1865.
If we look back to an extremely remote epoch, before man had arrived
at the dignity of manhood, he would have been guided more by
instinct and less by reason than are the lowest savages at the present
time. Our early semi-human progenitors would not have practised
infanticide or polyandry; for the instincts of the lower animals are
never so perverted* as to lead them regularly to destroy their own
offspring, or to be quite devoid of jealousy. There would have been no
prudential restraint from marriage, and the sexes would have freely
united at an early age. Hence the progenitors of man would have tended
to increase rapidly; but checks of some kind, either periodical or
constant, must have kept down their numbers, even more severely than
with existing savages. What the precise nature of these checks were,
we cannot say, any more than with most other animals. We know that
horses and cattle, which are not extremely prolific animals, when
first turned loose in South America, increased at an enormous rate.
The elephant, the slowest breeder of all known animals, would in a few
thousand years stock the whole world. The increase of every species of
monkey must be checked by some means; but not, as Brehm remarks, by
the attacks of beasts of prey. No one will assume that the actual
power of reproduction in the wild horses and cattle of America, was at
first in any sensible degree increased; or that, as each district
became fully stocked, this same power was diminished. No doubt, in
this case, and in all others, many checks concur, and different checks
under different circumstances; periodical dearths, depending on
unfavourable seasons, being probably the most important of all. So
it will have been with the early progenitors of man.
* A writer in the Spectator (March 12, 1871, p. 320) comments as
follows on this passage:- "Mr. Darwin finds himself compelled to
reintroduce a new doctrine of the fall of man. He shews that the
instincts of the higher animals are far nobler than the habits of
savage races of men, and he finds himself, therefore, compelled to
re-introduce,- in a form of the substantial orthodoxy of which he
appears to be quite unconscious,- and to introduce as a scientific
hypothesis the doctrine that man's gain of knowledge was the cause
of a temporary but long-enduring moral deterioration as indicated by
the many foul customs, especially as to marriage, of savage tribes.
What does the Jewish tradition of the moral degeneration of man
through his snatching at a knowledge forbidden him by his highest
instinct assert beyond this?"
Natural Selection.- We have now seen that man is variable in body
and mind; and that the variations are induced, either directly or
indirectly, by the same general causes, and obey the same general
laws, as with the lower animals. Man has spread widely over the face
of the earth, and must have been exposed, during his incessant
migration,* to the most diversified conditions. The inhabitants of
Tierra del Fuego, the Cape of Good Hope, and Tasmania in the one
hemisphere, and of the arctic regions in the other, must have passed
through many climates, and changed their habits many times, before
they reached their present homes.*(2) The early progenitors of man
must also have tended, like all other animals, to have increased
beyond their means of subsistence; they must, therefore,
occasionally have been exposed to a struggle for existence, and
consequently to the rigid law of natural selection. Beneficial
variations of all kinds will thus, either occasionally or
habitually, have been preserved and injurious ones eliminated. I do
not refer to strongly-marked deviations of structure, which occur only
at long intervals of time, but to mere individual differences. We
know, for instance, that the muscles of our hands and feet, which
determine our powers of movement, are liable, like those of the
lower animals,*(3) to incessant variability. If then the progenitors
of man inhabiting any district, especially one undergoing some
change in its conditions, were divided into two equal bodies, the
one half which included all the individuals best adapted by their
powers of movement for gaining subsistence, or for defending
themselves, would on an average survive in greater numbers, and
procreate more offspring than the other and less well endowed half.
* See some good remarks to this effect by W. Stanley Jevons, "A
Deduction from Darwin's Theory," Nature 1869, p. 231.
*(2) Latham, Man and his Migrations, 1851, p. 135.
*(3) Messrs. Murie and Mivart in their "Anatomy of the Lemuroidea"
(Transact. Zoolog. Soc., vol. vii., 1869, pp. 96-98) say, " some
muscles are so irregular in their distribution that they cannot be
well classed in any of the above groups." These muscles differ even on
the opposite sides of the same individual.
Man in the rudest state in which he now exists is the most
dominant animal that has ever appeared on this earth. He has spread
more widely than any other highly organised form: and all others
have yielded before him. He manifestly owes this immense superiority
to his intellectual faculties, to his social habits, which lead him to
aid and defend his fellows, and to his corporeal structure. The
supreme importance of these characters has been proved by the final
arbitrament of the battle for life. Through his powers of intellect,
articulate language has been evolved; and on this his wonderful
advancement has mainly depended. As Mr. Chauncey Wright remarks: "A
psychological analysis of the faculty of language shews, that even the
smallest proficiency in it might require more brain power than the
greatest proficiency in any other direction."* He has invented and
is able to use various weapons, tools, traps, &c., with which he
defends himself, kills or catches prey, and otherwise obtains food. He
has made rafts or canoes for fishing or crossing over to
neighbouring fertile islands. He has discovered the art of making
fire, by which hard and stringy roots can be rendered digestible,
and poisonous roots or herbs innocuous. This discovery of fire,
probably the greatest ever made by man, excepting language, dates from
before the dawn of history. These several inventions, by which man
in the rudest state has become so pre-eminent, are the direct
results of the development of his powers of observation, memory,
curiosity, imagination, and reason. I cannot, therefore, understand
how it is that Mr. Wallace*(2) maintains, that "natural selection
could only have endowed the savage with a brain a little superior to
that of an ape."
* "Limits of Natural Selection," North American Review, Oct.,
1870, p. 295.
*(2) Quarterly Review, April, 1869, p. 392. This subject is more
fully discussed in Mr. Wallace's Contributions to the Theory of
Natural Selection, 1870, in which all the essays referred to in this
work are re-published. The "Essay on Man," has been ably criticised by
Prof. Claparede, one of the most distinguished zoologists in Europe,
in an article published in the Bibliotheque Universelle, June, 1870.
The remark quoted in my text will surprise every one who has read
Mr. Wallace's celebrated paper on "The Origin of Human Races Deduced
from the Theory of Natural Selection," originally published in the
Anthropological Review, May, 1864, p. clviii. I cannot here resist
quoting a most just remark by Sir J. Lubbock (Prehistoric Times, 1865,
p. 479) in reference to this paper, namely, that Mr. Wallace, "with
characteristic unselfishness, ascribes it (i. e. the idea of natural
selection) unreservedly to Mr. Darwin, although, as is well known,
he struck out the idea independently, and published it, though not
with the same elaboration, at the same time."
Although the intellectual powers and social habits of man are of
paramount importance to him, we must not underrate the importance of
his bodily structure, to which subject the remainder of this chapter
will be devoted; the development of the intellectual and social or
moral faculties being discussed in a later chapter.
Even to hammer with precision is no easy matter, as every one who
has tried to learn carpentry will admit. To throw a stone with as true
an aim as a Fuegian in defending himself, or in killing birds,
requires the most consummate perfection in the correlated action of
the muscles of the hand, arm, and shoulder, and, further, a fine sense
of touch. In throwing a stone or spear, and in many other actions, a
man must stand firmly on his feet; and this again demands the
perfect co-adaptation of numerous muscles. To chip a flint into the
rudest tool, or to form a barbed spear or hook from a bone, demands
the use of a perfect hand; for, as a most capable judge, Mr.
Schoolcraft,* remarks, the shaping fragments of stone into knives,
lances, or arrow-heads, shews "extraordinary ability and long
practice." This is to a great extent proved by the fact that
primeval men practised a division of labour; each man did not
manufacture his own flint tools or rude pottery, but certain
individuals appear to have devoted themselves to such work, no doubt
receiving in exchange the produce of the chase. Archaeologists are
convinced that an enormous interval of time elapsed before our
ancestors thought of grinding chipped flints into smooth tools. One
can hardly doubt, that a man-like animal who possessed a hand and
arm sufficiently perfect to throw a stone with precision, or to form a
flint into a rude tool, could, with sufficient practice, as far as
mechanical skill alone is concerned, make almost anything which a
civilised man can make. The structure of the hand in this respect
may be compared with that of the vocal organs, which in the apes are
used for uttering various signal-cries, or, as in one genus, musical
cadences; but in man the closely similar vocal organs have become
adapted through the inherited effects of use for the utterance of
articulate language.
* Quoted by Mr. Lawson Tait in his "Law of Natural Selection,"
Dublin Quarterly Journal of Medical Science, Feb., 1869. Dr. Keller is
likewise quoted to the same effect.
Turning now to the nearest allies of men, and therefore to the
best representatives of our early progenitors, we find that the
hands of the Quadrumana are constructed on the same general pattern as
our own, but are far less perfectly adapted for diversified uses.
Their hands do not serve for locomotion so well as the feet of a
dog; as may be seen in such monkeys as the chimpanzee and orang, which
walk on the outer margins of the palms, or on the knuckles.* Their
hands, however, are admirably adapted for climbing trees. Monkeys
seize thin branches or ropes, with the thumb on one side and the
fingers and palm on the other, in the same manner as we do. They can
thus also lift rather large objects, such as the neck of a bottle,
to their mouths. Baboons turn over stones, and scratch up roots with
their hands. They seize nuts, insects, or other small objects with the
thumb in opposition to the fingers, and no doubt they thus extract
eggs and young from the nests of birds. American monkeys beat the wild
oranges on the branches until the rind is cracked, and then tear it
off with the fingers of the two hands. In a wild state they break open
hard fruits with stones. Other monkeys open mussel-shells with the two
thumbs. With their fingers they pull out thorns and burs, and hunt for
each other's parasites. They roll down stones, or throw them at
their enemies: nevertheless, they are clumsy in these various actions,
and, as I have myself seen, are quite unable to throw a stone with
precision.
* Owen, Anatomy of Vertebrates, vol. iii., p. 71.
It seems to me far from true that because "objects are grasped
clumsily" by monkeys, "a much less specialised organ of prehension"
would have served them* equally well with their present hands. On
the contrary, I see no reason to doubt that more perfectly constructed
hands would have been an advantage to them, provided that they were
not thus rendered less fitted for climbing trees. We may suspect
that a hand as perfect as that of man would have been
disadvantageous for climbing; for the most arboreal monkeys in the
world, namely, Ateles in America, Colobus in Africa, and Hylobates
in Asia, are either thumbless, or their toes partially cohere, so that
their limbs are converted into mere grasping hooks.*(2)
* Quarterly Review, April, 1869, p. 392.
*(2) In Hylobates syndactylus, as the name expresses, two of the
toes regularly cohere; and this, as Mr. Blyth informs me, is
occasionally the case with the toes of H. agilis, lar, and
leuciscus. Colobus is strictly arboreal and extraordinarily active
(Brehm, Illustriertes Thierleben, B. i., s. 50), but whether a
better climber than the species of the allied genera, I do not know.
It deserves notice that the feet of the sloths, the most arboreal
animals in the world, are wonderfully hooklike.
As soon as some ancient member in the great series of the primates
came to be less arboreal, owing to a change in its manner of procuring
subsistence, or to some change in the surrounding conditions, its
habitual manner of progression would have been modified: and thus it
would have been rendered more strictly quadrupedal or bipedal. Baboons
frequent hilly and rocky districts, and only from necessity climb high
trees;* and they have acquired almost the gait of a dog. Man alone has
become a biped; and we can, I think, partly see how he has come to
assume his erect attitude, which forms one of his most conspicuous
characters. Man could not have attained his present dominant
position in the world without the use of his hands, which are so
admirably adapted to act in obedience to his will. Sir C. Bell*(2)
insists that "the hand supplies all instruments, and by its
correspondence with the intellect gives him universal dominion." But
the hands and arms could hardly have become perfect enough to have
manufactured weapons, or to have hurled stones and spears with a
true aim, as long as they were habitually used for locomotion and
for supporting the whole weight of the body, or, as before remarked,
so long as they were especially fitted for climbing trees. Such
rough treatment would also have blunted the sense of touch, on which
their delicate use largely depends. From these causes alone it would
have been an advantage to man to become a biped; but for many
actions it is indispensable that the arms and whole upper part of
the body should be free; and he must for this end stand firmly on
his feet. To gain this great advantage, the feet have been rendered
flat; and the great toe has been peculiarly modified, though this
has entailed the almost complete loss of its power of prehension. It
accords with the principle of the division of physiological labour,
prevailing throughout the animal kingdom, that as the hands became
perfected for prehension, the feet should have become perfected for
support and locomotion. With some savages, however, the foot has not
altogether lost its prehensile power, as shewn by their manner of
climbing trees, and of using them in other ways.*(3)
* Brehm, Illustriertes Thierleben, B. i., s. 80.
*(2) "The Hand," &c., Bridgewater Treatise, 1833, p. 38.
*(3) Haeckel has an excellent discussion on the steps by which
man became a biped: Naturliche Schopfungsgeschicte, 1868, s. 507.
Dr. Buchner (Conferences sur la Theorie Darwinienne, 1869, p. 135) has
given good cases of the use of the foot as a prehensile organ by
man; and has also written on the manner of progression of the higher
apes, to which I allude in the following paragraph: see also Owen
(Anatomy of Vertebrates, vol. iii., p. 71) on this latter subject.
If it be an advantage to man to stand firmly on his feet and to have
his hands and arms free, of which, from his pre-eminent success in the
battle of life, there can be no doubt, then I can see no reason why it
should not have been advantageous to the progenitors of man to have
become more and more erect or bipedal. They would thus have been
better able to defend themselves with stones or clubs, to attack their
prey, or otherwise to obtain food. The best built individuals would in
the long run have succeeded best, and have survived in larger numbers.
If the gorilla and a few allied forms had become extinct, it might
have been argued, with great force and apparent truth, that an
animal could not have been gradually converted from a quadruped into a
biped, as all the individuals in an intermediate condition would
have been miserably ill-fitted for progression. But we know (and
this is well worthy of reflection) that the anthropomorphous apes
are now actually in an intermediate condition; and no one doubts
that they are on the whole well adapted for their conditions of
life. Thus the gorilla runs with a sidelong shambling gait, but more
commonly progresses by resting on its bent hands. The long-armed
apes occasionally use their arms like crutches, swinging their
bodies forward between them, and some kinds of Hylobates, without
having been taught, can walk or run upright with tolerable
quickness; yet they move awkwardly, and much less securely than man.
We see, in short, in existing monkeys a manner of progression
intermediate between that of a quadruped and a biped; but, as an
unprejudiced judge* insists, the anthropomorphous apes approach in
structure more nearly to the bipedal than to the quadrupedal type.
* Prof. Broca, "La Constitution des vertebres caudales"; La Revue
d'Anthropologie, 1872, p. 26, (separate copy).
As the progenitors of man became more and more erect, with their
hands and arms more and more modified for prehension and other
purposes, with their feet and legs at the same time transformed for
firm support and progression, endless other changes of structure would
have become necessary. The pelvis would have to be broadened, the
spine peculiarly curved, and the head fixed in an altered position,
all which changes have been attained by man. Prof. Schaaffhausen*
maintains that "the powerful mastoid processes of the human skull
are the result of his erect position"; and these processes are
absent in the orang, chimpanzee, &c., and are smaller in the gorilla
than in man. Various other structures, which appear connected with
man's erect position, might here have been added. It is very difficult
to decide how far these correlated modifications are the result of
natural selection, and how far of the inherited effects of the
increased use of certain parts, or of the action of one part on
another. No doubt these means of change often co-operate: thus when
certain muscles, and the crests of bone to which they are attached,
become enlarged by habitual use, this shews that certain actions are
habitually performed and must be serviceable. Hence the individuals
which performed them best, would tend to survive in greater numbers.
* "On the Primitive Form of the Skull," translated in
Anthropological Review, Oct., 1868, p. 428. Owen (Anatomy of
Vertebrates, vol. ii., 1866, p. 551) on the mastoid processes in the
higher apes.
The free use of the arms and hands, partly the cause and partly
the result of man's erect position, appears to have led in an indirect
manner to other modifications of structure. The early male forefathers
of man were, as previously stated, probably furnished with great
canine teeth; but as they gradually acquired the habit of using
stones, clubs, or other weapons, for fighting with their enemies or
rivals, they would use their jaws and teeth less and less. In this
case, the jaws, together with the teeth, would become reduced in size,
as we may feel almost sure from innumerable analogous cases. In a
future chapter we shall meet with a closely parallel case, in the
reduction or complete disappearance of the canine teeth in male
ruminants, apparently in relation with the development of their horns;
and in horses, in relation to their habit of fighting with their
incisor teeth and hoofs.
In the adult male anthropomorphous apes, as Rutimeyer,* and
others, have insisted, it is the effect on the skull of the great
development of the jaw-muscles that causes it to differ so greatly
in many respects from that of man, and has given to these animals "a
truly frightful physiognomy." Therefore, as the jaws and teeth in
man's progenitors gradually become reduced in size, the adult skull
would have come to resemble more and more that of existing man. As
we shall hereafter see, a great reduction of the canine teeth in the
males would almost certainly affect the teeth of the females through
inheritance.
* Die Grenzen der Thierwelt, eine Betrachtung zu Darwin's Lehre,
1868, s. 51.
As the various mental faculties gradually developed themselves the
brain would almost certainly become larger. No one, I presume,
doubts that the large proportion which the size of man's brain bears
to his body, compared to the same proportion in the gorilla or
orang, is closely connected with his higher mental powers. We meet
with closely analogous facts with insects, for in ants the cerebral
ganglia are of extraordinary dimensions, and in all the Hymenoptera
these ganglia are many times larger than in the less intelligent
orders, such as beetles.* On the other hand, no one supposes that
the intellect of any two animals or of any two men can be accurately
gauged by the cubic contents of their skulls. It is certain that there
may be extraordinary mental activity with an extremely small
absolute mass of nervous matter: thus the wonderfully diversified
instincts, mental powers, and affections of ants are notorious, yet
their cerebral ganglia are not so large as the quarter of a small
pin's head. Under this point of view, the brain of an ant is one of
the most marvellous atoms of matter in the world, perhaps more so than
the brain of a man.
* Dujardin, Annales des Sciences Nat., 3rd series, Zoolog., tom.
xiv., 1850, p. 203. See also Mr. Lowne, Anatomy and Phys. of the Musca
vomitoria, 1870, p. 14. My son, Mr. F. Darwin, dissected for me the
cerebral ganglia of the Formica rufa.
The belief that there exists in man some close relation between
the size of the brain and the development of the intellectual
faculties is supported by the comparison of the skulls of savage and
civilised races, of ancient and modern people, and by the analogy of
the whole vertebrate series. Dr. J. Barnard Davis has proved,* by many
careful measurements, that the mean internal capacity of the skull
in Europeans is 92.3 cubic inches; in Americans 87.5; in Asiatics
87.1; and in Australians only 81.9 cubic inches. Professor Broca*(2)
found that the nineteenth century skulls from graves in Paris were
larger than those from vaults of the twelfth century, in the
proportion of 1484 to 1426; and that the increased size, as
ascertained by measurements, was exclusively in the frontal part of
the skull- the seat of the intellectual faculties. Prichard is
persuaded that the present inhabitants of Britain have "much more
capacious braincases" than the ancient inhabitants. Nevertheless, it
must be admitted that some skulls of very high antiquity, such as
the famous one of Neanderthal, are well developed and capacious.*(3)
With respect to the lower animals, M. E. Lartet,*(4) by comparing
the crania of tertiary and recent mammals belonging to the same
groups, has come to the remarkable conclusion that the brain is
generally larger and the convolutions are more complex in the more
recent forms. On the other hand, I have shewn*(5) that the brains of
domestic rabbits are considerably reduced in bulk, in comparison
with those of the wild rabbit or hare; and this may be attributed to
their having been closely confined during many generations, so that
they have exerted their intellect, instincts, senses and voluntary
movements but little.
* Philosophical Transactions, 1869, p. 513.
*(2) "Les Selections," M. P. Broca, Revue d'Anthropologie,, 1873;
see also, as quoted in C. Vogt's Lectures on Man, Engl. translat.,
1864, pp. 88, 90. Prichard, Physical History of Mankind, vol. i.,
1838, p. 305.
*(3) In the interesting article just referred to, Prof. Broca has
well remarked, that in civilised nations, the average capacity of
the skull must be lowered by the preservation of a considerable number
of individuals, weak in mind and body, who would have been promptly
eliminated in the savage state. On the other hand, with savages, the
average includes only the more capable individuals, who have been able
to survive under extremely hard conditions of life. Broca thus
explains the otherwise inexplicable fact, that the mean capacity of
the skull of the ancient troglodytes of Lozere is greater than that of
modern Frenchmen.
*(4) Comptes-rendus des Sciences, &c., June 1, 1868.
*(5) The Variation of Animals and Plants under Domestication, vol.
i., pp. 124-129.
The gradually increasing weight of the brain and skull in man must
have influenced the development of the supporting spinal column,
more especially whilst he was becoming erect. As this change of
position was being brought about, the internal pressure of the brain
will also have influenced the form of the skull; for many facts shew
how easily the skull is thus effected. Ethnologists believe that it is
modified by the kind of cradle in which infants sleep. Habitual spasms
of the muscles, and a cicatrix from a severe burn, have permanently
modified the facial bones. In young persons whose heads have become
fixed either sideways or backwards, owing to disease, one of the two
eyes has changed its position, and the shape of the skull has been
altered apparently by the pressure of the brain in a new direction.* I
have shewn that with long-eared rabbits even so trifling a cause as
the lopping forward of one ear drags forward almost every bone of
the skull on that side; so that the bones on the opposite side no
longer strictly correspond. Lastly, if any animal were to increase
or diminish much in general size, without any change in its mental
powers, or if the mental powers were to be much increased or
diminished, without any great change in the size of the body, the
shape of the skull would almost certainly be altered. I infer this
from my observations on domestic rabbits, some kinds of which have
become very much larger than the wild animal, whilst others have
retained nearly the same size, but in both cases the brain has been
much reduced relatively to the size of the body. Now I was at first
much surprised on finding that in all these rabbits the skull had
become elongated or dolichocephalic; for instance, of two skulls of
nearly equal breadth, the one from a wild rabbit and the other from
a large domestic kind, the former was 3.15 and the latter 4.3 inches
in length.*(2) One of the most marked distinctions in different
races of men is that the skull in some is elongated, and in others
rounded; and here the explanation suggested by the case of the rabbits
may hold good; for Welcker finds that short "men incline more to
brachycephaly, and tall men to dolichocephaly";*(3) and tall men may
be compared with the larger and longer-bodied rabbits, all of which
have elongated skulls or are dolichocephalic.
* Schaaffhausen gives from Blumenbach and Busch, the cases of the
spasms and cicatrix in Anthropological Review, Oct., 1868, p. 420. Dr.
Jarrold (Anthropologia, 1808, pp. 115, 116) adduces from Camper and
from his own observations, cases of the modification of the skull from
the head being fixed in an unnatural position. He believes that in
certain trades, such as that of a shoemaker, where the head is
habitually held forward, the forehead becomes more rounded and
prominent.
*(2) Variation of Animals and Plants under Domestication, vol. i.,
p. 117, on the elongation of the skull; p. 119, on the effect of the
lopping of one ear.
*(3) Quoted by Schaaffhausen, in Anthropological Review, Oct., 1868,
p. 419.
From these several facts we can understand, to a certain extent, the
means by which the great size and more or less rounded form of the
skull have been acquired by man; and these are characters eminently
distinctive of him in comparison with the lower animals.
Another most conspicuous difference between man and the lower
animals is the nakedness of his skin. Whales and porpoises
(Cetacea), dugongs (Sirenia) and the hippopotamus are naked; and
this may be advantageous to them for gliding through the water; nor
would it be injurious to them from the loss of warmth, as the species,
which inhabit the colder regions, are protected by a thick layer of
blubber, serving the same purpose as the fur of seals and otters.
Elephants and rhinoceroses are almost hairless; and as certain extinct
species, which formerly lived under an arctic climate, were covered
with long wool or hair, it would almost appear as if the existing
species of both genera had lost their hairy covering from exposure
to heat. This appears the more probable, as the elephants in India
which live on elevated and cool districts are more hairy* than those
on the lowlands. May we then infer that man became divested of hair
from having aboriginally inhabited some tropical land? That the hair
is chiefly retained in the male sex on the chest and face, and in both
sexes at the junction of all four limbs with the trunk, favours this
inference- on the assumption that the hair was lost before man
became erect; for the parts which now retain most hair would then have
been most protected from the heat of the sun. The crown of the head,
however, offers a curious exception, for at all times it must have
been one of the most exposed parts, yet it is thickly clothed with
hair. The fact, however, that the other members of the order of
primates, to which man belongs, although inhabiting various hot
regions, are well clothed with hair, generally thickest on the upper
surface,*(2) is opposed to the supposition that man became naked
through the action of the sun. Mr. Belt believes*(3) that within the
tropies it is an advantage to man to be destitute of hair, as he is
thus enabled to free himself of the multitude of ticks (acari) and
other parasites, with which he is often infested, and which
sometimes cause ulceration. But whether this evil is of sufficient
magnitude to have led to the denudation of his body through natural
selection, may be doubted, since none of the many quadrupeds
inhabiting the tropics have, as far as I know, acquired any
specialised means of relief. The view which seems to me the most
probable is that man, or rather primarily woman, became divested of
hair for ornamental purposes, as we shall see under Sexual
Selection; and, according to this belief, it is not surprising that
man should differ so greatly in hairiness from all other primates, for
characters, gained through sexual selection, often differ to an
extraordinary degree in closely related forms.
* Owen, Anatomy of Vertebrates, vol. iii., p. 619.
*(2) Isidore Geoffroy St-Hilaire remarks (Histoire Nat. Generale,
tom. ii., 1859, pp. 215-217) on the head of man being covered with
long hair; also on the upper surfaces of monkeys and of other
mammals being more thickly clothed than the lower surfaces. This has
likewise been observed by various authors. Prof. P. Gervais
(Histoire Nat. des Mammiferes, tom. i., 1854, p. 28), however,
states that in the gorilla the hair is thinner on the back, where it
is partly rubbed off, than on the lower surface.
*(3) The Naturalist in Nicaragua, 1874, p. 209. As some confirmation
of Mr. Belt's view, I may quote the following passage from Sir W.
Denison (Varieties of Vice-Regal Life, vol. i., 1870, p. 440): "It
is said to be a practice with the Australians, when the vermin get
troublesome, to singe themselves."
According to a popular impression, the absence of a tail is
eminently distinctive of man; but as those apes which come nearest
to him are destitute of this organ, its disappearance does not
relate exclusively to man. The tail often differs remarkably in length
within the same genus: thus in some species of Macacus it is longer
than the whole body, and is formed of twenty-four vertebrae; in others
it consists of a scarcely visible stump, containing only three or four
vertebrae. In some kinds of baboons there are twenty-five, whilst in
the mandrill there are ten very small stunted caudal vertebrae, or,
according to Cuvier,* sometimes only five. The tail, whether it be
long or short, almost always tapers towards the end; and this, I
presume, results from the atrophy of the terminal muscles, together
with their arteries and nerves, through disuse, leading to the atrophy
of the terminal bones. But no explanation can at present be given of
the great diversity which often occurs in its length. Here, however,
we are more specially concerned with the complete external
disappearance of the tail. Professor Broca has recently shewn*(2) that
the tail in all quadrupeds consists of two portions, generally
separated abruptly from each other; the basal portion consists of
vertebrae, more or less perfectly channelled and furnished with
apophyses like ordinary vertebrae; whereas those of the terminal
portion are not channelled, are almost smooth, and scarcely resemble
true vertebrae. A tail, though not externally visible, is really
present in man and the anthropomorphous apes, and is constructed on
exactly the same pattern in both. In the terminal portion the
vertabrae, constituting the os coccyx, are quite rudimentary, being
much reduced in size and number. In the basal portion, the vertebrae
are likewise few, are united firmly together, and are arrested in
development; but they have been rendered much broader and flatter than
the corresponding vertebrae in the tails of other animals: they
constitute what Broca calls the accessory sacral vertebrae. These
are of functional importance by supporting certain internal parts
and in other ways; and their modification is directly connected with
the erect or semi-erect attitude of man and the anthropomorphous apes.
This conclusion is the more trustworthy, as Broca formerly held a
different view, which he has now abandoned. The modification,
therefore, of the basal caudal vertebrae in man and the higher apes
may have been effected, directly or indirectly, through natural
selection.
* Mr. St. George Mivart, Proc. Zoolog. Soc., 1865, pp. 562, 583. Dr.
J. E. Gray, Cat. Brit. Mus: " Skeletons." Owen, Anatomy of
Vertebrates, vol. ii., p. 517. Isidore Geoffroy, Hist. Nat. Gen., tom.
ii., p. 244.
*(2) Revue d'Anthropologie, 1872; "La Constitution des vertebres
caudales."
But what are we to say about the rudimentary and variable
vertebrae of the terminal portion of the tail, forming the os
coccyx? A notion which has often been, and will no doubt again be
ridiculed, namely, that friction has had something to do with the
disappearance of the external portion of the tail, is not so
ridiculous as it at first appears. Dr. Anderson* states that the
extremely short tail of Macacus brunneus is formed of eleven
vertebrae, including the imbedded basal ones. The extremity is
tendinous and contains no vertebrae; this is succeeded by five
rudimentary ones, so minute that together they are only one line and a
half in length, and these are permanently bent to one side in the
shape of a hook. The free part of the tail, only a little above an
inch in length, includes only four more small vertebrae. This short
tail is carried erect; but about a quarter of its total length is
doubled on to itself to the left; and this terminal part, which
includes the hook-like portion, serves "to fill up the interspace
between the upper divergent portion of the callosities"; so that the
animal sits on it, and thus renders it rough and callous. Dr. Anderson
thus sums up his observations: "These facts seem to me to have only
one explanation; this tail, from its short size, is in the monkey's
way when it sits down, and frequently becomes placed under the
animal while it is in this attitude; and from the circumstance that it
does not extend beyond the extremity of the ischial tuberosities, it
seems as if the tail originally had been bent round by the will of the
animal, into the interspace between the callosities, to escape being
pressed between them and the ground, and that in time the curvature
became permanent, fitting in of itself when the organ happens. to be
sat upon." Under these circumstances it is not surprising that the
surface of the tail should have been roughened and rendered callous,
and Dr. Murie,*(2) who carefully observed this species in the
Zoological Gardens, as well as three other closely allied forms with
slightly longer tails, says that when the animal sits down, the tail
"is necessarily thrust to one side of the buttocks; and whether long
or short its root is consequently liable to be rubbed or chafed." As
we now have evidence that mutilations occasionally produce an
inherited effect,*(3) it is not very improbable that in short-tailed
monkeys, the projecting part of the tail, being functionally
useless, should after many generations have become rudimentary and
distorted, from being continually rubbed and chafed. We see the
projecting part in this condition in the Macacus brunneus, and
absolutely aborted in the M. ecaudatus and in several of the higher
apes. Finally, then, as far as we can judge, the tail has
disappeared in man and the anthropomorphous apes, owing to the
terminal portion having been injured by friction during a long lapse
of time; the basal and embedded portion having been reduced and
modified, so as to become suitable to the erect or semi-erect
position.
* Proceedings Zoological Society, 1872, p. 210.
*(2) Proceedings Zoological Society, 1872, p. 786.
*(3) I allude to Dr. Brown-Sequard's observations on the transmitted
effect of an operation causing epilepsy in guinea-pigs, and likewise
more recently on the analogous effects of cutting the sympathetic
nerve in the neck. I shall hereafter have occasion to refer to Mr.
Salvin's interesting case of the apparently inherited effects of
motmots biting off the barbs of their own tail-feathers. See also on
the general subject Variation of Animals and Plants under
Domestication, vol. ii., pp. 22-24.
I have now endeavoured to shew that some of the most distinctive
characters of man have in all probability been acquired, either
directly, or more commonly indirectly, through natural selection. We
should bear in mind that modifications in structure or constitution
which do not serve to adapt an organism to its habits of life, to
the food which it consumes, or passively to the surrounding
conditions, cannot have been thus acquired. We must not, however, be
too confident in deciding what modifications are of service to each
being: we should remember how little we know about the use of many
parts, or what changes in the blood or tissues may serve to fit an
organism for a new climate or new kinds of food. Nor must we forget
the principle of correlation, by which, as Isidore Geoffroy has
shewn in the case of man, many strange deviations of structure are
tied together. Independently of correlation, a change in one part
often leads, through the increased or decreased use of other parts, to
other changes of a quite unexpected nature. It is also well to reflect
on such facts, as the wonderful growth of galls on plants caused by
the poison of an insect, and on the remarkable changes of colour in
the plumage of parrots when fed on certain fishes, or inoculated
with the poison of toads;* for we can thus see that the fluids of
the system, if altered for some special purpose, might induce other
changes. We should especially bear in mind that modifications acquired
and continually used during past ages for some useful purpose, would
probably become firmly fixed, and might be long inherited.
* The Variation of Animals and Plants under Domestication, vol. ii.,
pp. 280, 282.
Thus a large yet undefined extension may safely be given to the
direct and indirect results of natural selection; but I now admit,
after reading the essay by Nageli on plants, and the remarks by
various authors with respect to animals, more especially those
recently made by Professor Broca, that in the earlier editions of my
Origin of Species I perhaps attributed too much to the action of
natural selection or the survival of the fittest. I have altered the
fifth edition of the Origin so as to confine my remarks to adaptive
changes of structure; but I am convinced, from the light gained during
even the last few years, that very many structures which now appear to
us useless, will hereafter be proved to be useful, and will
therefore come within the range of natural selection. Nevertheless,
I did not formerly consider sufficiently the existence of
structures, which, as far as we can at present judge, are neither
beneficial nor injurious; and this I believe to be one of the greatest
oversights as yet detected in my work. I may be permitted to say, as
some excuse, that I had two distinct objects in view; firstly, to shew
that species had not been separately created, and secondly, that
natural selection had been the chief agent of change, though largely
aided by the inherited effects of habit, and slightly by the direct
action of the surrounding conditions. I was not, however, able to
annul the influence of my former belief, then almost universal, that
each species had been purposely created; and this led to my tacit
assumption that every detail of structure, excepting rudiments, was of
some special, though unrecognised, service. Any one with this
assumption in his mind would naturally extend too far the action of
natural selection, either during past or present times. Some of
those who admit the principle of evolution, but reject natural
selection, seem to forget, when criticising my book, that I had the
above two objects in view; hence if I have erred in giving to
natural selection great power, which I am very far from admitting,
or in having exaggerated its power, which is in itself probable, I
have at least, as I hope, done good service in aiding to overthrow the
dogma of separate creations.
It is, as I can now see, probable that all organic beings, including
man, possess peculiarities of structure, which neither are now, nor
were formerly of any service to them, and which, therefore, are of
no physiological importance. We know not what produces the
numberless slight differences between the individuals of each species,
for reversion only carries the problem a few steps backwards, but each
peculiarity must have had its efficient cause. If these causes,
whatever they may be, were to act more uniformly and energetically
during a lengthened period (and against this no reason can be
assigned), the result would probably be not a mere slight individual
difference, but a well-marked and constant modification, though one of
no physiological importance. Changed structures, which are in no way
beneficial, cannot be kept uniform through natural selection, though
the injurious will be thus eliminated. Uniformity of character
would, however, naturally follow from the assumed uniformity of the
exciting causes, and likewise from the free intercrossing of many
individuals. During successive periods, the same organism might in
this manner acquire successive modifications, which would be
transmitted in a nearly uniform state as long as the exciting causes
remained the same and there was free intercrossing. With respect to
the exciting causes we can only say, as when speaking of so-called
spontaneous variations, that they relate much more closely to the
constitution of the varying organism, than to the nature of the
conditions to which it has been subjected.
Conclusion.- In this chapter we have seen that as man at the present
day is liable, like every other animal, to multiform individual
differences or slight variations, so no doubt were the early
progenitors of man; the variations being formerly induced by the
same general causes, and governed by the same general and complex laws
as at present. As all animals tend to multiply beyond their means of
subsistence, so it must have been with the progenitors of man; and
this would inevitably lead to a struggle for existence and to
natural selection. The latter process would be greatly aided by the
inherited effects of the increased use of parts, and these two
processes would incessantly react on each other. It appears, also,
as we shall hereafter see, that various unimportant characters have
been acquired by man through sexual selection. An unexplained residuum
of change must be left to the assumed uniform action of those
unknown agencies, which occasionally induce strongly marked and abrupt
deviations of structure in our domestic productions.
Judging from the habits of savages and of the greater number of
the Quadrumana, primeval men, and even their ape-like progenitors,
probably lived in society. With strictly social animals, natural
selection sometimes acts on the individual, through the preservation
of variations which are beneficial to the community. A community which
includes a large number of well-endowed individuals increases in
number, and is victorious over other less favoured ones; even although
each separate member gains no advantage over the others of the same
community. Associated insects have thus acquired many remarkable
structures, which are of little or no service to the individual,
such as the pollen-collecting apparatus, or the sting of the
worker-bee, or the great jaws of soldier-ants. With the higher
social animals, I am not aware that any structure has been modified
solely for the good of the community, though some are of secondary
service to it. For instance, the horns of ruminants and the great
canine teeth of baboons appear to have been acquired by the males as
weapons for sexual strife, but they are used in defence of the herd or
troop. In regard to certain mental powers the case, as we shall see in
the fifth chapter, is wholly different; for these faculties have
been chiefly, or even exclusively, gained for the benefit of the
community, and the individuals thereof have at the same time gained an
advantage indirectly.
It has often been objected to such views as the foregoing, that
man is one of the most helpless and defenceless creatures in the
world; and that during his early and less well-developed condition, he
would have been still more helpless. The Duke of Argyll, for instance,
insists* that "the human frame has diverged from the structure of
brutes, in the direction of greater physical helplessness and
weakness. That is to say, it is a divergence which of all others it is
most impossible to ascribe to mere natural selection." He adduces
the naked and unprotected state of the body, the absence of great
teeth or claws for defence, the small strength and speed of man, and
his slight power of discovering food or of avoiding danger by smell.
To these deficiencies there might be added one still more serious,
namely, that he cannot climb quickly, and so escape from enemies.
The loss of hair would not have been a great injury to the inhabitants
of a warm country. For we know that the unclothed Fuegians can exist
under a wretched climate. When we compare the defenceless state of man
with that of apes, we must remember that the great canine teeth with
which the latter are provided, are possessed in their full development
by the males alone, and are chiefly used by them for fighting with
their rivals; yet the females, which are not thus provided, manage
to survive.
* Primeval Man, 1869, p. 66.
In regard to bodily size or strength, we do not know whether man
is descended from some small species, like the chimpanzee, or from one
as powerful as the gorilla; and, therefore, we cannot say whether
man has become larger and stronger, or smaller and weaker, than his
ancestors. We should, however, bear in mind that an animal
possessing great size, strength, and ferocity, and which, like the
gorilla, could defend itself from all enemies, would not perhaps
have become social: and this would most effectually have checked the
acquirement of the higher mental qualities, such as sympathy and the
love of his fellows. Hence it might have been an immense advantage
to man to have sprung from some comparatively weak creature.
The small strength and speed of man, his want of natural weapons,
&c., are more than counterbalanced, firstly, by his intellectual
powers, through which he has formed for himself weapons, tools, &c.,
though still remaining in a barbarous state, and, secondly, by his
social qualities which lead him to give and receive aid from his
fellow-men. No country in the world abounds in a greater degree with
dangerous beasts than southern Africa; no country presents more
fearful physical hardships than the arctic regions; yet one of the
puniest of races, that of the bushmen, maintains itself in southern
Africa, as do the dwarfed Esquimaux in the arctic regions. The
ancestors of man were, no doubt, inferior in intellect, and probably
in social disposition, to the lowest existing savages; but it is quite
conceivable that they might have existed, or even flourished, if
they had advanced in intellect, whilst gradually losing their
brute-like powers such as that of climbing trees, &c. But these
ancestors would not have been exposed to any special danger, even if
far more helpless and defenceless than any existing savages, had
they inhabited some warm continent or large island, such as Australia,
New Guinea, or Borneo, which is now the home of the orang. And natural
selection arising from the competition of tribe with tribe, in some
such large area as one of these, together with the inherited effects
of habit, would, under favourable conditions, have sufficed to raise
man to his present high position in the organic scale.
CHAPTER III.
COMPARISON OF THE MENTAL POWERS OF MAN AND THE LOWER ANIMALS.
WE HAVE seen in the last two chapters that man bears in his bodily
structure clear traces of his descent from some lower form; but it may
be urged that, as man differs so greatly in his mental power from
all other animals, there must be some error in this conclusion. No
doubt the difference in this respect is enormous, even if we compare
the mind of one of the lowest savages, who has no words to express any
number higher than four, and who uses hardly any abstract terms for
common objects or for the affections,* with that of the most highly
organised ape. The difference would, no doubt, still remain immense,
even if one of the higher apes had been improved or civilised as
much as a dog has been in comparison with its parent-form, the wolf or
jackal. The Fuegians rank amongst the lowest barbarians; but I was
continually struck with surprise how closely the three natives on
board H. M. S. Beagle, who had lived some years in England, and
could talk a little English, resembled us in disposition and in most
of our mental faculties. If no organic being excepting man had
possessed any mental power, or if his powers had been of a wholly
different nature from those of the lower animals, then we should never
have been able to convince ourselves that our high faculties had
been gradually developed. But it can be shewn that there is no
fundamental difference of this kind. We must also admit that there
is a much wider interval in mental power between one of the lowest
fishes, as a lamprey or lancelet, and one of the higher apes, than
between an ape and man; yet this interval is filled up by numberless
gradations.
* See the evidence on those points, as given by Lubbock, Prehistoric
Times, p. 354, &c.
Nor is the difference slight in moral disposition between a
barbarian, such as the man described by the old navigator Byron, who
dashed his child on the rocks for dropping a basket of sea-urchins,
and a Howard or Clarkson; and in intellect, between a savage who
uses hardly any abstract terms, and a Newton or Shakespeare.
Differences of this kind between the highest men of the highest
races and the lowest savages, are connected by the finest
gradations. Therefore it is possible that they might pass and be
developed into each other.
My object in this chapter is to shew that there is no fundamental
difference between man and the higher mammals in their mental
faculties. Each division of the subject might have been extended
into a separate essay, but must here be treated briefly. As no
classification of the mental powers has been universally accepted, I
shall arrange my remarks in the order most convenient for my
purpose; and will select those facts which have struck me most, with
the hope that they may produce some effect on the reader.
With respect to animals very low in the scale, I shall give some
additional facts under Sexual Selection, shewing that their mental
powers are much higher than might have been expected. The
variability of the faculties in the individuals of the same species is
an important point for us, and some few illustrations will here be
given. But it would be superfluous to enter into many details on
this head, for I have found on frequent enquiry, that it is the
unanimous opinion of all those who have long attended to animals of
many kinds, including birds, that the individuals differ greatly in
every mental characteristic. In what manner the mental powers were
first developed in the lowest organisms, is as hopeless an enquiry
as how life itself first originated. These are problems for the
distant future, if they are ever to be solved by man.
As man possesses the same senses as the lower animals, his
fundamental intuitions must be the same. Man has also some few
instincts in common, as that of self-preservation, sexual love, the
love of the mother for her new-born offspring, the desire possessed by
the latter to suck, and so forth. But man, perhaps, has somewhat fewer
instincts than those possessed by the animals which come next to him
in the series. The orang in the Eastern islands, and the chimpanzee in
Africa, build platforms on which they sleep; and, as both species
follow the same habit, it might be argued that this was due to
instinct, but we cannot feel sure that it is not the result of both
animals having similar wants, and possessing similar powers of
reasoning. These apes, as we may assume, avoid the many poisonous
fruits of the tropics, and man has no such knowledge: but as our
domestic animals, when taken to foreign lands, and when first turned
out in the spring, often eat poisonous herbs, which they afterwards
avoid, we cannot feel sure that the apes do not learn from their own
experience or from that of their parents what fruits to select. It is,
however, certain, as we shall presently see, that apes have an
instinctive dread of serpents, and probably of other dangerous
animals.
The fewness and the comparative simplicity of the instincts in the
higher animals are remarkable in contrast with those of the lower
animals. Cuvier maintained that instinct and intelligence stand in
an inverse ratio to each other; and some have thought that the
intellectual faculties of the higher animals have been gradually
developed from their instincts. But Pouchet, in an interesting essay,*
has shewn that no such inverse ratio really exists. Those insects
which possess the most wonderful instincts are certainly the most
intelligent. In the vertebrate series, the least intelligent
members, namely fishes and amphibians, do not possess complex
instincts; and amongst mammals the animal most remarkable for its
instincts, namely the beaver, is highly intelligent, as will be
admitted by every one who has read Mr. Morgan's excellent work.*(2)
* "L'Instinct chez les insectes," Revue des Deux Mondes, Feb., 1870,
p. 690.
*(2) The American Beaver and His Works, 1868.
Although the first dawnings of intelligence, according to Mr.
Herbert Spencer,* have been developed through the multiplication and
coordination of reflex actions, and although many of the simpler
instincts graduate into reflex actions, and can hardly be
distinguished from them, as in the case of young animals sucking,
yet the more complex instincts seem to have originated independently
of intelligence. I am, however, very far from wishing to deny that
instinctive actions may lose their fixed and untaught character, and
be replaced by others performed by the aid of the free will. On the
other hand, some intelligent actions, after being performed during
several generations, become converted into instincts and are
inherited, as when birds on oceanic islands learn to avoid man.
These actions may then be said to be degraded in character, for they
are no longer performed through reason or from experience. But the
greater number of the more complex instincts appear to have been
gained in a wholly different manner, through the natural selection
of variations of simpler instinctive actions. Such variations appear
to arise from the same unknown causes acting on the cerebral
organisation, which induce slight variations or individual differences
in other parts of the body; and these variations, owing to our
ignorance, are often said to arise spontaneously. We can, I think,
come to no other conclusion with respect to the origin of the more
complex instincts, when we reflect on the marvellous instincts of
sterile worker-ants and bees, which leave no offspring to inherit
the effects of experience and of modified habits.
* The Principles of Psychology, 2nd ed., 1870, pp. 418-443.
Although, as we learn from the above-mentioned insects and the
beaver, a high degree of intelligence is certainly compatible with
complex instincts, and although actions, at first learnt voluntarily
can soon through habit be performed with the quickness and certainty
of a reflex action, yet it is not improbable that there is a certain
amount of interference between the development of free intelligence
and of instinct,- which latter implies some inherited modification
of the brain. Little is known about the functions of the brain, but we
can perceive that as the intellectual powers become highly
developed, the various parts of the brain must be connected by very
intricate channels of the freest intercommunication; and as a
consequence each separate part would perhaps tend to be less well
fitted to answer to particular sensations or associations in a
definite and inherited- that is instinctive- manner. There seems
even to exist some relation between a low degree of intelligence and a
strong tendency to the formation of fixed, though not inherited
habits; for as a sagacious physician remarked to me, persons who are
slightly imbecile tend to act in everything by routine or habit; and
they are rendered much happier if this is encouraged.
I have thought this digression worth giving, because we may easily
underrate the mental powers of the higher animals, and especially of
man, when we compare their actions founded on the memory of past
events, on foresight, reason, and imagination, with exactly similar
actions instinctively performed by the lower animals; in this latter
case the capacity of performing such actions has been gained, step
by step, through the variability of the mental organs and natural
selection, without any conscious intelligence on the part of the
animal during each successive generation. No doubt, as Mr. Wallace has
argued,* much of the intelligent work done by man is due to
imitation and not to reason; but there is this great difference
between his actions and many of those performed by the lower
animals, namely, that man cannot, on his first trial, make, for
instance, a stone hatchet or a canoe, through his power of
imitation. He has to learn his work by practice; a beaver, on the
other hand, can make its dam or canal, and a bird its nest, as well,
or nearly as well, and a spider its wonderful web, quite as
well,*(2) the first time it tries as when old and experienced.
* Contributions to the Theory of Natural Selection, 1870, p. 212.
*(2) For the evidence on this head, see Mr. J. Traherne
Moggridge's most interesting work, Harvesting Ants and Trap-Door
Spiders, 1873, pp. 126, 128.
To return to our immediate subject: the lower animals, like man,
manifestly feel pleasure and pain, happiness and misery. Happiness
is never better exhibited than by young animals, such as puppies,
kittens, lambs, &c., when playing together, like our own children.
Even insects play together, as has been described by that excellent
observer, P. Huber,* who saw ants chasing and pretending to bite
each other, like so many puppies.
* Recherches sur les Moeurs des Fourmis, 1810, p. 173.
The fact that the lower animals are excited by the same emotions
as ourselves is so well established, that it will not be necessary
to weary the reader by many details. Terror acts in the same manner on
them as on us, causing the muscles to tremble, the heart to palpitate,
the sphincters to be relaxed, and the hair to stand on end. Suspicion,
the offspring of fear, is eminently characteristic of most wild
animals. It is, I think, impossible to read the account given by Sir
E. Tennent, of the behaviour of the female elephants, used as
decoys, without admitting that they intentionally practise deceit, and
well know what they are about. Courage and timidity are extremely
variable qualities in the individuals of the same species, as is
plainly seen in our dogs. Some dogs and horses are ill-tempered, and
easily turn sulky; others are good-tempered; and these qualities are
certainly inherited. Every one knows how liable animals are to furious
rage, and how plainly they shew it. Many, and probably true, anecdotes
have been published on the long-delayed and artful revenge of
various animals. The accurate Rengger, and Brehm* state that the
American and African monkeys which they kept tame, certainly
revenged themselves. Sir Andrew Smith, a zoologist whose scrupulous
accuracy was known to many persons, told me the following story of
which he was himself an eye-witness; at the Cape of Good Hope an
officer had often plagued a certain baboon, and the animal, seeing him
approaching one Sunday for parade, poured water into a hole and
hastily made some thick mud, which he skilfully dashed over the
officer as he passed by, to the amusement of many bystanders. For long
afterwards the baboon rejoiced and triumphed whenever he saw his
victim.
* All the following statements, given on the authority of these
two naturalists, are taken from Rengger's Naturgesch. der
Saugethiere von Paraguay, 1830, ss. 41-57, and from Brehm's
Thierleben, B. i., ss. 10-87.
The love of a dog for his master is notorious; as an old writer
quaintly says,* "A dog is the only thing on this earth that luvs you
more than he luvs himself."
* Quoted by Dr. Lauder Lindsay, in his "Physiology of Mind in the
Lower Animals," Journal of Mental Science, April, 1871, p. 38.
In the agony of death a dog has been known to caress his master, and
every one has heard of the dog suffering under vivisection, who licked
the hand of the operator; this man, unless the operation was fully
justified by an increase of our knowledge, or unless he had a heart of
stone, must have felt remorse to the last hour of his life.
As Whewell* has well asked, "Who that reads the touching instances
of maternal affection, related so often of the women of all nations,
and of the females of all animals, can doubt that the principle of
action is the same in the two cases?" We see maternal affection
exhibited in the most trifling details; thus Rengger observed an
American monkey (a Cebus) carefully driving away the flies which
plagued her infant; and Duvaucel saw a Hylobates washing the faces
of her young ones in a stream. So intense is the grief of female
monkeys for the loss of their young, that it invariably caused the
death of certain kinds kept under confinement by Brehm in N. Africa.
Orphan monkeys were always adopted and carefully guarded by the
other monkeys, both males and females. One female baboon had so
capacious a heart that she not only adopted young monkeys of other
species, but stole young dogs and cats, which she continually
carried about. Her kindness, however, did not go so far as to share
her food with her adopted offspring, at which Brehm was surprised,
as his monkeys always divided everything quite fairly with their own
young ones. An adopted kitten scratched this affectionate baboon,
who certainly had a fine intellect, for she was much astonished at
being scratched, and immediately examined the kitten's feet, and
without more ado bit off the claws.*(2) In the Zoological Gardens, I
heard from the keeper that an old baboon (C. chacma) had adopted a
Rhesus monkey; but when a young drill and mandrill were placed in
the cage, she seemed to perceive that these monkeys, though distinct
species, were her nearer relatives, for she at once rejected the
Rhesus and adopted both of them. The young Rhesus, as I saw, was
greatly discontented at being thus rejected, and it would, like a
naughty child, annoy and attack the young drill and mandrill
whenever it could do so with safety; this conduct exciting great
indignation in the old baboon. Monkeys will also, according to
Brehm, defend their master when attacked by any one, as well as dogs
to whom they are attached, from the attacks of other dogs. But we here
trench on the subjects of sympathy and fidelity, to which I shall
recur. Some of Brehm's monkeys took much delight in teasing a
certain old dog whom they disliked, as well as other animals, in
various ingenious ways.
* Bridgewater Treatise, p. 263.
*(2) A critic, without any grounds (Quarterly Review, July, 1871, p.
72), disputes the possibility of this act as described by Brehm, for
the sake of discrediting my work. Therefore I tried, and found that
I could readily seize with my own teeth the sharp little claws of a
kitten nearly five weeks old.
Most of the more complex emotions are common to the higher animals
and ourselves. Every one has seen how jealous a dog is of his master's
affection, if lavished on any other creature; and I have observed
the same fact with monkeys. This shews that animals not only love, but
have desire to be loved. Animals manifestly feel emulation. They
love approbation or praise; and a dog carrying a basket for his master
exhibits in a high degree self-complacency or pride. There can, I
think, be no doubt that a dog feels shame, as distinct from fear,
and something very like modesty when begging too often for food. A
great dog scorns the snarling of a little dog, and this may be
called magnanimity. Several observers have stated that monkeys
certainly dislike being laughed at; and they sometimes invent
imaginary offences. In the Zoological Gardens I saw a baboon who
always got into a furious rage when his keeper took out a letter or
book and read it aloud to him; and his rage was so violent that, as
I witnessed on one occasion, he bit his own leg till the blood flowed.
Dogs shew what may be fairly called a sense of humour, as distinct
from mere play; if a bit of stick or other such object be thrown to
one, he will often carry it away for a short distance; and then
squatting down with it on the ground close before him, will wait until
his master comes quite close to take it away. The dog will then
seize it and rush away in triumph, repeating the same manoeuvre, and
evidently enjoying the practical joke.
We will now turn to the more intellectual emotions and faculties,
which are very important, as forming the basis for the development
of the higher mental powers. Animals manifestly enjoy excitement,
and suffer from ennui, as may be seen with dogs, and, according to
Rengger, with monkeys. All animals feel Wonder, and many exhibit
Curiosity. They sometimes suffer from this latter quality, as when the
hunter plays antics and thus attracts them; I have witnessed this with
deer, and so it is with the wary chamois, and with some kinds of
wild-ducks. Brehm gives a curious account of the instinctive dread,
which his monkeys exhibited, for snakes; but their curiosity was so
great that they could not desist from occasionally satiating their
horror in a most human fashion, by lifting up the lid of the box in
which the snakes were kept. I was so much surprised at this account,
that I took a stuffed and coiled-up snake into the monkey-house at the
Zoological Gardens, and the excitement thus caused was one of the most
curious spectacles which I ever beheld. Three species of Cercopithecus
were the most alarmed; they dashed about their cages, and uttered
sharp signal cries of danger, which were understood by the other
monkeys. A few young monkeys and one old Anubis baboon alone took no
notice of the snake. I then placed the stuffed specimen on the
ground in one of the larger compartments. After a time all the monkeys
collected round it in a large circle, and staring intently,
presented a most ludicrous appearance. They became extremely
nervous; so that when a wooden ball, with which they were familiar
as a plaything, was accidentally moved in the straw, under which it
was partly hidden, they all instantly started away. These monkeys
behaved very differently when a dead fish, a mouse,* a living
turtle, and other new objects were placed in their cages; for though
at first frightened, they soon approached, handled and examined
them. I then placed a live snake in a paper bag, with the mouth
loosely closed, in one of the larger compartments. One of the
monkeys immediately approached, cautiously opened the bag a little,
peeped in, and instantly dashed away. Then I witnessed what Brehm
has described, for monkey after monkey, with head raised high and
turned on one side, could not resist taking a momentary peep into
the upright bag, at the dreadful object lying quietly at the bottom.
It would almost appear as if monkeys had some notion of zoological
affinities, for those kept by Brehm exhibited a strange, though
mistaken, instinctive dread of innocent lizards and frogs. An orang,
also, has been known to be much alarmed at the first sight of a
turtle.*(2)
* I have given a short account of their behaviour on this occasion
in my Expression of the Emotions in Man and Animals, p. 43.
*(2) W. C. L. Martin, Natural History of Mammalia, 1841, p. 405.
The principle of Imitation is strong in man, and especially, as I
have myself observed, with savages. In certain morbid states of the
brain this tendency is exaggerated to an extraordinary degree: some
hemiplegic patients and others, at the commencement of inflammatory
softening of the brain, unconsciously imitate every word which is
uttered, whether in their own or in a foreign language, and every
gesture or action which is performed near them.* Desor*(2) has
remarked that no animal voluntarily imitates an action performed by
man, until in the ascending scale we come to monkeys, which are well
known to be ridiculous mockers. Animals, however, sometimes imitate
each other's actions: thus two species of wolves, which had been
reared by dogs, learned to bark, as does sometimes the jackal,*(3) but
whether this can be called voluntary imitation is another question.
Birds imitate the songs of their parents, and sometimes of other
birds; and parrots are notorious imitators of any sound which they
often hear. Dureau de la Malle gives an account*(4) of a dog reared by
a cat, who learnt to imitate the well-known action of a cat licking
her paws, and thus washing her ears and face; this was also
witnessed by the celebrated naturalist Audouin. I have received
several confirmatory accounts; in one of these, a dog had not been
suckled by a cat, but had been brought up with one, together with
kittens, and had thus acquired the above habit, which he ever
afterwards practised during his life of thirteen years. Dureau de la
Malle's dog likewise learnt from the kittens to play with a ball by
rolling it about with his fore paws, and springing on it. A
correspondent assures me that a cat in his house used to put her
paws into jugs of milk having too narrow a mouth for her head. A
kitten of this cat soon learned the same trick, and practised it
ever afterwards, whenever there was an opportunity.
* Dr. Bateman, On Aphasia, 1870, p. 110.
*(2) Quoted by Vogt, Memoire sur les Microcephales, 1867, p. 168.
*(3) The Variation of Animals and Plants under Domestication, vol.
i., p. 27.
*(4) Annales des Sciences Nat., (1st series), tom, xxii., p. 397.
The parents of many animals, trusting to the principle of
imitation in their young, and more especially to their instinctive
or inherited tendencies, may be said to educate them. We see this when
a cat brings a live mouse to her kittens; and Dureau de la Malle has
given a curious account (in the paper above quoted) of his
observations on hawks which taught their young dexterity, as well as
judgment of distances, by first dropping through the air dead mice and
sparrows, which the young generally failed to catch, and then bringing
them live birds and letting them loose.
Hardly any faculty is more important for the intellectual progress
of man than Attention. Animals clearly manifest this power, as when
a cat watches by a hole and prepares to spring on its prey. Wild
animals sometimes become so absorbed when thus engaged, that they
may be easily approached. Mr. Bartlett has given me a curious proof
how variable this faculty is in monkeys. A man who trains monkeys to
act in plays, used to purchase common kinds from the Zoological
Society at the price of five pounds for each; but he offered to give
double the price, if he might keep three or four of them for a few
days, in order to select one. When asked how he could possibly learn
so soon, whether a particular monkey would turn out a good actor, he
answered that it all depended on their power of attention. If when
he was talking and explaining anything to a monkey, its attention
was easily distracted, as by a fly on the wall or other trifling
object, the case was hopeless. If he tried by punishment to make an
inattentive monkey act, it turned sulky. On the other hand, a monkey
which carefully attended to him could always be trained.
It is almost superfluous to state that animals have excellent
Memories for persons and places. A baboon at the Cape of Good Hope, as
I have been informed by Sir Andrew Smith, recognised him with joy
after an absence of nine months. I had a dog who was savage and averse
to all strangers, and I purposely tried his memory after an absence of
five years and two days. I went near the stable where he lived, and
shouted to him in my old manner; he shewed no joy, but instantly
followed me out walking, and obeyed me, exactly as if I had parted
with him only half an hour before. A train of old associations,
dormant during five years, had thus been instantaneously awakened in
his mind. Even ants, as P. Huber* has clearly shewn, recognised
their fellow-ants belonging to the same community after a separation
of four months. Animals can certainly by some means judge of the
intervals of time between recurrent events.
* Les Moeurs des Fourmis, 1810, p. 150.
The Imagination is one of the highest prerogatives of man. By this
faculty he unites former images and ideas, independently of the
will, and thus creates brilliant and novel results. A poet, as Jean
Paul Richter remarks,* "who must reflect whether he shall make a
character say yes or no- to the devil with him; he is only a stupid
corpse." Dreaming gives us the best notion of this power; as Jean Paul
again says, "The dream is an involuntary art of poetry." The value
of the products of our imagination depends of course on the number,
accuracy, and clearness of our impressions, on our judgment and
taste in selecting or rejecting the involuntary combinations, and to a
certain extent on our power of voluntarily combining them. As dogs,
cats, horses, and probably all the higher animals, even birds*(2) have
vivid dreams, and this is shewn by their movements and the sounds
uttered, we must admit that they possess some power of imagination.
There must be something special, which causes dogs to howl in the
night, and especially during moonlight, in that remarkable and
melancholy manner called baying. All dogs do not do so; and, according
to Houzeau,*(3) they do not then look at the moon, but at some fixed
point near the horizon. Houzeau thinks that their imaginations are
disturbed by the vague outlines of the surrounding objects, and
conjure up before them fantastic images: if this be so, their feelings
may almost be called superstitious.
* Quoted in Dr. Maudsley's Physiology and Pathology of Mind, 1868,
pp. 19, 220.
*(2) Dr. Jerdon, Birds of India, vol. i., 1862, p. xxi. Houzeau says
that his parakeets and canary-birds dreamt: Etudes sur les Facultes
Mentales des Animaux, tom. ii., p. 136.
*(3) ibid., 1872, tom. ii., p. 181.
Of all the faculties of the human mind, it will, I presume, be
admitted that Reason stands at the summit. Only a few persons now
dispute that animals possess some power of reasoning. Animals may
constantly be seen to pause, deliberate, and resolve. It is a
significant fact, that the more the habits of any particular animal
are studied by a naturalist, the more he attributes to reason and
the less to unlearnt instincts.* In future chapters we shall see
that some animals extremely low in the scale apparently display a
certain amount of reason. No doubt it is often difficult to
distinguish between the power of reason and that of instinct. For
instance. Dr. Hayes, in his work on The Open Polar Sea, repeatedly
remarks that his dogs, instead of continuing to draw the sledges in
a compact body, diverged and separated when they came to thin ice,
so that their weight might be more evenly distributed. This was
often the first warning which the travellers received that the ice was
becoming thin and dangerous. Now, did the dogs act thus from the
experience of each individual, or from the example of the older and
wiser dogs, or from an inherited habit, that is from instinct? This
instinct, may possibly have arisen since the time, long ago, when dogs
were first employed by the natives in drawing their sledges; or the
arctic wolves, the parent-stock of the Esquimaux dog, may have
acquired an instinct impelling them not to attack their prey in a
close pack, when on thin ice.
* Mr. L. H. Morgan's work on The American Beaver, 1868, offers a
good illustration of this remark. I cannot help thinking, however,
that he goes too far in undertaking the power of instinct.
We can only judge by the circumstances under which actions are
performed, whether they are due to instinct, or to reason, or to the
mere association of ideas: this latter principle, however, is
intimately connected with reason. A curious case has been given by
Prof. Mobius,* of a pike, separated by a plate of glass from an
adjoining aquarium stocked with fish, and who often dashed himself
with such violence against the glass in trying to catch the other
fishes, that he was sometimes completely stunned. The pike went on
thus for three months, but at last learnt caution, and ceased to do
so. The plate of glass was then removed, but the pike would not attack
these particular fishes, though he would devour others which were
afterwards introduced; so strongly was the idea of a violent shock
associated in his feeble mind with the attempt on his former
neighbours. If a savage, who had never seen a large plate-glass
window, were to dash himself even once against it, he would for a long
time afterwards associate a shock with a window-frame; but very
differently from the pike, he would probably reflect on the nature
of the impediment, and be cautious under analogous circumstances.
Now with monkeys, as we shall presently see, a painful or merely a
disagreeable impression, from an action once performed, is sometimes
sufficient to prevent the animal from repeating it. If we attribute
this difference between the monkey and the pike solely to the
association of ideas being so much stronger and more persistent in the
one than the other, though the pike often received much the more
severe injury, can we maintain in the case of man that a similar
difference implies the possession of a fundamentally different mind?
* Die Bewegungen der Thiere, &c., 1873, p. 11.
Houzeau relates* that, whilst crossing a wide and arid plain in
Texas, his two dogs suffered greatly from thirst, and that between
thirty and forty times they rushed down the hollows to search for
water. These hollows were not valleys, and there were no trees in
them, or any other difference in the vegetation, and as they were
absolutely dry there could have been no smell of damp earth. The
dogs behaved as if they knew that a dip in the ground offered them the
best chance of finding water, and Houzeau has often witnessed the same
behaviour in other animals.
* Etudes sur les Facultes Mentales des Animaux, 1872, tom. ii., p.
265.
I have seen, as I daresay have others, that when a small object is
thrown on the ground beyond the reach of one of the elephants in the
Zoological Gardens, he blows through his trunk on the ground beyond
the object, so that the current reflected on all sides may drive the
object within his reach. Again a well-known ethnologist, Mr. Westropp,
informs me that he observed in Vienna a bear deliberately making
with his paw a current in some water, which was close to the bars of
his cage, so as to draw a piece of floating bread within his reach.
These actions of the elephant and bear can hardly be attributed to
ins7tinct or inherited habit, as they would be of little use to an
animal in a state of nature. Now, what is the difference between
such actions, when performed by an uncultivated man, and by one of the
higher animals?
The savage and the dog have often found water at a low level, and
the coincidence under such circumstances has become associated in
their minds. A cultivated man would perhaps make some general
proposition on the subject; but from all that we know of savages it is
extremely doubtful whether they would do so, and a dog certainly would
not. But a savage, as well as a dog, would search in the same way,
though frequently disappointed; and in both it seems to be equally
an act of reason, whether or not any general proposition on the
subject is consciously placed before the mind.* The same would apply
to the elephant and the bear making currents in the air or water.
The savage would certainly neither know nor care by what law the
desired movements were effected; yet his act would be guided by a rude
process of reasoning, as surely as would a philosopher in his
longest chain of deductions. There would no doubt be this difference
between him and one of the higher animals, that he would take notice
of much slighter circumstances and conditions, and would observe any
connection between them after much less experience, and this would
be of paramount importance. I kept a daily record of the actions of
one of my infants, and when he was about eleven months old, and before
he could speak a single word, I was continually struck with the
greater quickness, with which all sorts of objects and sounds were
associated together in his mind, compared with that of the most
intelligent dogs I ever knew. But the higher animals differ in exactly
the same way in this power of association from those low in the scale,
such as the pike, as well as in that of drawing inferences and of
observation.
* Prof. Huxley has analysed with admirable clearness the mental
steps by which a man, as well as a dog, arrives at a conclusion in a
case analogous to that given in my text. See his article, "Mr.
Darwin's Critics," in the Contemporary Review, Nov., 1871, p. 462, and
in his Critiques and Essays, 1873, p. 279.
The promptings of reason, after very short experience, are well
shewn by the following actions of American monkeys, which stand low in
their order. Rengger, a most careful observer, states that when he
first gave eggs to his monkeys in Paraguay, they smashed them, and
thus lost much of their contents; afterwards they gently hit one end
against some hard body, and picked off the bits of shell with their
fingers. After cutting themselves only once with any sharp tool,
they would not touch it again, or would handle it with the greatest
caution. Lumps of sugar were often given them wrapped up in paper; and
Rengger sometimes put a live wasp in the paper, so that in hastily
unfolding it they got stung; after this had once happened, they always
first held the packet to their ears to detect any movement within.*
* Mr. Belt, in his most interesting work, The Naturalist in
Nicaragua, 1874, p. 119, likewise describes various actions of a tamed
Cebus, which, I think, clearly shew that this animal possessed some
reasoning power.
The following cases relate to dogs. Mr. Colquhoun* winged two
wild-ducks, which fell on the further side of a stream; his
retriever tried to bring over both at once, but could not succeed; she
then, though never before known to ruffle a feather, deliberately
killed one, brought over the other, and returned for the dead bird.
Col. Hutchinson relates that two partridges were shot at once, one
being killed, the other wounded; the latter ran away, and was caught
by the retriever, who on her return came across the dead bird; "she
stopped, evidently greatly puzzled, and after one or two trials,
finding she could not take it up without permitting the escape of
the winged bird, she considered a moment, then deliberately murdered
it by giving it a severe crunch, and afterwards brought away both
together. This was the only known instance of her ever having wilfully
injured any game." Here we have reason though not quite perfect, for
the retriever might have brought the wounded bird first and then
returned for the dead one, as in the case of the two wild-ducks. I
give the above cases, as resting on the evidence of two independent
witnesses, and because in both instances the retrievers, after
deliberation, broke through a habit which is inherited by them (that
of not killing the game retrieved), and because they shew how strong
their reasoning faculty must have been to overcome a fixed habit.
* The Moor and the Loch, p. 45. Col. Hutchinson on Dog Breaking,
1850, p. 46.
I will conclude by quoting a remark by the illustrious Humboldt.*
"The muleteers in S. America say, 'I will not give you the mule
whose step is easiest, but la mas racional,- the one that reasons
best'"; and; as, he adds, "this popular expression, dictated by long
experience, combats the system of animated machines, better perhaps
than all the arguments of speculative philosophy." Nevertheless some
writers even yet deny that the higher animals possess a trace of
reason; and they endeavor to explain away, by what appears to be
mere verbiage,*(2) all such facts as those above given.
* Personal Narrative, Eng. translat., vol. iii., p. 106.
*(2) I am glad to find that so acute a reasoner as Mr. Leslie
Stephen ("Darwinism and Divinity," Essays on Free Thinking, 1873, p.
80), in speaking of the supposed impassable barrier between the
minds of man and the lower animals, says, "The distinctions, indeed,
which have been drawn, seem to us to rest upon no better foundation
than a great many other metaphysical distinctions; that is, the
assumption that because you can give two things different names,
they must therefore have different natures. It is difficult to
understand how anybody who has ever kept a dog, or seen an elephant,
can have any doubt as to an animal's power of performing the essential
processes of reasoning."
It has, I think, now been shewn that man and the higher animals,
especially the primates, have some few instincts in common. All have
the same senses, intuitions, and sensations,- similar passions,
affections, and emotions, even the more complex ones, such as
jealousy, suspicion, emulation, gratitude, and magnanimity; they
practise deceit and are revengeful; they are sometimes susceptible
to ridicule, and even have a sense of humour; they feel wonder and
curiosity; they possess the same faculties of imitation, attention,
deliberation, choice, memory, imagination, the association of ideas,
and reason, though in very different degrees. The individuals of the
same species graduate in intellect from absolute imbecility to high
excellence. They are also liable to insanity, though far less often
than in the case of man.* Nevertheless, many authors have insisted
that man is divided by an insuperable barrier from all the lower
animals in in his mental faculties. I formerly made a collection of
above a score of such aphorisms, but they are almost worthless, as
their wide difference and number prove the difficulty, if not the
impossibility, of the attempt. It has been asserted that man alone
is capable of progressive improvement; that he alone makes use of
tools or fire, domesticates other animals, or possesses property; that
no animal has the power of abstraction, or of forming general
concepts, is self-conscious and comprehends itself; that no animal
employs language; that man alone has a sense of beauty, is liable to
caprice, has the feeling of gratitude, mystery, &c.; believes in
God, or is endowed with a conscience. I will hazard a few remarks on
the more important and interesting of these points.
* See "Madness in Animals," by Dr. W. Lauder Lindsay, in Journal
of Mental Science, July, 1871.
Archbishop Sumner formerly maintained* that man alone is capable
of progressive improvement. That he is capable of incomparably greater
and more rapid improvement than is any other animal, admits of no
dispute; and this is mainly due to his power of speaking and handing
down his acquired knowledge. With animals, looking first to the
individual, every one who has had any experience in setting traps,
knows that young animals can he caught much more easily than old ones;
and they can be much more easily approached by an enemy. Even with
respect to old animals, it is impossible to catch many in the same
place and in the same kind of trap, or to destroy them by the same
kind of poison; yet it is improbable that all should have partaken
of the poison, and impossible that all should have been caught in a
trap. They must learn caution by seeing their brethren caught or
poisoned. In North America, where the fur-bearing animals have long
been pursued, they exhibit, according to the unanimous testimony of
all observers, an almost incredible amount of sagacity, caution and
cunning; but trapping has been there so long carried on, that
inheritance may possibly have come into play. I have received
several accounts that when telegraphs are first set up in any
district, many birds kill themselves by flying against the wires,
but that in the course of a very few years they learn to avoid this
danger, by seeing, as it would appear, their comrades killed.*(2)
* Quoted by Sir C. Lyell, Antiquity of Man, p. 497.
*(2) For additional evidence, with details, see M. Houzeau, Etudes
sur les Facultes Mentales des Animaux, tom. ii., 1872, p. 147.
If we look to successive generations, or to the race, there is no
doubt that birds and other animals gradually both acquire and lose
caution in relation to man or other enemies;* and this caution is
certainly in chief part an inherited habit or instinct, but in part
the result of individual experience. A good observer, Leroy,*(2)
states, that in districts where foxes are much hunted, the young, on
first leaving their burrows, are incontestably much more wary than the
old ones in districts where they are not much disturbed.
* See, with respect to birds on oceanic islands, my Journal of
Researches during the Voyage of the "Beagle," 1845, p. 398. Also,
Origin of Species.(OOS)
*(2) Lettres Phil. sur l'Intelligence des Animaux, nouvelle edit.,
1802, p. 86.
Our domestic dogs are descended from wolves and jackals,* and though
they may not have gained in cunning, and may have lost in wariness and
suspicion, yet they have progressed in certain moral qualities, such
as in affection, trust-worthiness, temper, and probably in general
intelligence. The common rat has conquered and beaten several other
species throughout Europe, in parts of North America, New Zealand, and
recently in Formosa, as well as on the mainland of China. Mr.
Swinhoe,*(2) who describes these two latter cases, attributes the
victory of the common rat over the large Mus coninga to its superior
cunning; and this latter quality may probably be attributed to the
habitual exercise of all its faculties in avoiding extirpation by man,
as well as to nearly all the less cunning or weak-minded rats having
been continuously destroyed by him. It is, however, possible that
the success of the common rat may be due to its having possessed
greater cunning than its fellow-species, before it became associated
with man. To maintain, independently of any direct evidence, that no
animal during the course of ages has progressed in intellect or
other mental faculties, is to beg the question of the evolution of
species. We have seen that, according to Lartet, existing mammals
belonging to several orders have larger brains than their ancient
tertiary prototypes.
* See the evidence on this head in chap. i., vol. i., On the
Variation of Animals and Plants under Domestication.
*(2) Proceedings Zoological Society, 1864, p. 186.
It has often been said that no animal uses any tool; but the
chimpanzee in a state of nature cracks a native fruit, somewhat like a
walnut, with a stone.* Rengger*(2) easily taught an American monkey
thus to break open hard palm-nuts; and afterwards of its own accord,
it used stones to open other kinds of nuts, as well as boxes. It
thus also removed the soft rind of fruit that had a disagreeable
flavour. Another monkey was taught to open the lid of a large box with
a stick, and afterwards it used the stick as a lever to move heavy
bodies; and I have myself seen a young orang put a stick into a
crevice, slip his hand to the other end, and use it in the proper
manner as a lever. The tamed elephants in India are well known to
break off branches of trees and use them to drive away the flies;
and this same act has been observed in an elephant in a state of
nature.*(3) I have seen a young orang, when she thought she was
going to be whipped, cover and protect herself with a blanket or
straw. In these several cases stones and sticks were employed as
implements; but they are likewise used as weapons. Brehm*(4) states,
on the authority of the well-known traveller Schimper, that in
Abyssinia when the baboons belonging to one species (C. gelada)
descend in troops from the mountains to plunder the fields, they
sometimes encounter troops of another species (C. hamadryas), and then
a fight ensues. The Geladas roll down great stones, which the
Hamadryas try to avoid, and then both species, making a great
uproar, rush furiously against each other. Brehm, when accompanying
the Duke of Coburg-Gotha, aided in an attack with fire-arms on a troop
of baboons in the pass of Mensa in Abyssinia. The baboons in return
rolled so many stones down the mountain, some as large as a man's
head, that the attackers had to beat a hasty retreat; and the pass was
actually closed for a time against the caravan. It deserves notice
that these baboons thus acted in concert. Mr. Wallace*(5) on three
occasions saw female orangs, accompanied by their young, "breaking off
branches and the great spiny fruit of the Durian tree, with every
appearance of rage; causing such a shower of missiles as effectually
kept us from approaching too near the tree." As I have repeatedly
seen, a chimpanzee will throw any object at hand at a person who
offends him; and the before-mentioned baboon at the Cape of Good
Hope prepared mud for the purpose.
* Savage and Wyman in Boston Journal of Natural History, vol. iv.,
1843-44, p. 383.
*(2) Saugethiere von Paraguay, 1830, ss. 51-56.
*(3) The Indian Field, March 4, 1871.
*(4) Illustriertes Thierleben, B. i., s. 79, 82.
*(5) The Malay Archipelago, vol. i., 1869, p. 87.
In the Zoological Gardens, a monkey, which had weak teeth, used to
break open nuts with a stone; and I was assured by the keepers that
after using the stone, he hid it in the straw, and would not let any
other monkey touch it. Here, then, we have the idea of property; but
this idea is common to every dog with a bone, and to most or all birds
with their nests.
The Duke of Argyll* remarks, that the fashioning of an implement for
a special purpose is absolutely peculiar to man; and he considers that
this forms an immeasurable gulf between him and the brutes. This is no
doubt a very important distinction; but there appears to me much truth
in Sir J. Lubbock's suggestion,*(2) that when primeval man first
used flint-stones for any purpose, he would have accidentally
splintered them, and would then have used the sharp fragments. From
this step it would be a small one to break the flints on purpose,
and not a very wide step to fashion them rudely. This latter
advance, however, may have taken long ages, if we may judge by the
immense interval of time which elapsed before the men of the neolithic
period took to grinding and polishing their stone tools. In breaking
the flints, as Sir J. Lubbock likewise remarks, sparks would have been
emitted, and in grinding them heat would have been evolved: thus the
two usual methods of "obtaining fire may have originated." The
nature of fire would have been known in the many volcanic regions
where lava occasionally flows through forests. The anthropomorphous
apes, guided probably by instinct, build for themselves temporary
platforms; but as many instincts are largely controlled by reason, the
simpler ones, such as this of building a platform, might readily
pass into a voluntary and conscious act. The orang is known to cover
itself at night with the leaves of the pandanus; and Brehm states that
one of his baboons used to protect itself from the heat of the sun
by throwing a straw-mat over its head. In these several habits, we
probably see the first steps towards some of the simpler arts, such as
rude architecture and dress, as they arose amongst the early
progenitors of man.
* Primeval Man, 1869, pp. 145, 147.
*(2) Prehistoric Times, 1865, p. 473, &c.
Abstraction, General Conceptions, Self-consciousness, Mental
Individuality.- It would be very difficult for any one with even
much more knowledge than I possess, to determine how far animals
exhibit any traces of these high mental powers. This difficulty arises
from the impossibility of judging what passes through the mind of an
animal; and again, the fact that writers differ to a great extent in
the meaning which they attribute to the above terms, causes a
further difficulty. If one may judge from various articles which
have been published lately, the greatest stress seems to be laid on
the supposed entire absence in animals of the power of abstraction, or
of forming general concepts. But when a dog sees another dog at a
distance, it is often clear that he perceives that it is a dog in
the abstract; for when he gets nearer his whole manner suddenly
changes if the other dog be a friend. A recent writer remarks, that in
all such cases it is a pure assumption to assert that the mental act
is not essentially of the same nature in the animal as in man. If
either refers what he perceives with his senses to a mental concept,
then so do both.* When I say to my terrier, in an eager voice (and I
have made the trial many times), "Hi, hi, where is it?" she at once
takes it as a sign that something is to be hunted, and generally first
looks quickly all around, and then rushes into the nearest thicket, to
scent for any game, but finding nothing, she looks up into any
neighbouring tree for a squirrel. Now do not these actions clearly
shew that she had in her mind a general idea or concept that some
animal is to be discovered and hunted?
* Mr. Hookham, in a letter to Prof. Max Muller, in the Birmingham
News, May, 1873.
It may be freely admitted that no animal is self-conscious, if by
this term it is implied, that he reflects on such points, as whence he
comes or whither he will go, or what is life and death, and so
forth. But how can we feel sure that an old dog with an excellent
memory and some power of imagination, as shewn by his dreams, never
reflects on his past pleasures or pains in the chase? And this would
be a form of self-consciousness. On the other hand, as Buchner* has
remarked, how little can the hard worked wife of a degraded Australian
savage, who uses very few abstract words, and cannot count above four,
exert her self-consciousness, or reflect on the nature of her own
existence. It is generally admitted, that the higher animals possess
memory, attention, association, and even some imagination and
reason. If these powers, which differ much in different animals, are
capable of improvement, there seems no great improbability in more
complex faculties, such as the higher forms of abstraction, and
self-consciousness, &c., having been evolved through the development
and combination of the simpler ones. It has been urged against the
views here maintained that it is impossible to say at what point in
the ascending scale animals become capable of abstraction, &c.; but
who can say at what age this occurs in our young children? We see at
least that such powers are developed in children by imperceptible
degrees.
* Conferences sur la Theorie Darwinienne, French translat., 1869, p.
132.
That animals retain their mental individuality is unquestionable.
When my voice awakened a train of old associations in the mind of
the before-mentioned dog, he must have retained his mental
individuality, although every atom of his brain had probably undergone
change more than once during the interval of five years. This dog
might have brought forward the argument lately advanced to crush all
evolutionists, and said, "I abide amid all mental moods and all
material changes.... The teaching that atoms leave their impressions
as legacies to other atoms falling into the places they have vacated
is contradictory of the utterance of consciousness, and is therefore
false; but it is the teaching necessitated by evolutionism,
consequently the hypothesis is a false one."*
* The Rev. Dr. J. M'Cann, Anti-Darwinism, 1869, p. 13.
Language.- This faculty has justly been considered as one of the
chief distinctions between man and the lower animals. But man, as a
highly competent judge, Archbishop Whately remarks, "is not the only
animal that can make use of language to express what is passing in his
mind, and can understand, more or less, what is so expressed by
another."* In Paraguay the Cebus azarae when excited utters at least
six distinct sounds, which excite in other monkeys similar
emotions.*(2) The movements of the features and gestures of monkeys
are understood by us, and they partly understand ours, as Rengger
and others declare. It is a more remarkable fact that the dog, since
being domesticated, has learnt to bark*(3) in at least four or five
distinct tones. Although barking is a new art, no doubt the wild
parent-species of the dog expressed their feelings by cries of various
kinds. With the domesticated dog we have the bark of eagerness, as
in the chase; that of anger, as well as growling; the yelp or howl
of despair, as when shut up; the baying at night; the bark of joy,
as when starting on a walk with his master; and the very distinct
one of demand or supplication, as when wishing for a door or window to
be opened. According to Houzeau, who paid particular attention to
the subject, the domestic fowl utters at least a dozen significant
sounds.*(4)
* Quoted in Anthropological Review, 1864, p. 158.
*(2) Rengger, ibid., s. 45.
*(3) See my Variation of Animals and Plants under Domestication,
vol. i., p. 27.
*(4) Facultes Mentales des Animaux, tom. ii., 1872, p. 346-349.
The habitual use of articulate language is, however, peculiar to
man; but he uses, in common with the lower animals, inarticulate cries
to express his meaning, aided by gestures and the movements of the
muscles of the face.* This especially holds good with the more
simple and vivid feelings, which are but little connected with our
higher intelligence. Our cries of pain, fear, surprise, anger,
together with their appropriate actions, and the murmur of a mother to
her beloved child are more expressive than any words. That which
distinguishes man from the lower animals is not the understanding of
articulate sounds, for, as every one knows, dogs understand many words
and sentences. In this respect they are at the same stage of
development as infants, between the ages of ten and twelve months, who
understand many words and short sentences, but cannot yet utter a
single word. It is not the mere articulation which is our
distinguishing character, for parrots and other birds possess this
power. Nor is it the mere capacity of connecting definite sounds
with definite ideas; for it is certain that some parrots, which have
been taught to speak, connect unerringly words with things, and
persons with events.*(2) The lower animals differ from man solely in
his almost infinitely larger power of associating together the most
diversified sounds and ideas; and this obviously depends on the high
development of his mental powers.
* See a discussion on this subject in Mr. E. B. Tylor's very
interesting work, Researches into the Early History of Mankind,
1865, chaps. ii. to iv.
*(2) I have received several detailed accounts to this effect.
Admiral Sir. B. J. Sulivan, whom I know to be a careful observer,
assures me that an African parrot, long kept in his father's house,
invariably called certain persons of the household, as well as
visitors, by their names. He said "good morning" to every one at
breakfast, and "good night" to each as they left the room at night,
and never reversed these salutations. To Sir B. J. Sulivan's father,
he used to add to the " good morning" a short sentence, which was
never once repeated after his father's death. He scolded violently a
strange dog which came into the room through the open window; and he
scolded another parrot (saying "you naughty polly") which had got
out of its cage, and was eating apples on the kitchen table. See also,
to the same effect, Houzeau on parrots, Facultes Mentales, tom. ii.,
p. 309. Dr. A. Moschkau informs me that he knew a starling which never
made a mistake in saying in German " good morning" to persons
arriving, and "good bye, old fellow," to those departing. I could
add several other such cases.
As Horne Tooke, one of the founders of the noble science of
philology, observes, language is an art, like brewing or baking; but
writing would have been a better simile. It certainly is not a true
instinct, for every language has to be learnt. It differs, however,
widely from all ordinary arts, for man has an instinctive tendency
to speak, as we see in the babble of our young children; whilst no
child has an instinctive tendency to brew, bake, or write. Moreover,
no philologist now supposes that any language has been deliberately
invented; it has been slowly and unconsciously developed by many
steps.* The sounds uttered by birds offer in several respects the
nearest analogy to language, for all the members of the same species
utter the same instinctive cries expressive of their emotions; and all
the kinds which sing, exert their power instinctively; but the
actual song, and even the call-notes, are learnt from their parents or
foster-parents. These sounds, as Daines Barrington*(2) has proved,
"are no more innate than language is in man." The first attempts to
sing "may be compared to the imperfect endeavour in a child to
babble." The young males continue practising, or as the
bird-catchers say, "recording," for ten or eleven months. Their
first essays show hardly a rudiment of the future song; but as they
grow older we can perceive what they are aiming at; and at last they
are said "to sing their song round." Nestlings which have learnt the
song of a distinct species, as with the canary-birds educated in the
Tyrol, teach and transmit their new song to their offspring. The
slight natural differences of song in the same species inhabiting
different districts may be appositely compared, as Barrington remarks,
"to provincial dialects"; and the songs of allied, though distinct
species may be compared with the languages of distinct races of man. I
have given the foregoing details to shew that an instinctive
tendency to acquire an art is not peculiar to man.
* See some good remarks on this head by Prof. Whitney, in his
Oriental and Linguistic Studies, 1873, p. 354. He observes that the
desire of communication between man is the living force, which, in the
development of language, "works both consciously and unconsciously;
consciously as regards the immediate end to be attained; unconsciously
as regards the further consequences of the act."
*(2) Hon. Daines Barrington in Philosoph. Transactions, 1773, p.
262. See also Dureau de la Malle, in Ann. des. Sc. Nat., 3rd series,
Zoolog., tom. x., p. 119.
With respect to the origin of articulate language, after having read
on the one side the highly interesting works of Mr. Hensleigh
Wedgwood, the Rev. F. Farrar, and Prof. Schleicher,* and the
celebrated lectures of Prof. Max Muller on the other side, I cannot
doubt that language owes its origin to the imitation and
modification of various natural sounds, the voices of other animals,
and man's own instinctive cries, aided by signs and gestures. When
we treat of sexual selection we shall see that primeval man, or rather
some early progenitor of man, probably first used his voice in
producing true musical cadences, that is in singing, as do some of the
gibbon-apes at the present day; and we may conclude from a
widely-spread analogy, that this power would have been especially
exerted during the courtship of the sexes,- would have expressed
various emotions, such as love, jealousy, triumph,- and would have
served as a challenge to rivals. It is, therefore, probable that the
imitation of musical cries by articulate sounds may have given rise to
words expressive of various complex emotions. The strong tendency in
our nearest allies, the monkeys, in microcephalous idiots,*(2) and
in the barbarous races of mankind, to imitate whatever they hear
deserves notice, as bearing on the subject of imitation. Since monkeys
certainly understand much that is said to them by man, and when
wild, utter signal-cries of danger to their fellows;*(3) and since
fowls give distinct warnings for danger on the ground, or in the sky
from hawks (both, as well as a third cry, intelligible to dogs),*(4)
may not some unusually wise apelike animal have imitated the growl
of a beast of prey, and thus told his fellow-monkeys the nature of the
expected danger? This would have been a first step in the formation of
a language.
* On the Origin of Language, by H. Wedgwood, 1866. Chapters on
Language, by the Rev. F. W. Farrar, 1865. These works are most
interesting. See also De la Phys. et de Parole, par Albert Lemoine,
1865, p. 190. The work on this subject, by the late Prof. Aug.
Schleicher, has been translated by Dr. Bikkers into English, under the
title of Darwinism tested by the Science of Language, 1869.
*(2) Vogt, Memoire sur les Microcephales, 1867, p. 169. With respect
to savages, I have given some facts in my Journal of Researches,
&c., 1845, p. 206.
*(3) See clear evidence on this head in the two works so often
quoted, by Brehm and Rengger.
*(4) Houzeau gives a very curious account of his observations on
this subject in his Facultes Mentales des Animaux, tom. ii., p. 348.
As the voice was used more and more, the vocal organs would have
been strengthened and perfected through the principle of the inherited
effects of use; and this would have reacted on the power of speech.
But the relation between the continued use of language and the
development of the brain, has no doubt been far more important. The
mental powers in some early progenitor of man must have been more
highly developed than in any existing ape, before even the most
imperfect form of speech could have come into use; but we may
confidently believe that the continued use and advancement of this
power would have reacted on the mind itself, by enabling and
encouraging it to carry on long trains of thought. A complex train
of thought can no more be carried on without the aid of words, whether
spoken or silent, than a long calculation without the use of figures
or algebra. It appears, also, that even an ordinary train of thought
almost requires, or is greatly facilitated by some form of language,
for the dumb, deaf, and blind girl, Laura Bridgman, was observed to
use her fingers whilst dreaming.* Nevertheless, a long succession of
vivid and connected ideas may pass through the mind without the aid of
any form of language, as we may infer from the movements of dogs
during their dreams. We have, also, seen that animals are able to
reason to a certain extent, manifestly without the aid of language.
The intimate connection between the brain, as it is now developed in
us, and the faculty of speech, is well shewn by those curious cases of
brain-disease in which speech is specially affected, as when the power
to remember substantives is lost, whilst other words can be
correctly used, or where substantives of a certain class, or all
except the initial letters of substantives and proper names are
forgotten.*(2) There is no more improbability in the continued use
of the mental and vocal organs leading to inherited changes in their
structure and functions, than in the case of hand-writing, which
depends partly on the form of the hand and partly on the disposition
of the mind; and handwriting is certainly inherited.*(3)
* See remarks on this head by Dr. Maudsley, The Physiology and
Pathology of Mind, 2nd ed., 1868, p. 199.
*(2) Many curious cases have been recorded. See, for instance, Dr.
Bateman On Aphasia, 1870, pp. 27, 31, 53, 100, &c. Also, Inquiries
Concerning the Intellectual Powers, by Dr. Abercrombie, 1838, p. 150.
*(3) The Variation of Animals and Plants under Domestication, vol.
ii., p. 6.
Several writers, more especially Prof. Max Muller,* have lately
insisted that the use of language implies the power of forming general
concepts; and that as no animals are supposed to possess this power,
an impassable barrier is formed between them and man.*(2) With respect
to animals, I have already endeavoured to shew that they have this
power, at least in a rude and incipient degree. As far as concerns
infants of from ten to eleven months old, and deaf-mutes, it seems
to me incredible, that they should be able to connect certain sounds
with certain general ideas as quickly as they do, unless such ideas
were already formed in their minds. The same remark may be extended to
the more intelligent animals; as Mr. Leslie Stephen observes,*(3) "A
dog frames a general concept of cats or sheep, and knows the
corresponding words as well as a philosopher. And the capacity to
understand is as good a proof of vocal intelligence, though in an
inferior degree, as the capacity to speak."
* Lectures on Mr. Darwin's Philosophy of Language, 1873.
*(2) The judgment of a distinguished philologist, such as Prof.
Whitney, will have far more weight on this point than anything that
I can say. He remarks (Oriental and Linguistic Studies, 1873, p. 297),
in speaking of Bleek's views: "Because on the grand scale language
is the necessary auxiliary of thought, indispensable to the
development of the power of thinking, to the distinctness and
variety and complexity of cognitions, to the full mastery of
consciousness; therefore he would fain make thought absolutely
impossible without speech, identifying the faculty with its
instrument. He might just as reasonably assert that the human hand
cannot act without a tool. With such a doctrine to start from, he
cannot stop short of Max Muller's worst paradoxes, that an infant
(in fans, not speaking) is not a human being, and that deaf-mutes do
not become possessed of reason until they learn to twist their fingers
into imitation of spoken words." Max Muller gives in italics (Lectures
on Mr. Darwin's Philosophy of Language, 1873, third lecture) this
aphorism: "There is no thought without words, as little as there are
words without thought." What a strange definition must here be given
to the word thought!
*(3) Essays on Free Thinking, &c., 1873, p. 82.
Why the organs now used for speech should have been originally
perfected for this purpose, rather than any other organs, it is not
difficult to see. Ants have considerable powers of inter-communication
by means of their antennae, as shewn by Huber, who devotes a whole
chapter to their language. We might have used our fingers as efficient
instruments, for a person with practice can report to a deaf man every
word of a speech rapidly delivered at a public meeting; but the loss
of our hands, whilst thus employed, would have been a serious
inconvenience. As all the higher mammals possess vocal organs,
constructed on the same general plan as ours, and used as a means of
communication, it was obviously probable that these same organs
would be still further developed if the power of communication had
to be improved; and this has been effected by the aid of adjoining and
well adapted parts, namely the tongue and lips.* The fact of the
higher apes not using their vocal organs for speech, no doubt
depends on their intelligence not having been sufficiently advanced.
The possession by them of organs, which with long-continued practice
might have been used for speech, although not thus used, is paralleled
by the case of many birds which possess organs fitted for singing,
though they never sing. Thus, the nightingale and crow have vocal
organs similarly constructed, these being used by the former for
diversified song, and by the latter only for croaking.*(2) If it be
asked why apes have not had their intellects developed to the same
degree as that of man, general causes only can be assigned in
answer, and it is unreasonable to expect any thing more definite,
considering our ignorance with respect to the successive stages of
development through which each creature has passed.
* See some good remarks to this effect by Dr. Maudsley, The
Physiology and Pathology of Mind, 1868, p. 199.
*(2) Macgillivray, Hist. of British Birds, vol. ii., 1839, p. 29. An
excellent observer, Mr. Blackwall remarks that the magpie learns to
pronounce single words, and even short sentences, more readily than
almost any other British bird; yet, as he adds, after long and closely
investigating its habits, he has never known it, in a state of nature,
display any unusual capacity for imitation. Researches in Zoology,
1834, p. 158.
The formation of different languages and of distinct species, and
the proofs that both have been developed through a gradual process,
are curiously parallel.* But we can trace the formation of many
words further back than that of species, for we can perceive how
they actually arose from the imitation of various sounds. We find in
distinct languages striking homologies due to community of descent,
and analogies due to a similar process of formation. The manner in
which certain letters or sounds change when others change is very like
correlated growth. We have in both cases the re-duplication of
parts, the effects of long-continued use, and so forth. The frequent
presence of rudiments, both in languages and in species, is still more
remarkable. The letter m in the word am, means I; so that in the
expression I am, a superfluous and useless rudiment has been retained.
In the spelling also of words, letters often remain as the rudiments
of ancient forms of pronunciation. Languages, like organic beings, can
be classed in groups under groups; and they can be classed either
naturally according to descent, or artificially by other characters.
Dominant languages and dialects spread widely, and lead to the gradual
extinction of other tongues. A language, like a species, when once
extinct, never, as Sir C. Lyell remarks, reappears. The same
language never has two birth-places. Distinct languages may be crossed
or blended together.*(2) We see variability in every tongue, and new
words are continually cropping up; but as there is a limit to the
powers of the memory, single words, like whole languages, gradually
become extinct. As Max Muller*(3) has well remarked:- "A struggle
for life is constantly going on amongst the words and grammatical
forms in each language. The better, the shorter, the easier forms
are constantly gaining the upper hand, and they owe their success to
their own inherent virtue." To these more important causes of the
survival of certain words, mere novelty and fashion may be added;
for there is in the mind of man a strong love for slight changes in
all things. The survival or preservation of certain favoured words
in the struggle for existence is natural selection.
* See the very interesting parallelism between the development of
species and languages, given by Sir C. Lyell in The Geological
Evidences of the Antiquity of Man, 1863, chap. xxiii.
*(2) See remarks to this effect by the Rev. F. W. Farrar, in an
interesting article, entitled Philology and Darwinism," in Nature,
March 24, 1870, p. 528.
*(3) Nature, January 6, 1870, p. 257.
The perfectly regular and wonderfully complex construction of the
languages of many barbarous nations has often been advanced as a
proof, either of the divine origin of these languages, or of the
high art and former civilisation of their founders. Thus F. von
Schlegel writes: "In those languages which appear to be at the
lowest grade of intellectual culture, we frequently observe a very
high and elaborate degree of art in their grammatical structure.
This is especially the case with the Basque and the Lapponian, and
many of the American languages."* But it is assuredly an error to
speak of any language as an art, in the sense of its having been
elaborately and methodically formed. Philologists now admit that
conjugations, declensions, &c., originally existed as distinct
words, since joined together; and as such words express the most
obvious relations between objects and persons, it is not surprising
that they should have been used by the men of most races during the
earliest ages. With respect to perfection, the following
illustration will best shew how easily we may err: a crinoid sometimes
consists of no less than 150,000 pieces of shell,*(2) all arranged
with perfect symmetry in radiating lines; but a naturalist does not
consider an animal of this kind as more perfect than a bilateral one
with comparatively few parts, and with none of these parts alike,
excepting on the opposite sides of the body. He justly considers the
differentiation and specialisation of organs as the test of
perfection. So with languages: the most symmetrical and complex
ought not to be ranked above irregular, abbreviated, and bastardised
languages, which have borrowed expressive words and useful forms of
construction from various conquering, conquered, or immigrant races.
* Quoted by C. S. Wake, Chapters on Man, 1868, p. 101.
*(2) Buckland, Bridgewater Treatise, p. 411.
From these few and imperfect remarks I conclude that the extremely
complex and regular construction of many barbarous languages, is no
proof that they owe their origin to a special act of creation.* Nor,
as we have seen, does the faculty of articulate speech in itself offer
any insuperable objection to the belief that man has been developed
from some lower form.
* See some good remarks on the simplification of languages, by Sir
J. Lubbock, Origin of Civilisation, 1870, p. 278.
Sense of Beauty.- This sense has been declared to be peculiar to
man. I refer here only to the pleasure given by certain colours,
forms, and sounds, and which may fairly be called a sense of the
beautiful; with cultivated men such sensations are, however,
intimately associated with complex ideas and trains of thought. When
we behold a male bird elaborately displaying his graceful plumes or
splendid colours before the female, whilst other birds, not thus
decorated, make no such display, it is impossible to doubt that she
admires the beauty of her male partner. As women everywhere deck
themselves with these plumes, the beauty of such ornaments cannot be
disputed. As we shall see later, the nests of humming-birds, and the
playing passages of bower-birds are tastefully ornamented with
gaily-coloured objects; and this shews that they must receive some
kind of pleasure from the sight of such things. With the great
majority of animals, however, the taste for the beautiful is confined,
as far as we can judge, to the attractions of the opposite sex. The
sweet strains poured forth by many male birds during the season of
love, are certainly admired by the females, of which fact evidence
will hereafter be given. If female birds had been incapable of
appreciating the beautiful colours, the ornaments, and voices of their
male partners, all the labour and anxiety exhibited by the latter in
displaying their charms before the females would have been thrown
away; and this it is impossible to admit. Why certain bright colours
should excite pleasure cannot, I presume, be explained, any more
than why certain flavours and scents are agreeable; but habit has
something to do with the result, for that which is at first unpleasant
to our senses, ultimately becomes pleasant, and habits are
inherited. With respect to sounds, Helmholtz has explained to a
certain extent on physiological principles, why harmonies and
certain cadences are agreeable. But besides this, sounds frequently
recurring at irregular intervals are highly disagreeable, as every one
will admit who has listened at night to the irregular flapping of a
rope on board ship. The same principle seems to come into play with
vision, as the eye prefers symmetry or figures with some regular
recurrence. Patterns of this kind are employed by even the lowest
savages as ornaments; and they have been developed through sexual
selection for the adornment of some male animals. Whether we can or
not give any reason for the pleasure thus derived from vision and
hearing, yet man and many of the lower animals are alike pleased by
the same colours, graceful shading and forms, and the same sounds.
The taste for the beautiful, at least as far as female beauty is
concerned, is not of a special nature in the human mind; for it
differs widely in the different races of man, and is not quite the
same even in the different nations of the same race. Judging from
the hideous ornaments, and the equally hideous music admired by most
savages, it might be urged that their Aesthetic faculty was not so
highly developed as in certain animals, for instance, as in birds.
Obviously no animal would be capable of admiring such scenes as the
heavens at night, a beautiful landscape, or refined music; but such
high tastes are acquired through culture, and depend on complex
associations; they are not enjoyed by barbarians or by uneducated
persons.
Many of the faculties, which have been of inestimable service to man
for his progressive advancement, such as the powers of the
imagination, wonder, curiosity, an undefined sense of beauty, a
tendency to imitation, and the love of excitement or novelty, could
hardly fail to lead to capricious changes of customs and fashions. I
have alluded to this point, because a recent writer* has oddly fixed
on Caprice "as one of the most remarkable and typical differences
between savages and brutes." But not only can we partially
understand how it is that man is from various conflicting influences
rendered capricious, but that the lower animals are, as we shall
hereafter see, likewise capricious in their affections, aversions, and
sense of beauty. There is also reason to suspect that they love
novelty, for its own sake.
* The Spectator, Dec. 4. 1869, p. 1430.
Belief in God- Religion.- There is no evidence that man was
aboriginally endowed with the ennobling belief in the existence of
an Omnipotent God. On the contrary there is ample evidence, derived
not from hasty travellers, but from men who have long resided with
savages, that numerous races have existed, and still exist, who have
no idea of one or more gods, and who have no words in their
languages to express such an idea.* The question is of course wholly
distinct from that higher one, whether there exists a Creator and
Ruler of the universe; and this has been answered in the affirmative
by some of the highest intellects that have ever existed.
* See an excellent article on this subject by the Rev. F. W. Farrar,
in the Anthropological Review, Aug., 1864, p. ccxvii. For further
facts see Sir J. Lubbock, Prehistoric Times, 2nd ed., 1869, p. 564;
and especially the chapters on Religion in his Origin of Civilisation,
1870.
If, however, we include under the term "religion" the belief in
unseen or spiritual agencies the case is wholly different; for this
belief seems to be universal with the less civilised races. Nor is
it difficult to comprehend how it arose. As soon as the important
faculties of the imagination, wonder, and curiosity, together with
some power of reasoning, had become partially developed, man would
naturally crave to understand what was passing around him, and would
have vaguely speculated on his own existence. As Mr. M'Lennan* has
remarked, "Some explanation of the phenomena of life, a man must feign
for himself, and to judge from the universality of it, the simplest
hypothesis, and the first to occur to men, seems to have been that
natural phenomena are ascribable to the presence in animals, plants,
and things, and in the forces of nature, of such spirits prompting
to action as men are conscious they themselves possess." It is also
probable, as Mr. Tylor has shewn, that dreams may have first given
rise to the notion of spirits; for savages do not readily
distinguish between subjective and objective impressions. When a
savage dreams, the figures which appear before him are believed to
have come from a distance, and to stand over him; or "the soul of
the dreamer goes out on its travels, and comes home with a remembrance
of what it has seen."*(2) But until the faculties of imagination,
curiosity, reason, &c., had been fairly well developed in the mind
of man, his dreams would not have led him to believe in spirits, any
more than in the case of a dog.
* "The Worship of Animals and Plants," in the Fortnightly Review,
Oct. 1, 1869, p. 422.
*(2) Tylor, Early History of Mankind, 1865, p. 6. See also the three
striking chapters on the "Development of Religion," in Lubbock's
Origin of Civilisation, 1870. In a like manner Mr. Herbert Spencer, in
his ingenious essay in the Fortnightly Review (May 1, 1870, p. 535),
accounts for the earliest forms of religious belief throughout the
world, by man being led through dreams, shadows, and other causes,
to look at himself as a double essence, corporeal and spiritual. As
the spiritual being is supposed to exist after death and to be
powerful, it is propitiated by various gifts and ceremonies, and its
aid invoked. He then further shews that names or nicknames given
from some animal or other object, to the early progenitors or founders
of a tribe, are supposed after a long interval to represent the real
progenitor of the tribe; and such animal or object is then naturally
believed still to exist as a spirit, is held sacred, and worshipped as
a god. Nevertheless I cannot but suspect that there is a still earlier
and ruder stage, when anything which manifests power or movement is
thought to be endowed with some form of life, and with mental
faculties analogous to our own.
The tendency in savages to imagine that natural objects and agencies
are animated by spiritual or living essences, is perhaps illustrated
by a little fact which I once noticed: my dog, a full-grown and very
sensible animal, was lying on the lawn during a hot and still day; but
at a little distance a slight breeze occasionally moved an open
parasol, which would have been wholly disregarded by the dog, had
any one stood near it. As it was, every time that the parasol slightly
moved, the dog growled fiercely and barked. He must, I think, have
reasoned to himself in a rapid and unconscious manner, that movement
without any apparent cause indicated the presence of some strange
living agent, and that no stranger had a right to be on his territory.
The belief in spiritual agencies would easily pass into the belief
in the existence of one or more gods. For savages would naturally
attribute to spirits the same passions, the same love of vengeance
or simplest form of justice, and the same affections which they
themselves feel. The Fuegians appear to be in this respect in an
intermediate condition, for when the surgeon on board the Beagle
shot some young ducklings as specimens, York Minster declared in the
most solemn manner, "Oh, Mr. Bynoe, much rain, much snow, blow
much"; and this was evidently a retributive punishment for wasting
human food. So again he related how, when his brother killed a "wild
man," storms long raged, much rain and snow fell. Yet we could never
discover that the Fuegians believed in what we should call a God, or
practised any religious rites; and Jemmy Button, with justifiable
pride, stoutly maintained that there was no devil in his land. This
latter assertion is the more remarkable, as with savages the belief in
bad spirits is far more common than that in good ones.
The feeling of religious devotion is a highly complex one,
consisting of love, complete submission to an exalted and mysterious
superior, a strong sense of dependence,* fear, reverence, gratitude,
hope for the future, and perhaps other elements. No being could
experience so complex an emotion until advanced in his intellectual
and moral faculties to at least a moderately high level. Nevertheless,
we see some distant approach to this state of mind in the deep love of
a dog for his master, associated with complete submission, some
fear, and perhaps other feelings. The behaviour of a dog when
returning to his master after an absence, and, as I may add, of a
monkey to his beloved keeper, is widely different from that towards
their fellows. In the latter case the transports of joy appear to be
somewhat less, and the sense of equality is shewn in every action.
Professor Braubach goes so far as to maintain that a dog looks on
his master as on a god.*(2)
* See an able article on the "Physical Elements of Religion," by Mr.
L. Owen Pike, in Anthropological Review, April, 1870, p. lxiii.
*(2) Religion, Moral, &c., der Darwin'schen Art-Lehre, 1869, s.
53. It is said (Dr. W. Lauder Lindsay, Journal of Mental Science,
1871, p. 43), that Bacon long ago, and the poet Burns, held the same
notion.
The same high mental faculties which first led man to believe in
unseen spiritual agencies, then in fetishism, polytheism, and
ultimately in monotheism, would infallibly lead him, as long as his
reasoning powers remained poorly developed, to various strange
superstitions and customs. Many of these are terrible to think of-
such as the sacrifice of human beings to a blood-loving god; the trial
of innocent persons by the ordeal of poison or fire; witchcraft,
&c.- yet it is well occasionally to reflect on these superstitions,
for they shew us what an infinite debt of gratitude we owe to the
improvement of our reason, to science, and to our accumulated
knowledge. As Sir J. Lubbock* has well observed, "it is not too much
to say that the horrible dread of unknown evil hangs like a thick
cloud over savage life, and embitters every pleasure." These miserable
and indirect consequences of our highest faculties may be compared
with the incidental and occasional mistakes of the instincts of the
lower animals.
* Prehistoric Times, 2nd ed., p. 571. In this work (p. 571) there
will be found an excellent account of the many strange and
capricious customs of savages.
CHAPTER IV.
COMPARISON OF THE MENTAL POWERS OF MAN AND THE
LOWER ANIMALS (Continued).
I FULLY subscribe to the judgment of those writers* who maintain
that of all the differences between man and the lower animals, the
moral sense or conscience is by far the most important. This sense, as
Mackintosh*(2) remarks, "has a rightful supremacy over every other
principle of human action"; it is summed up in that short but
imperious word ought, so full of high significance. It is the most
noble of all the attributes of man, leading him without a moment's
hesitation to risk his life for that of a fellow-creature; or after
due deliberation, impelled simply by the deep feeling of right or
duty, to sacrifice it in some great cause. Immanuel Kant exclaims,
"Duty! Wondrous thought, that workest neither by fond insinuation,
flattery, nor by any threat, but merely by holding up thy naked law in
the soul, and so extorting for thyself always reverence, if not always
obedience; before whom all appetites are dumb, however secretly they
rebel; whence thy original?"*(3)
* See, for instance, on this subject, Quatrefages, Unite de l'Espece
Humaine, 1861, p. 21, &c.
*(2) Dissertation an Ethical Philosophy, 1837, p. 231, &c.
*(3) Metaphysics of Ethics translated by J. W. Semple, Edinburgh,
1836, p. 136.
This great question has been discussed by many writers* of
consummate ability; and my sole excuse for touching on it, is the
impossibility of here passing it over; and because, as far as I
know, no one has approached it exclusively from the side of natural
history. The investigation possesses, also, some independent interest,
as an attempt to see how far the study of the lower animals throws
light on one of the highest psychical faculties of man.
* Mr. Bain gives a list (Mental and Moral Science, 1868, pp.
543-725) of twenty-six British authors who have written on this
subject, and whose names are familiar to every reader; to these, Mr.
Bain's own name, and those of Mr. Lecky, Mr. Shadworth Hodgson, Sir J.
Lubbock, and others, might be added.
The following proposition seems to me in a high degree probable-
namely, that any animal whatever, endowed with well-marked social
instincts,* the parental and filial affections being here included,
would inevitably acquire a moral sense or conscience, as soon as its
intellectual powers had become as well, or nearly as well developed,
as in man. For, firstly, the social instincts lead an animal to take
pleasure in the society of its fellows, to feel a certain amount of
sympathy with them, and to perform various services for them. The
services may be of a definite and evidently instinctive nature; or
there may be only a wish and readiness, as with most of the higher
social animals, to aid their fellows in certain general ways. But
these feelings and services are by no means extended to all the
individuals of the same species, only to those of the same
association. Secondly, as soon as the mental faculties had become
highly developed, images of all past actions and motives would be
incessantly passing through the brain of each individual: and that
feeling of dissatisfaction, or even misery, which invariably
results, as we shall hereafter see, from any unsatisfied instinct,
would arise, as often as it was perceived that the enduring and always
present social instinct had yielded to some other instinct, at the
time stronger, but neither enduring in its nature, nor leaving
behind it a very vivid impression. It is clear that many instinctive
desires, such as that of hunger, are in their nature of short
duration; and after being satisfied, are not readily or vividly
recalled. Thirdly, after the power of language had been acquired,
and the wishes of the community could be expressed, the common opinion
how each member ought to act for the public good, would naturally
become in a paramount degree the guide to action. But it should be
borne in mind that however great weight we may attribute to public
opinion, our regard for the approbation and disapprobation of our
fellows depends on sympathy, which, as we shall see, forms an
essential part of the social instinct, and is indeed its
foundation-stone. Lastly, habit in the individual would ultimately
play a very important part in guiding the conduct of each member;
for the social instinct, together with sympathy, is, like any other
instinct, greatly strengthened by habit, and so consequently would
be obedience to the wishes and judgment of the community. These
several subordinate propositions must now be discussed, and some of
them at considerable length.
* Sir B. Brodie, after observing that man is a social animal
(Psychological Enquiries, 1854, p. 192), asks the pregnant question,
"Ought not this to settle the disputed question as to the existence of
a moral sense?" Similar ideas have probably occurred to many
persons, as they did long ago to Marcus Aurelius. Mr. J. S. Mill
speaks, in his celebrated work, Utilitarianism, pp. 459, 460, of the
social feelings as a "powerful natural sentiment," and as "the natural
basis of sentiment for utilitarian morality." Again he says, "Like the
other acquired capacities above referred to, the moral faculty, if not
a part of our nature, is a natural out-growth from it; capable, like
them, in a certain small degree of springing up spontaneously." But in
opposition to all this, he also remarks, "If, as in my own belief, the
moral feelings are not innate, but acquired, they are not for that
reason less natural." It is with hesitation that I venture to differ
at all from so profound a thinker, but it can hardly be disputed
that the social feelings are instinctive or innate in the lower
animals; and why should they not be so in man? Mr. Bain (see, for
instance, The Emotions and the Will, 1865, p. 481) and others
believe that the moral sense is acquired by each individual during his
lifetime. On the general theory of evolution this is at least
extremely improbable. The ignoring of all transmitted mental qualities
will, as it seems to me, be hereafter judged as a most serious blemish
in the works of Mr. Mill.
It may be well first to premise that I do not wish to maintain
that any strictly social animal, if its intellectual faculties were to
become as active and as highly developed as in man, would acquire
exactly the same moral sense as ours. In the same manner as various
animals have some sense of beauty, though they admire widely-different
objects, so they might have a sense of right and wrong, though led
by it to follow widely different lines of conduct. If, for instance,
to take an extreme case, men were reared under precisely the same
conditions as hive-bees, there can hardly be a doubt that our
unmarried females would, like the worker-bees, think it a sacred
duty to kill their brothers, and mothers would strive to kill their
fertile daughters; and no one would think of interfering.*
Nevertheless, the bee, or any other social animal, would gain in our
supposed case, as it appears to me, some feeling of right or wrong, or
a conscience. For each individual would have an inward sense of
possessing certain stronger or more enduring instincts, and others
less strong or enduring; so that there would often be a struggle as to
which impulse should be followed; and satisfaction, dissatisfaction,
or even misery would be felt, as past impressions were compared during
their incessant passage through the mind. In this case an inward
monitor would tell the animal that it would have been better to have
followed the one impulse rather than the other. The one course ought
to have been followed, and the other ought not; the one would have
been right and the other wrong; but to these terms I shall recur.
Mr. H. Sidgwick remarks, in an able discussion on this subject
(the Academy, June 15, 1872, p. 231), "A superior bee, we may feel
sure, would aspire to a milder solution of the popular question."
Judging, however, from the habits of many or most savages, man
solves the problem by female infanticide, polyandry and promiscuous
intercourse; therefore it may well be doubted whether it would be by a
milder method. Miss Cobbe, in commenting ("Darwinism in Morals,"
Theological Review, April, 1872, pp. 188-191) on the same
illustration, says, the principles of social duty would be thus
reversed; and by this, I presume, she means that the fulfillment of
a social duty would tend to the injury of individuals; but she
overlooks the fact, which she would doubtless admit, that the
instincts of the bee have been acquired for the good of the community.
She goes so far as to say that if the theory of ethics advocated in
this chapter were ever generally accepted, "I cannot but believe
that in the hour of their triumph would be sounded the knell of the
virtue of mankind!" It is to be hoped that the belief in the
permanence of virtue on this earth is not held by many persons on so
weak a tenure.
Sociability.- Animals of many kinds are social; we find even
distinct species living together; for example, some American
monkeys; and united flocks of rooks, jackdaws, and starlings. Man
shews the same feeling in his strong love for the dog, which the dog
returns with interest. Every one must have noticed how miserable
horses, dogs, sheep, &c., are when separated from their companions,
and what strong mutual affection the two former kinds, at least,
shew on their reunion. It is curious to speculate on the feelings of a
dog, who will rest peacefully for hours in a room with his master or
any of the family, without the least notice being taken of him; but if
left for a short time by himself, barks or howls dismally. We will
confine our attention to the higher social animals; and pass over
insects, although some of these are social, and aid one another in
many important ways. The most common mutual service in the higher
animals is to warn one another of danger by means of the united senses
of all. Every sportsman knows, as Dr. Jaeger remarks,* how difficult
it is to approach animals in a herd or troop. Wild horses and cattle
do not, I believe, make any danger-signal; but the attitude of any one
of them who first discovers an enemy, warns the others. Rabbits
stamp loudly on the ground with their hindfeet as a signal: sheep
and chamois do the same with their forefeet, uttering likewise a
whistle. Many birds, and some mammals, post sentinels, which in the
case of seals are said*(2) generally to be the females. The leader
of a troop of monkeys acts as the sentinel, and utters cries
expressive both of danger and of safety.*(3) Social animals perform
many little services for each other: horses nibble, and cows lick each
other, on any spot which itches: monkeys search each other for
external parasites; and Brehm states that after a troop of the
Cercopithecus griseoviridis has rushed through a thorny brake, each
monkey stretches itself on a branch, and another monkey sitting by,
"conscientiously" examines its fur, and extracts every thorn or burr.
* Die Darwin'sche Theorie, s. 101.
*(2) Mr. R. Brown in Proc. Zoolog. Soc., 1868, p. 409.
*(3) Brehm, Illustriertes Thierleben, B. i., 1864, ss. 52, 79. For
the case of the monkeys extracting thorns from each other, see s.
54. With respect to the Hamadryas turning over stones, the fact is
given (s. 76), on the evidence of Alvarez, whose observations Brehm
thinks quite trustworthy. For the cases of the old male baboons
attacking the dogs, see s. 79; and with respect to the eagle, s. 56.
Animals also render more important services to one another: thus
wolves and some other beasts of prey hunt in packs, and aid one
another in attacking their victims. Pelicans fish in concert. The
Hamadryas baboons turn over stones to find insects, &c.; and when they
come to a large one, as many as can stand round, turn it over together
and share the booty. Social animals mutually defend each other. Bull
bisons in N. America, when there is danger, drive the cows and
calves into the middle of the herd, whilst they defend the outside.
I shall also in a future chapter give an account of two young wild
bulls at Chillingham attacking an old one in concert, and of two
stallions together trying to drive away a third stallion from a
troop of mares. In Abyssinia, Brehm encountered a great troop of
baboons who were crossing a valley; some had already ascended the
opposite mountain, and some were still in the valley; the latter
were attacked by the dogs, but the old males immediately hurried
down from the rocks, and with mouths widely opened, roared so
fearfully, that the dogs quickly drew back. They were again encouraged
to the attack; but by this time all the baboons had reascended the
heights, excepting a young one, about six months old, who, loudly
calling for aid, climbed on a block of rock, and was surrounded. Now
one of the largest males, a true hero, came down again from the
mountain, slowly went to the young one, coaxed him, and triumphantly
led him away- the dogs being too much astonished to make an attack.
I cannot resist giving another scene which was witnessed by this
same naturalist; an eagle seized a young Cercopithecus, which, by
clinging to a branch, was not at once carried off; it cried loudly for
assistance, upon which the other members of the troop, with much
uproar, rushed to the rescue, surrounded the eagle, and pulled out
so many feathers, that he no longer thought of his prey, but only
how to escape. This eagle, as Brehm remarks, assuredly would never
again attack a single monkey of a troop.*
* Mr. Belt gives the case of a spider-monkey (Ateles) in
Nicaragua, which was heard screaming for nearly two hours in the
forest, and was found with an eagle perched close by it. The bird
apparently feared to attack as long as it remained face to face; and
Mr. Belt believes, from what he has seen of the habits of these
monkeys, that they protect themselves from eagles by keeping two or
three together. The Naturalist in Nicaragua, 1874, p. 118.
It is certain that associated animals have a feeling of love for
each other, which is not felt by non-social adult animals. How far
in most cases they actually sympathise in the pains and pleasures of
others, is more doubtful, especially with respect to pleasures. Mr.
Buxton, however, who had excellent means of observation,* states
that his macaws, which lived free in Norfolk, took "an extravagant
interest" in a pair with a nest; and whenever the female left it,
she was surrounded by a troop "screaming horrible acclamations in
her honour." It is often difficult to judge whether animals have any
feeling for the sufferings of others of their kind. Who can say what
cows feel, when they surround and stare intently on a dying or dead
companion; apparently, however, as Houzeau remarks, they feel no pity.
That animals sometimes are far from feeling any sympathy is too
certain; for they will expel a wounded animal from the herd, or gore
or worry it to death. This is almost the blackest fact in natural
history, unless, indeed, the explanation which has been suggested is
true, that their instinct or reason leads them to expel an injured
companion, lest beasts of prey, including man, should be tempted to
follow the troop. In this case their conduct is not much worse than
that of the North American Indians, who leave their feeble comrades to
perish on the plains; or the Fijians, who, when their parents get old,
or fall ill, bury them alive.*(2)
* Annals and Magazine of Natural History, November, 1868, p. 382.
*(2) Sir J. Lubbock, Prehistoric Times, 2nd ed., p. 446.
Many animals, however, certainly sympathise with each other's
distress or danger. This is the case even with birds. Captain
Stansbury* found on a salt lake in Utah an old and completely blind
pelican, which was very fat, and must have been well fed for a long
time by his companions. Mr. Blyth, as he informs me, saw Indian
crows feeding two or three of their companions which were blind; and I
have heard of an analogous case with the domestic cock. We may, if
we choose, call these actions instinctive; but such cases are much too
rare for the development of any special instinct.*(2) I have myself
seen a dog, who never passed a cat who lay sick in a basket, and was a
great friend of his, without giving her a few licks with his tongue,
the surest sign of kind feeling in a dog.
* As quoted by Mr. L. H. Morgan, The American Beaver, 1868, p.
272. Capt. Stansbury also gives an interesting account of the manner
in which a very young pelican, carried away by a strong stream, was
guided and encouraged in its attempts to reach the shore by half a
dozen old birds.
*(2) As Mr. Bain states, "Effective aid to a sufferer springs from
sympathy proper": Mental and Moral Science, 1868, p. 245.
It must be called sympathy that leads a courageous dog to fly at any
one who strikes his master, as he certainly will. I saw a person
pretending to beat a lady, who had a very timid little dog on her lap,
and the trial had never been made before; the little creature
instantly jumped away, but after the pretended beating was over, it
was really pathetic to see how perseveringly he tried to lick his
mistress's face, and comfort her. Brehm* states that when a baboon
in confinement was pursued to be punished, the others tried to protect
him. It must have been sympathy in the cases above given which led the
baboons and Cercopitheci to defend their young comrades from the
dogs and the eagle. I will give only one other instance of sympathetic
and heroic conduct, in the case of a little American monkey. Several
years ago a keeper at the Zoological Gardens showed me some deep and
scarcely healed wounds on the nape of his own neck, inflicted on
him, whilst kneeling on the floor, by a fierce baboon. The little
American monkey, who was a warm friend of this keeper, lived in the
same compartment, and was dreadfully afraid of the great baboon.
Nevertheless, as soon as he saw his friend in peril, he rushed to
the rescue, and by screams and bites so distracted the baboon that the
man was able to escape, after, as the surgeon thought, running great
risk of his life.
* Illustriertes Thierleben, B. i., s. 85.
Besides love and sympathy, animals exhibit other qualities connected
with the social instincts, which in us would be called moral; and I
agree with Agassiz* that dogs possess something very like a
conscience.
* De l'Espece et de la Classe, 1869, p. 97.
Dogs possess some power of self-command, and this does not appear to
be wholly the result of fear. As Braubach* remarks, they will
refrain from stealing food in the absence of their master. They have
long been accepted as the very type of fidelity and obedience. But the
elephant is likewise very faithful to his driver or keeper, and
probably considers him as the leader of the herd. Dr. Hooker informs
me that an elephant, which he was riding in India, became so deeply
bogged that he remained stuck fast until the next day, when he was
extricated by men with ropes. Under such circumstances elephants
will seize with their trunks any object, dead or alive, to place under
their knees, to prevent their sinking deeper in the mud; and the
driver was dreadfully afraid lest the animal should have seized Dr.
Hooker and crushed him to death. But the driver himself, as Dr. Hooker
was assured, ran no risk. This forbearance under an emergency so
dreadful for a heavy animal, is a wonderful proof of noble
fidelity.*(2)
* Die Darwin'sche Art-Lehre, 1869, s. 54.
*(2) See also Hooker's Himalayan Journals, vol. ii., 1854, p. 333.
All animals living in a body, which defend themselves or attack
their enemies in concert, must indeed be in some degree faithful to
one another; and those that follow a leader must be in some degree
obedient. When the baboons in Abyssinia* plunder a garden, they
silently follow their leader; and if an imprudent young animal makes a
noise, he receives a slap from the others to teach him silence and
obedience. Mr. Galton, who has had excellent opportunities for
observing the half-wild cattle in S. Africa, says,*(2) that they
cannot endure even a momentary separation from the herd. They are
essentially slavish, and accept the common determination, seeking no
better lot than to be led by any one ox who has enough self-reliance
to accept the position. The men who break in these animals for
harness, watch assiduously for those who, by grazing apart, shew a
self-reliant disposition, and these they train as fore-oxen. Mr.
Galton adds that such animals are rare and valuable; and if many
were born they would soon be eliminated, as lions are always on the
look-out for the individuals which wander from the herd.
* Brehm, Illustriertes Thierleben, B. i., s. 76
*(2) See his extremely interesting paper on "Gregariousness in
Cattle, and in Man," Macmillan's Magazine, Feb., 1871, p. 353.
With respect to the impulse which leads certain animals to associate
together, and to aid one another in many ways, we may infer that in
most cases they are impelled by the same sense of satisfaction or
pleasure which they experience in performing other instinctive
actions; or by the same sense of dissatisfaction as when other
instinctive actions are checked. We see this in innumerable instances,
and it is illustrated in a striking manner by the acquired instincts
of our domesticated animals; thus a young shepherd-dog delights in
driving and running round a flock of sheep, but not in worrying
them; a young fox-hound delights in hunting a fox, whilst some other
kinds of dogs, as I have witnessed, utterly disregard foxes. What a
strong feeling of inward satisfaction must impel a bird, so full of
activity, to brood day after day over her eggs. Migratory birds are
quite miserable if stopped from migrating; perhaps they enjoy starting
on their long flight; but it is hard to believe that the poor pinioned
goose, described by Audubon, which started on foot at the proper
time for its journey of probably more than a thousand miles, could
have felt any joy in doing so. Some instincts are determined solely by
painful feelings, as by fear, which leads to self-preservation, and is
in some cases directed towards special enemies. No one, I presume, can
analyse the sensations of pleasure or pain. In many instances,
however, it is probable that instincts are persistently followed
from the mere force of inheritance, without the stimulus of either
pleasure or pain. A young pointer, when it first scents game,
apparently cannot help pointing. A squirrel in a cage who pats the
nuts which it cannot eat, as if to bury them in the ground, can hardly
be thought to act thus, either from pleasure or pain. Hence the common
assumption that men must be impelled to every action by experiencing
some pleasure or pain may be erroneous. Although a habit may be
blindly and implicitly followed, independently of any pleasure or pain
felt at the moment, yet if it be forcibly and abruptly checked, a
vague sense of dissatisfaction is generally experienced.
It has often been assumed that animals were in the first place
rendered social, and that they feel as a consequence uncomfortable
when separated from each other, and comfortable whilst together; but
it is a more probable view that these sensations were first developed,
in order that those animals which would profit by living in society,
should be induced to live together, in the same manner as the sense of
hunger and the pleasure of eating were, no doubt, first acquired in
order to induce animals to eat. The feeling of pleasure from society
is probably an extension of the parental or filial affections, since
the social instinct seems to be developed by the young remaining for a
long time with their parents; and this extension may be attributed
in part to habit, but chiefly to natural selection. With those animals
which were benefited by living in close association, the individuals
which took the greatest pleasure in society would best escape
various dangers, whilst those that cared least for their comrades, and
lived solitary, would perish in greater numbers. With respect to the
origin of the parental and filial affections, which apparently lie
at the base of the social instincts, we know not the steps by which
they have been gained; but we may infer that it has been to a large
extent through natural selection. So it has almost certainly been with
the unusual and opposite feeling of hatred between the nearest
relations, as with the worker-bees which kill their brother drones,
and with the queen-bees which kill their daughter-queens; the desire
to destroy their nearest relations having been in this case of service
to the community. Parental affection, or some feeling which replaces
it, has been developed in certain animals extremely low in the
scale, for example, in star-fishes and spiders. It is also
occasionally present in a few members alone in a whole group of
animals, as in the genus Forficula, or earwigs.
The all-important emotion of sympathy is distinct from that of love.
A mother may passionately love her sleeping and passive infant, but
she can hardly at such times be said to feel sympathy for it. The love
of a man for his dog is distinct from sympathy, and so is that of a
dog for his master. Adam Smith formerly argued, as has Mr. Bain
recently, that the basis of sympathy lies in our strong
retentiveness of former states of pain or pleasure. Hence, "the
sight of another person enduring hunger, cold, fatigue, revives in
us some recollection of these states, which are painful even in idea."
We are thus impelled to relieve the sufferings of another, in order
that our own painful feelings may be at the same time relieved. In
like manner we are led to participate in the pleasures of others.* But
I cannot see how this view explains the fact that sympathy is excited,
in an immeasurably stronger degree, by a beloved, than by an
indifferent person. The mere sight of suffering, independently of
love, would suffice to call up in us vivid recollections and
associations. The explanation may lie in the fact that, with all
animals, sympathy is directed solely towards the members of the same
community, and therefore towards known, and more or less beloved
members, but not to all the individuals of the same species. This fact
is not more surprising than that the fears of many animals should be
directed against special enemies. Species which are not social, such
as lions and tigers, no doubt feel sympathy for the suffering of their
own young, but not for that of any other animal. With mankind,
selfishness, experience, and imitation, probably add, as Mr. Bain
has shown, to the power of sympathy; for we are led by the hope of
receiving good in return to perform acts of sympathetic kindness to
others; and sympathy is much strengthened by habit. In however complex
a manner this feeling may have originated, as it is one of high
importance to all those animals which aid and defend one another, it
will have been increased through natural selection; for those
communities, which included the greatest number of the most
sympathetic members, would flourish best, and rear the greatest number
of offspring.
* See the first and striking chapter in Adam Smith's Theory of Moral
Sentiments. Also Mr. Bain's Mental and Moral Science, 1868, pp. 244,
and 275-282. Mr. Bain states, that, "Sympathy is, indirectly, a source
of pleasure to the sympathiser"; and he accounts for this through
reciprocity. He remarks that "The person benefited, or others in his
stead, may make up, by sympathy and good offices returned, for all the
sacrifice." But if, as appears to be the case, sympathy is strictly an
instinct, its exercise would give direct pleasure, in the same
manner as the exercise, as before remarked, of almost every other
instinct.
It is, however, impossible to decide in many cases whether certain
social instincts have been acquired through natural selection, or
are the indirect result of other instincts and faculties, such as
sympathy, reason, experience, and a tendency to imitation; or again,
whether they are simply the result of long-continued habit. So
remarkable an instinct as the placing sentinels to warn the
community of danger, can hardly have been the indirect result of any
of these faculties; it must, therefore, have been directly acquired.
On the other hand, the habit followed by the males of some social
animals of defending the community, and of attacking their enemies
or their prey in concert, may perhaps have originated from mutual
sympathy; but courage, and in most cases strength, must have been
previously acquired, probably through natural selection.
Of the various instincts and habits, some are much stronger than
others; that is, some either give more pleasure in their
performance, and more distress in their prevention, than others; or,
which is probably quite as important, they are, through inheritance,
more persistently followed, without exciting any special feeling of
pleasure or pain. We are ourselves conscious that some habits are much
more difficult to cure or change than others. Hence a struggle may
often be observed in animals between different instincts, or between
an instinct and some habitual disposition; as when a dog rushes
after a hare, is rebuked, pauses, hesitates, pursues again, or returns
ashamed to his master; or as between the love of a female dog for
her young puppies and for her master,-for she may be seen to slink
away to them, as if half ashamed of not accompanying her master. But
the most curious instance known to me of one instinct getting the
better of another, is the migratory instinct conquering the maternal
instinct. The former is wonderfully strong; a confined bird will at
the proper season beat her breast against the wires of her cage, until
it is bare and bloody. It causes young salmon to leap out of the fresh
water, in which they could continue to exist, and thus unintentionally
to commit suicide. Every one knows how strong the maternal instinct
is, leading even timid birds to face great danger, though with
hesitation, and in opposition to the instinct of self-preservation.
Nevertheless, the migratory instinct is so powerful, that late in
the autumn swallows, house-martins, and swifts frequently desert their
tender young, leaving them to perish miserably in their nests.*
* This fact, the Rev. L. Jenyns states (see his edition of White's
Nat. Hist. of Selborne, 1853, p. 204), was first recorded by the
illustrious Jenner, in Phil. Transact., 1824, and has since been
confirmed by several observers, especially by Mr. Blackwall. This
latter careful observer examined, late in the autumn, during two
years, thirty-six nests; he found that twelve contained young dead
birds, five contained eggs on the point of being hatched, and three,
eggs not nearly hatched. Many birds, not yet old enough for a
prolonged flight, are likewise deserted and left behind. See
Blackwall, Researches in Zoology, 1834, pp. 108, 118. For some
additional evidence, although this is not wanted, see Leroy, Lettres
Phil., 1802, p. 217. For swifts, Gould's Introduction to the Birds
of Great Britain, 1823, p. 5. Similar cases have been observed in
Canada by Mr. Adams; Pop. Science Review, July, 1873, p. 283.
We can perceive that an instinctive impulse, if it be in any way
more beneficial to a species than some other or opposed instinct,
would be rendered the more potent of the two through natural
selection; for the individuals which had it most strongly developed
would survive in larger numbers. Whether this is the case with the
migratory in comparison with the maternal instinct, may be doubted.
The great persistence, or steady action of the former at certain
seasons of the year during the whole day, may give it for a time
paramount force.
Man a social animal.- Every one will admit that man is a social
being. We see this in his dislike of solitude, and in his wish for
society beyond that of his own family. Solitary confinement is one
of the severest punishments which can be inflicted. Some authors
suppose that man primevally lived in single families; but at the
present day, though single families, or only two or three together,
roam the solitudes of some savage lands, they always, as far as I
can discover, hold friendly relations with other families inhabiting
the same district. Such families occasionally meet in council, and
unite for their common defence. It is no argument against savage man
being a social animal, that the tribes inhabiting adjacent districts
are almost always at war with each other; for the social instincts
never extend to all the individuals of the same species. Judging
from the analogy of the majority of the Quadrumana, it is probable
that the early ape-like progenitors of man were likewise social; but
this is not of much importance for us. Although man, as he now exists,
has few special instincts, having lost any which his early progenitors
may have possessed, this is no reason why he should not have
retained from an extremely remote period some degree of instinctive
love and sympathy for his fellows. We are indeed all conscious that we
do possess such sympathetic feelings;* but our consciousness does
not tell us whether they are instinctive, having originated long ago
in the same manner as with the lower animals, or whether they have
been acquired by each of us during our early years. As man is a social
animal, it is almost certain that he would inherit a tendency to be
faithful to his comrades, and obedient to the leader of his tribe; for
these qualities are common to most social animals. He would
consequently possess some capacity for self-command. He would from
an inherited tendency be willing to defend, in concert with others,
his fellow-men; and would be ready to aid them in any way, which did
not too greatly interfere with his own welfare or his own strong
desires.
* Hume remarks (An Enquiry Concerning the Principles of Morals,
ed. of 1751, p. 132), "There seems a necessity for confessing that the
happiness and misery of others are not spectacles altogether
indifferent to us, but that the view of the former... communicates a
secret joy; the appearance of the latter... throws a melancholy damp
over the imagination."
The social animals which stand at the bottom of the scale are guided
almost exclusively, and those which stand higher in the scale are
largely guided, by special instincts in the aid which they give to the
members of the same community; but they are likewise in part
impelled by mutual love and sympathy, assisted apparently by some
amount of reason. Although man, as just remarked, has no special
instincts to tell him how to aid his fellow-men, he still has the
impulse, and with his improved intellectual faculties would
naturally be much guided in this respect by reason and experience.
Instinctive sympathy would also cause him to value highly the
approbation of his fellows; for, as Mr. Bain has clearly shewn,* the
love of praise and the strong feeling of glory, and the still stronger
horror of scorn and infamy, "are due to the workings of sympathy."
Consequently man would be influenced in the highest degree by the
wishes, approbation, and blame of his fellow-men, as expressed by
their gestures and language. Thus the social instincts, which must
have been acquired by man in a very rude state, and probably even by
his early ape-like progenitors, still give the impulse to some of
his best actions; but his actions are in a higher degree determined by
the expressed wishes and judgment of his fellow-men, and unfortunately
very often by his own strong selfish desires. But as love, sympathy
and self-command become strengthened by habit, and as the power of
reasoning becomes clearer, so that man can value justly the
judgments of his fellows, he will feel himself impelled, apart from
any transitory pleasure or pain, to certain lines of conduct. He might
then declare- not that any barbarian or uncultivated man could thus
think- I am the supreme judge of my own conduct, and in the words of
Kant, I will not in my own person violate the dignity of humanity.
* Mental and Moral Science, 1868, p. 254.
The more enduring Social Instincts conquer the less persistent
Instincts.- We have not, however, as yet considered the main point, on
which, from our present point of view, the whole question of the moral
sense turns. Why should a man feel that he ought to obey one
instinctive desire rather than another? Why is he bitterly
regretful, if he has yielded to a strong sense of self-preservation,
and has not risked his life to save that of a fellow-creature? Or
why does he regret having stolen food from hunger?
It is evident in the first place, that with mankind the
instinctive impulses have different degrees of strength; a savage will
risk his own life to save that of a member of the same community,
but will be wholly indifferent about a stranger: a young and timid
mother urged by the maternal instinct will, without a moment's
hesitation, run the greatest danger for her own infant, but not for
a mere fellow-creature. Nevertheless many a civilized man, or even
boy, who never before risked his life for another, but full of courage
and sympathy, has disregarded the instinct of self-preservation, and
plunged at once into a torrent to save a drowning man, though a
stranger. In this case man is impelled by the same instinctive motive,
which made the heroic little American monkey, formerly described, save
his keeper, by attacking the great and dreaded baboon. Such actions as
the above appear to be the simple result of the greater strength of
the social or maternal instincts rather than that of any other
instinct or motive; for they are performed too instantaneously for
reflection, or for pleasure or pain to be felt at the time; though, if
prevented by any cause, distress or even misery might be felt. In a
timid man, on the other hand, the instinct of self-preservation, might
be so strong, that he would be unable to force himself to run any such
risk, perhaps not even for his own child.
I am aware that some persons maintain that actions performed
impulsively, as in the above cases, do not come under the dominion
of the moral sense, and cannot be called moral. They confine this term
to actions done deliberately, after a victory over opposing desires,
or when prompted by some exalted motive. But it appears scarcely
possible to draw any clear line of distinction of this kind.* As far
as exalted motives are concerned, many instances have been recorded of
savages, destitute of any feeling of general benevolence towards
mankind, and not guided by any religious motive, who have deliberately
sacrificed their lives as prisoners,*(2) rather than betray their
comrades; and surely their conduct ought to be considered as moral. As
far as deliberation, and the victory over opposing motives are
concerned, animals may be seen doubting between opposed instincts,
in rescuing their offspring or comrades from danger; yet their
actions, though done for the good of others, are not called moral.
Moreover, anything performed very often by us, will at last be done
without deliberation or hesitation, and can then hardly be
distinguished from an instinct; yet surely no one will pretend that
such an action ceases to be moral. On the contrary, we all feel that
an act cannot be considered as perfect, or as performed in the most
noble manner, unless it be done impulsively, without deliberation or
effort, in the same manner as by a man in whom the requisite qualities
are innate. He who is forced to overcome his fear or want of
sympathy before he acts, deserves, however, in one way higher credit
than the man whose innate disposition leads him to a good act
without effort. As we cannot distinguish between motives, we rank
all actions of a certain class as moral, if performed by a moral
being. A moral being is one who is capable of comparing his past and
future actions or motives, and of approving or disapproving of them.
We have no reason to suppose that any of the lower animals have this
capacity; therefore, when a Newfoundland dog drags a child out of
the water, or a monkey faces danger to rescue its comrade, or takes
charge of an orphan monkey, we do not call its conduct moral. But in
the case of man, who alone can with certainty be ranked as a moral
being, actions of a certain class are called moral, whether
performed deliberately, after a struggle with opposing motives, or
impulsively through instinct, or from the effects of slowly-gained
habit.
* I refer here to the distinction between what has been called
material and formal morality. I am glad to find that Professor
Huxley (Critiques and Addresses, 1873, p. 287) takes the same view
on this subject as I do. Mr. Leslie Stephen remarks (Essays on Free
Thinking and Plain Speaking, 1873, p. 83), "The metaphysical
distinction between material and formal morality is as irrelevant as
other such distinctions."
*(2) I have given one such case, namely of three Patagonian
Indians who preferred being shot, one after the other, to betraying
the plans of their companions in war (Journal of Researches, 1845,
p. 103).
But to return to our more immediate subject. Although some instincts
are more powerful than others, and thus lead to corresponding actions,
yet it is untenable, that in man the social instincts (including the
love of praise and fear of blame) possess greater strength, or have,
through long habit, acquired greater strength than the instincts of
self-preservation, hunger, lust, vengeance, &c. Why then does man
regret, even though trying to banish such regret, that he has followed
the one natural impulse rather than the other; and why does he further
feel that he ought to regret his conduct? Man in this respect
differs profoundly from the lower animals. Nevertheless we can, I
think, see with some degree of clearness the reason of this
difference.
Man, from the activity of his mental faculties, cannot avoid
reflection: past impressions and images are incessantly and clearly
passing through his mind. Now with those animals which live
permanently in a body, the social instincts are ever present and
persistent. Such animals are always ready to utter the
danger-signal, to defend the community, and to give aid to their
fellows in accordance with their habits; they feel at all times,
without the stimulus of any special passion or desire, some degree
of love and sympathy for them; they are unhappy if long separated from
them, and always happy to be again in their company. So it is with
ourselves. Even when we are quite alone, how often do we think with
pleasure or pain of what others think of us,- of their imagined
approbation or disapprobation; and this all follows from sympathy, a
fundamental element of the social instincts. A man who possessed no
trace of such instincts would be an unnatural monster. On the other
hand, the desire to satisfy hunger, or any passion such as
vengeance, is in its nature temporary, and can for a time be fully
satisfied. Nor is it easy, perhaps hardly possible, to call up with
complete vividness the feeling, for instance, of hunger; nor indeed,
as has often been remarked, of any suffering. The instinct of
self-preservation is not felt except in the presence of danger; and
many a coward has thought himself brave until he has met his enemy
face to face. The wish for another man's property is perhaps as
persistent a desire as any that can be named; but even in this case
the satisfaction of actual possession is generally a weaker feeling
than the desire: many a thief, if not an habitual one, after success
has wondered why he stole some article.*
* Enmity or hatred seems also to be a highly persistent feeling,
perhaps more so than any other that can be named. Envy is defined as
hatred of another for some excellence or success; and Bacon insists
(Essay ix.), "Of all other affections envy is the most importune and
continual." Dogs are very apt to hate both strange men and strange
dogs, especially if they live near at hand, but do not belong to the
same family, tribe, or clan; this feeling would thus seem to be
innate, and is certainly a most persistent one. It seems to be the
complement and converse of the true social instinct. From what we hear
of savages, it would appear that something of the same kind holds good
with them. If this be so, it would be a small step in any one to
transfer such feelings to any member of the same tribe if he had
done him an injury and had become his enemy. Nor is it probable that
the primitive conscience would reproach a man for injuring his
enemy; rather it would reproach him, if he had not revenged himself.
To do good in return for evil, to love your enemy, is a height of
morality to which it may be doubted whether the social instincts
would, by themselves, have ever led us. It is necessary that these
instincts, together with sympathy, should have been highly
cultivated and extended by the aid of reason, instruction, and the
love or fear of God, before any such golden rule would ever be thought
of and obeyed.
A man cannot prevent past impressions often repassing through his
mind; he will thus be driven to make a comparison between the
impressions of past hunger, vengeance satisfied, or danger shunned
at other men's cost, with the almost ever-present instinct of
sympathy, and with his early knowledge of what others consider as
praiseworthy or blameable. This knowledge cannot be banished from
his mind, and from instinctive sympathy is esteemed of great moment.
He will then feel as if he had been baulked in following a present
instinct or habit, and this with all animals causes dissatisfaction,
or even misery.
The above case of the swallow affords an illustration, though of a
reversed nature, of a temporary though for the time strongly
persistent instinct conquering another instinct, which is usually
dominant over all others. At the proper season these birds seem all
day long to be impressed with the desire to migrate; their habits
change; they become restless, are noisy and congregate in flocks.
Whilst the mother-bird is feeding, or brooding over her nestlings, the
maternal instinct is probably stronger than the migratory; but the
instinct which is the more persistent gains the victory, and at
last, at a moment when her young ones are not in sight, she takes
flight and deserts them. When arrived at the end of her long
journey, and the migratory instinct has ceased to act, what an agony
of remorse the bird would feel, if, from being endowed with great
mental activity, she could not prevent the image constantly passing
through her mind, of her young ones perishing in the bleak north
from cold and hunger.
At the moment of action, man will no doubt be apt to follow the
stronger impulse; and though this may occasionally prompt him to the
noblest deeds, it will more commonly lead him to gratify his own
desires at the expense of other men. But after their gratification
when past and weaker impressions are judged by the ever-enduring
social instinct, and by his deep regard for the good opinion of his
fellows, retribution will surely come. He will then feel remorse,
repentance, regret, or shame; this latter feeling, however, relates
almost exclusively to the judgment of others. He will consequently
resolve more or less firmly to act differently for the future; and
this is conscience; for conscience looks backwards, and serves as a
guide for the future.
The nature and strength of the feelings which we call regret, shame,
repentance or remorse, depend apparently not only on the strength of
the violated instinct, but partly on the strength of the temptation,
and often still more on the judgment of our fellows. How far each
man values the appreciation of others, depends on the strength of
his innate or acquired feeling of sympathy; and on his own capacity
for reasoning out the remote consequences of his acts. Another element
is most important, although not necessary, the reverence or fear of
the Gods, or Spirits believed in by each man: and this applies
especially in cases of remorse. Several critics have objected that
though some slight regret or repentance may be explained by the view
advocated in this chapter, it is impossible thus to account for the
soul-shaking feeling of remorse. But I can see little force in this
objection. My critics do not define what they mean by remorse, and I
can find no definition implying more than an overwhelming sense of
repentance. Remorse seems to bear the same relation to repentance,
as rage does to anger, or agony to pain. It is far from strange that
an instinct so strong and so generally admired, as maternal love,
should, if disobeyed, lead to the deepest misery, as soon as the
impression of the past cause of disobedience is weakened. Even when an
action is opposed to no special instinct, merely to know that our
friends and equals despise us for it is enough to cause great
misery. Who can doubt that the refusal to fight a duel through fear
has caused many men an agony of shame? Many a Hindoo, it is said,
has been stirred to the bottom of his soul by having partaken of
unclean food. Here is another case of what must, I think, be called
remorse. Dr. Landor acted as a magistrate in West Australia, and
relates* that a native on his farm, after losing one of his wives from
disease, came and said that, "He was going to a distant tribe to spear
a woman, to satisfy his sense of duty to his wife. I told him that
if he did so, I would send him to prison for life. He remained about
the farm for some months, but got exceedingly thin, and complained
that he could not rest or eat, that his wife's spirit was haunting
him, because he had not taken a life for hers. I was inexorable, and
assured him that nothing should save him if he did." Nevertheless
the man disappeared for more than a year, and then returned in high
condition; and his other wife told Dr. Landor that her husband had
taken the life of a woman belonging to a distant tribe; but it was
impossible to obtain legal evidence of the act. The breach of a rule
held sacred by the tribe, will thus, as it seems, give rise to the
deepest feelings,- and this quite apart from the social instincts,
excepting in so far as the rule is grounded on the judgment of the
community. How so many strange superstitions have arisen throughout
the world we know not; nor can we tell how some real and great crimes,
such as incest, have come to be held in an abhorrence (which is not
however quite universal) by the lowest savages. It is even doubtful
whether in some tribes incest would be looked on with greater
horror, than would the marriage of a man with a woman bearing the same
name, though not a relation. "To violate this law is a crime which the
Australians hold in the greatest abhorrence, in this agreeing
exactly with certain tribes of North America. When the question is put
in either district, is it worse to kill a girl of a foreign tribe,
or to marry a girl of one's own, an answer just opposite to ours would
be given without hesitation."*(2) We may, therefore, reject the
belief, lately insisted on by some writers, that the abhorrence of
incest is due to our possessing a special God-implanted conscience. On
the whole it is intelligible, that a man urged by so powerful a
sentiment as remorse, though arising as above explained, should be led
to act in a manner, which he has been taught to believe serves as an
expiation, such as delivering himself up to justice.
* Insanity in Relation to Law, Ontario, United States, 1871, p. 1.
*(2) E. B. Tylor, in Contemporary Review, April, 1873, p. 707.
Man prompted by his conscience, will through long habit acquire such
perfect self-command, that his desires and passions will at last yield
instantly and without a struggle to his social sympathies and
instincts, including his feeling for the judgment of his fellows.
The still hungry, or the still revengeful man will not think of
stealing food, or of wreaking his vengeance. It is possible, or as
we shall hereafter see, even probable, that the habit of
self-command may, like other habits, be inherited. Thus at last man
comes to feel, through aequired and perhaps inherited habit, that it
is best for him to obey his more persistent impulses. The imperious
word ought seems merely to imply the consciousness of the existence of
a rule of conduct, however it may have originated. Formerly it must
have been often vehemently urged that an insulted gentleman ought to
fight a duel. We even say that a pointer ought to point, and a
retriever to retrieve game. If they fail to do so, they fail in
their duty and act wrongly.
If any desire or instinct leading to an action opposed to the good
of others still appears, when recalled to mind, as strong as, or
stronger than, the social instinct, a man will feel no keen regret
at having followed it; but he will be conscious that if his conduct
were known to his fellows, it would meet with their disapprobation;
and few are so destitute of sympathy as not to feel discomfort when
this is realised. If he has no such sympathy, and if his desires
leading to bad actions are at the time strong, and when recalled are
not over-mastered by the persistent social instincts, and the judgment
of others, then he is essentially a bad man;* and the sole restraining
motive left is the fear of punishment, and the conviction that in
the long run it would be best for his own selfish interests to
regard the good of others rather than his own.
* Dr. Prosper Despine, in his Psychologie Naturelle, 1868 (tom.
i., p. 243; tom. ii., p. 169) gives many curious cases of the worst
criminals who apparently have been entirely destitute of conscience.
It is obvious that every one may with an easy conscience gratify his
own desires, if they do not interfere with his social instincts,
that is with the good of others; but in order to be quite free from
self-reproach, or at least of anxiety, it is almost necessary for
him to avoid the disapprobation, whether reasonable or not, of his
fellow-men. Nor must he break through the fixed habits of his life,
especially if these are supported by reason; for if he does, he will
assuredly feel dissatisfaction. He must likewise avoid the reprobation
of the one God or gods in whom. according to his knowledge or
superstition, he may believe; but in this case the additional fear
of divine punishment often supervenes.
The strictly Social Virtues at first alone regarded.- The above view
of the origin and nature of the moral sense, which tells us what we
ought to do, and of the conscience which reproves us if we disobey it,
accords well with what we see of the early and undeveloped condition
of this faculty in mankind. The virtues which must be practised, at
least generally, by rude men, so that they may associate in a body,
are those which are still recognised as the most important. But they
are practised almost exclusively in relation to the men of the same
tribe; and their opposites are not regarded as crimes in relation to
the men of other tribes. No tribe could hold together if murder,
robbery, treachery, &c., were common; consequently such crimes
within the limits of the same tribe "are branded with everlasting
infamy";* but excite no such sentiment beyond these limits. A
North-American Indian is well pleased with himself, and is honoured by
others, when he scalps a man of another tribe; and a Dyak cuts off the
head of an unoffending person, and dries it as a trophy. The murder of
infants has prevailed on the largest scale throughout the world,*(2)
and has met with no reproach; but infanticide, especially of
females, has been thought to be good for the tribe, or at least not
injurious. Suicide during former times was not generally considered as
a crime,*(3) but rather, from the courage displayed, as an
honourable act; and it is still practised by some semi-civilised and
savage nations without reproach, for it does not obviously concern
others of the tribe. It has been recorded that an Indian Thug
conscientiously regretted that he had not robbed and strangled as many
travellers as did his father before him. In a rude state of
civilisation the robbery of strangers is, indeed, generally considered
as honourable.
* See an able article in the North British Review, 1867, p. 395. See
also Mr. W. Bagehot's articles on the "Importance of Obedience and
Coherence to Primitive Man, " in the Fortnightly Review, 1867, p. 529,
and 1868, p. 457, &c.
*(2) The fullest account which I have met with is by Dr. Gerland, in
his Ober den Aussterben der Naturvolker, 1868: but I shall have to
recur to the subject of infanticide in a future chapter.
*(3) See the very interesting discussion on suicide in Lecky's
History of European Morals, vol. i., 1869, p. 223. With respect to
savages, Mr. Winwood Reade informs me that the negroes of west
Africa often commit suicide. It is well known how common it was
amongst the miserable aborigines of South America after the Spanish
conquest. For New Zealand, see The Voyage of the Novara, and for the
Aleutian Islands, Muller, as quoted by Houzeau, Les Facultes Mentales,
&c., tom. ii., p. 136.
Slavery, although in some ways beneficial during ancient times,*
is a great crime; yet it was not so regarded until quite recently,
even by the most civilised nations. And this was especially the
case, because the slaves belonged in general to a race different
from that of their masters. As barbarians do not regard the opinion of
their women, wives are commonly treated like slaves. Most savages
are utterly indifferent to the sufferings of strangers, or even
delight in witnessing them. It is well known that the women and
children of the North American Indians aided in torturing their
enemies. Some savages take a horrid pleasure in cruelty to
animals,*(2) and humanity is an unknown virtue. Nevertheless,
besides the family affections, kindness is common, especially during
sickness, between the members of the same tribe, and is sometimes
extended beyond these limits. Mungo Park's touching account of the
kindness of the negro women of the interior to him is well known. Many
instances could be given of the noble fidelity of savages towards each
other, but not to strangers; common experience justifies the maxim
of the Spaniard, "Never, never trust an Indian." There cannot be
fidelity without truth; and this fundamental virtue is not rare
between the members of the same tribe: thus Mungo Park heard the negro
women teaching their young children to love the truth. This, again, is
one of the virtues which becomes so deeply rooted in the mind, that it
is sometimes practised by savages, even at a high cost, towards
strangers; but to lie to your enemy has rarely been thought a sin,
as the history of modern diplomacy too plainly shews. As soon as a
tribe has a recognised leader, disobedience becomes a crime, and
even abject submission is looked at as a sacred virtue.
* See Mr. Bagehot, Physics and Politics, 1872, p. 72.
*(2) See, for instance, Mr. Hamilton's account of the Kaffirs,
Anthropological Review, 1870, p. xv.
As during rude times no man can be useful or faithful to his tribe
without courage, this quality has universally been placed in the
highest rank; and although in civilised countries a good yet timid man
may be far more useful to the community than a brave one, we cannot
help instinctively honouring the latter above a coward, however
benevolent. Prudence, on the other hand, which does not concern the
welfare of others, though a very useful virtue, has never been
highly esteemed. As no man can practise the virtues necessary for
the welfare of his tribe without self-sacrifice, self-command, and the
power of endurance, these qualities have been at all times highly
and most justly valued. The American savage voluntarily submits to the
most horrid tortures without a groan, to prove and strengthen his
fortitude and courage; and we cannot help admiring him, or even an
Indian Fakir, who, from a foolish religious motive, swings suspended
by a hook buried in his flesh.
The other so-called self-regarding virtues, which do not
obviously, though they may really, affect the welfare of the tribe,
have never been esteemed by savages, though now highly appreciated
by civilised nations. The greatest intemperance is no reproach with
savages. Utter licentiousness, and unnatural crimes, prevail to an
astounding extent.* As soon, however, as marriage, whether polygamous,
or monogamous, becomes common, jealousy will lead to the inculcation
of female virtue; and this, being honoured, will tend to spread to the
unmarried females. How slowly it spreads to the male sex, we see at
the present day. Chastity eminently requires self-command;
therefore, it has been honoured from a very early period in the
moral history of civilised man. As a consequence of this, the
senseless practice of celibacy has been ranked from a remote period as
a virtue.*(2) The hatred of indecency, which appears to us so
natural as to be thought innate, and which is so valuable an aid to
chastity, is a modern virtue, appertaining exclusively, as Sir G.
Staunton remarks,*(3) to civilised life. This is shewn by the
ancient religious rites of various nations, by the drawings on the
walls of Pompeii, and by the practices of many savages.
* Mr. M'Lennan has given (Primitive Marriage, 1865, p. 176) a good
collection of facts on this head.
*(2) Lecky, History of European Morals, vol. i., 1869, p. 109.
*(3) Embassy to China, vol. ii., p. 348.
We have now seen that actions are regarded by savages, and were
probably so regarded by primeval man, as good or bad, solely as they
obviously affect the welfare of the tribe,- not that of the species,
nor that of an individual member of the tribe. This conclusion
agrees well with the belief that the so-called moral sense is
aboriginally derived from the social instincts, for both relate at
first exclusively to the community.
The chief causes of the low morality of savages, as judged by our
standard, are, firstly, the confinement of sympathy to the same tribe.
Secondly, powers of reasoning insufficient to recognise the bearing of
many virtues, especially of the self-regarding virtues, on the general
welfare of the tribe. Savages, for instance, fail to trace the
multiplied evils consequent on a want of temperance, chastity, &c.
And, thirdly, weak power of self-command; for this power has not
been strengthened through long-continued, perhaps inherited, habit,
instruction and religion.
I have entered into the above details on the immorality of savages,*
because some authors have recently taken a high view of their moral
nature, or have attributed most of their crimes to mistaken
benevolence.*(2) These authors appear to rest their conclusion on
savages possessing those virtues which are serviceable, or even
necessary, for the existence of the family and of the tribe,-
qualities which they undoubtedly do possess, and often in a high
degree.
* See on this subject copious evidence in chap. vii. of Sir J.
Lubbock, Origin of Civilisation, 1870.
*(2) For instance Lecky, History of European Morals, vol. i., p.
124.
Concluding Remarks.- It was assumed formerly by philosophers of
the derivative* school of morals that the foundation of morality lay
in a form of Selfishness; but more recently the "Greatest happiness
principle" has been brought prominently forward. It is, however,
more correct to speak of the latter principle as the standard, and not
as the motive of conduct. Nevertheless, all the authors whose works
I have consulted, with a few exceptions,*(2) write as if there must be
a distinct motive for every action, and that this must be associated
with some pleasure or displeasure. But man seems often to act
impulsively, that is from instinct or long habit, without any
consciousness of pleasure, in the same manner as does probably a bee
or ant, when it blindly follows its instincts. Under circumstances
of extreme peril, as during a fire, when a man endeavours to save a
fellow-creature without a moment's hesitation, he can hardly feel
pleasure; and still less has he time to reflect on the dissatisfaction
which he might subsequently experience if he did not make the attempt.
Should he afterwards reflect over his own conduct, he would feel
that there lies within him an impulsive power widely different from
a search after pleasure or happiness; and this seems to be the
deeply planted social instinct.
* This term is used in an able article in the Westminster Review,
Oct., 1869, p. 498; For the "Greatest happiness principle," see J.
S. Mill, Utilitarianism, p. 448.
*(2) Mill recognises (System of Logic, vol. ii., p. 422) in the
clearest manner, that actions may be performed through habit without
the anticipation of pleasure. Mr. H. Sidgwick also, in his "Essay on
Pleasure and Desire" (The Contemporary Review, April, 1872, p. 671),
remarks: "To sum up, in contravention of the doctrine that our
conscious active impulses are always directed towards the production
of agreeable sensations in ourselves, I would maintain that we find
everywhere in consciousness extra-regarding impulse, directed
towards something that is not pleasure; that in many case the
impulse is so far incompatible with the self-regarding that the two do
not easily co-exist in the same moment of consciousness." A dim
feeling that our impulses do not by any means always arise from any
contemporaneous or anticipated pleasure, has, I cannot but think, been
one chief cause of the acceptance of the intuitive theory of morality,
and of the rejection of the utilitarian or "Greatest happiness"
theory. With respect to the latter theory the standard and the
motive of conduct have no doubt often been confused, but they are
really in some degree blended.
In the case of the lower animals it seems much more appropriate to
speak of their social instincts, as having been developed for the
general good rather than for the general happiness of the species. The
term, general good, may be defined as the rearing of the greatest
number of individuals in full vigour and health, with all their
faculties perfect, under the conditions to which they are subjected.
As the social instincts both of man and the lower animals have no
doubt been developed by nearly the same steps, it would be
advisable, if found practicable, to use the same definition in both
cases, and to take as the standard of morality, the general good or
welfare of the community, rather than the general happiness; but
this definition would perhaps require some limitation on account of
political ethics.
When a man risks his life to save that of a fellow-creature, it
seems also more correct to say that he acts for the general good,
rather than for the general happiness of mankind. No doubt the welfare
and the happiness of the individual usually coincide; and a contented,
happy tribe will flourish better than one that is discontented and
unhappy. We have seen that even at an early period in the history of
man, the expressed wishes of the community will have naturally
influenced to a large extent the conduct of each member; and as all
wish for happiness, the "greatest happiness principle" will have
become a most important secondary guide and object; the social
instinct, however, together with sympathy (which leads to our
regarding the approbation and disapprobation of others), having served
as the primary impulse and guide. Thus the reproach is removed of
laying the foundation of the noblest part of our nature in the base
principle of selfishness; unless, indeed, the satisfaction which every
animal feels, when it follows its proper instincts, and the
dissatisfaction felt when prevented, be called selfish.
The wishes and opinions of the members of the same community,
expressed at first orally, but later by writing also, either form
the sole guides of our conduct, or greatly reinforce the social
instincts; such opinions, however, have sometimes a tendency
directly opposed to these instincts. This latter fact is well
exemplified by the Law of Honour, that is, the law of the opinion of
our equals, and not of all our countrymen. The breach of this law,
even when the breach is known to be strictly accordant with true
morality, has caused many a man more agony than a real crime. We
recognise the same influence in the burning sense of shame which
most of us have felt, even after the interval of years, when calling
to mind some accidental breach of a trifling, though fixed, rule of
etiquette. The judgment of the community will generally be guided by
some rude experience of what is best in the long run for all the
members; but this judgment will not rarely err from ignorance and weak
powers of reasoning. Hence the strangest customs and superstitions, in
complete opposition to the true welfare and happiness of mankind, have
become all-powerful throughout the world. We see this in the horror
felt by a Hindoo who breaks his caste, and in many other such cases.
It would be difficult to distinguish between the remorse felt by a
Hindoo who has yielded to the temptation of eating unclean food,
from that felt after committing a theft; but the former would probably
be the more severe.
How so many absurd rules of conduct, as well as so many absurd
religious beliefs, have originated, we do not know; nor how it is that
they have become, in all quarters of the world, so deeply impressed on
the mind of men; but it is worthy of remark that a belief constantly
inculcated during the early years of life, whilst the brain is
impressible, appears to acquire almost the nature of an instinct;
and the very essence of an instinct is that it is followed
independently of reason. Neither can we say why certain admirable
virtues, such as the love of truth, are much more highly appreciated
by some savage tribes than by others;* nor, again, why similar
differences prevail even amongst highly civilised nations. Knowing how
firmly fixed many strange customs and superstitions have become, we
need feel no surprise that the self-regarding virtues, supported as
they are by reason, should now appear to us so natural as to be
thought innate, although they were not valued by man in his early
condition.
* Good instances are given by Mr. Wallace in Scientific Opinion,
Sept. 15, 1869; and more fully in his Contributions to the Theory of
Natural Selection, 1870, p. 353.
Not withstanding many sources of doubt, man can generally and
readily distinguish between the higher and lower moral rules. The
higher are founded on the social instincts, and relate to the
welfare of others. They are supported by the approbation of our
fellow-men and by reason. The lower rules, though some of them when
implying self-sacrifice hardly deserve to be called lower, relate
chiefly to self, and arise from public opinion, matured by
experience and cultivation; for they are not practised by rude tribes.
As man advances in civilisation, and small tribes are united into
larger communities, the simplest reason would tell each individual
that he ought to extend his social instincts and sympathies to all the
members of the same nation, though personally unknown to him. This
point being once reached, there is only an artificial barrier to
prevent his sympathies extending to the men of all nations and
races. If, indeed, such men are separated from him by great
differences in appearance or habits, experience unfortunately shews us
how long it is, before we look at them as our fellow-creatures.
Sympathy beyond the confines of man, that is, humanity to the lower
animals, seems to be one of the latest moral acquisitions. It is
apparently unfelt by savages, except towards their pets. How little
the old Romans knew of it is shewn by their abhorrent gladiatorial
exhibitions. The very idea of humanity, as far as I could observe, was
new to most of the Gauchos of the Pampas. This virtue, one of the
noblest with which man is endowed, seems to arise incidentally from
our sympathies becoming more tender and more widely diffused, until
they are extended to all sentient beings. As soon as this virtue is
honoured and practised by some few men, it spreads through instruction
and example to the young, and eventually becomes incorporated in
public opinion.
The highest possible stage in moral culture is when we recognise
that we ought to control our thoughts, and "not even in inmost thought
to think again the sins that made the past so pleasant to us."*
Whatever makes any bad action familiar to the mind, renders its
performance by so much the easier. As Marcus Aurelius long ago said,
"Such as are thy habitual thoughts, such also will be the character of
thy mind; for the soul is dyed by the thoughts."*(2)
* Tennyson, Idylls of the King, p. 244.
*(2) Marcus Aurelius, Meditations, Bk. V, sect. 16.
Our great philosopher, Herbert Spencer, has recently explained his
views on the moral sense. He says, "I believe that the experiences
of utility organised and consolidated through all past generations
of the human race, have been producing corresponding modifications,
which, by continued transmission and accumulation, have become in us
certain faculties of moral intuition- certain emotions responding to
right and wrong conduct, which have no apparent basis in the
individual experiences of utility."* There is not the least inherent
improbability, as it seems to me, in virtuous tendencies being more or
less strongly inherited; for, not to mention the various
dispositions and habits transmitted by many of our domestic animals to
their offspring, I have heard of authentic cases in which a desire
to steal and a tendency to lie appeared to run in families of the
upper ranks; and as stealing is a rare crime in the wealthy classes,
we can hardly account by accidental coincidence for the tendency
occurring in two or three members of the same family. If bad
tendencies are transmitted, it is probable that good ones are likewise
transmitted. That the state of the body by affecting the brain, has
great influence on the moral tendencies is known to most of those
who have suffered from chronic derangements of the digestion or liver.
The same fact is likewise shewn by the "perversion or destruction of
the moral sense being often one of the earliest symptoms of mental
derangement";*(2) and insanity is notoriously often inherited.
Except through the principle of the transmission of moral
tendencies, we cannot understand the differences believed to exist
in this respect between the various races of mankind.
* Letter to Mr. Mill in Bain's Mental and Moral Science, 1868, p.
722.
*(2) Maudsley, Body and Mind, 1870, p. 60.
Even the partial transmission of virtuous tendencies would be an
immense assistance to the primary impulse derived directly and
indirectly from the social instincts. Admitting for a moment that
virtuous tendencies are inherited, it appears probable, at least in
such cases as chastity, temperance, humanity to animals, &c., that
they become first impressed on the mental organization through
habit, instruction and example, continued during several generations
in the same family, and in a quite subordinate degree, or not at
all, by the individuals possessing such virtues having succeeded
best in the struggle for life. My chief source of doubt with respect
to any such inheritance, is that senseless customs, superstitions, and
tastes, such as the horror of a Hindoo for unclean food, ought on
the same principle to be transmitted. I have not met with any evidence
in support of the transmission of superstitious customs or senseless
habits, although in itself it is perhaps not less probable than that
animals should acquire inherited tastes for certain kinds of food or
fear of certain foes.
Finally the social instincts, which no doubt were acquired by man as
by the lower animals for the good of the community, will from the
first have given to him some wish to aid his fellows, some feeling
of sympathy, and have compelled him to regard their approbation and
disapprobation. Such impulses will have served him at a very early
period as a rude rule of right and wrong. But as man gradually
advanced in intellectual power, and was enabled to trace the more
remote consequences of his actions; as he aequired sufficient
knowledge to reject baneful customs and superstitions; as he
regarded more and more, not only the welfare, but the happiness of his
fellow-men; as from habit, following on beneficial experience,
instruction and example, his sympathies became more tender and
widely diffused, extending to men of all races, to the imbecile,
maimed, and other useless members of society, and finally to the lower
animals,- so would the standard of his morality rise higher and
higher. And it is admitted by moralists of the derivative school and
by some intuitionists, that the standard of morality has risen since
an early period in the history of man.*
* A writer in the North British Review (July, 1869, p. 531), well
capable of forming a sound judgment, expresses himself strongly in
favour of this conclusion. Mr. Lecky (History of Morals, vol. i., p.
143) seems to a certain extent to coincide therein.
As a struggle may sometimes be seen going on between the various
instincts of the lower animals, it is not surprising that there should
be a struggle in man between his social instincts, with their
derived virtues, and his lower, though momentarily stronger impulses
or desires. This, as Mr. Galton* has remarked, is all the less
surprising, as man has emerged from a state of barbarism within a
comparatively recent period. After having yielded to some temptation
we feel a sense of dissatisfaction, shame, repentance, or remorse,
analogous to the feelings caused by other powerful instincts or
desires, when left unsatisfied or baulked. We compare the weakened
impression of a past temptation with the ever present social
instincts, or with habits, gained in early youth and strengthened
during our whole lives, until they have become almost as strong as
instincts. If with the temptation still before us we do not yield,
it is because either the social instinct or some custom is at the
moment predominant, or because we have learnt that it will appear to
us hereafter the stronger, when compared with the weakened
impression of the temptation, and we realise that its violation
would cause us suffering. Looking to future generations, there is no
cause to fear that the social instincts will grow weaker, and we may
expect that virtuous habits will grow stronger, becoming perhaps fixed
by inheritance. In this case the struggle between our higher and lower
impulses will be less severe, and virtue will be triumphant.
* See his remarkable work on Hereditary Genius, 1869, p. 349. The
Duke of Argyll (Primeval Man, 1869, p. 188) has some good remarks on
the contest in man's nature between right and wrong.
Summary of the last two Chapters.- There can be no doubt that the
difference between the mind of the lowest man and that of the
highest animal is immense. An anthropomorphous ape, if he could take a
dispassionate view of his own case, would admit that though he could
form an artful plan to plunder a garden- though he could use stones
for fighting or for breaking open nuts, yet that the thought of
fashioning a stone into a tool was quite beyond his scope. Still less,
as he would admit, could he follow out a train of metaphysical
reasoning, or solve a mathematical problem, or reflect on God, or
admire a grand natural scene. Some apes, however, would probably
declare that they could and did admire the beauty of the coloured skin
and fur of their partners in marriage. They would admit, that though
they could make other apes understand by cries some of their
perceptions and simpler wants, the notion of expressing definite ideas
by definite sounds had never crossed their minds. They might insist
that they were ready to aid their fellow-apes of the same troop in
many ways, to risk their lives for them, and to take charge of their
orphans; but they would be forced to acknowledge that disinterested
love for all living creatures, the most noble attribute of man, was
quite beyond their comprehension.
Nevertheless the difference in mind between man and the higher
animals, great as it is, certainly is one of degree and not of kind.
We have seen that the senses and intuitions, the various emotions
and faculties, such as love, memory, attention, curiosity,
imitation, reason, &c., of which man boasts, may be found in an
incipient, or even sometimes in a well-developed condition, in the
lower animals. They are also capable of some inherited improvement, as
we see in the domestic dog compared with the wolf or jackal. If it
could be proved that certain high mental powers, such as the formation
of general concepts, self-consciousness, &c., were absolutely peculiar
to man, which seems extremely doubtful, it is not improbable that
these qualities are merely the incidental results of other
highly-advanced intellectual faculties; and these again mainly the
result of the continued use of a perfect language. At what age does
the new-born infant possess the power of abstraction, or become
self-conscious, and reflect on its own existence? We cannot answer;
nor can we answer in regard to the ascending organic scale. The
half-art, half-instinct of language still bears the stamp of its
gradual evolution. The ennobling belief in God is not universal with
man; and the belief in spiritual agencies naturally follows from other
mental powers. The moral sense perhaps affords the best and highest
distinction between man and the lower animals; but I need say
nothing on this head, as I have so lately endeavoured to shew that the
social instincts,- the prime principle of man's moral constitution*
- with the aid of active intellectual powers and the effects of habit,
naturally lead to the golden rule, "As ye would that men should do
to you, do ye to them likewise"; and this lies at the foundation of
morality.
* Marcus Aurelius, Meditations, Bk. V, sect. 55.
In the next chapter I shall make some few remarks on the probable
steps and means by which the several mental and moral faculties of man
have been gradually evolved. That such evolution is at least possible,
ought not to be denied, for we daily see these faculties developing in
every infant; and we may trace a perfect gradation from the mind of an
utter idiot, lower than that of an animal low in the scale, to the
mind of a Newton.
CHAPTER V.
ON THE DEVELOPMENT OF THE INTELLECTUAL AND MORAL FACULTIES.
DURING PRIMEVAL AND CIVILISED TIMES.
THE subjects to be discussed in this chapter are of the highest
interest, but are treated by me in an imperfect and fragmentary
manner. Mr. Wallace, in an admirable paper before referred to,* argues
that man, after he had partially acquired those intellectual and moral
faculties which distinguish him from the lower animals, would have
been but little liable to bodily modifications through natural
selection or any other means. For man is enabled through his mental
faculties "to keep with an unchanged body in harmony with the changing
universe." He has great power of adapting his habits to new conditions
of life. He invents weapons, tools, and various stratagems to
procure food and to defend himself. When he migrates into a colder
climate he uses clothes, builds sheds, and makes fires; and by the aid
of fire cooks food otherwise indigestible. He aids his fellow-men in
many ways, and anticipates future events. Even at a remote period he
practised some division of labour.
* Anthropological Review, May, 1864, p. clviii.
The lower animals, on the other hand, must have their bodily
structure modified in order to survive under greatly changed
conditions. They must be rendered stronger, or acquire more
effective teeth or claws, for defence against new enemies; or they
must be reduced in size, so as to escape detection and danger. When
they migrate into a colder climate, they must become clothed with
thicker fur, or have their constitutions altered. If they fail to be
thus modified, they will cease to exist.
The case, however, is widely different, as Mr. Wallace has with
justice insisted, in relation to the intellectual and moral
faculties of man. These faculties are variable; and we have every
reason to believe that the variations tend to be inherited. Therefore,
if they were formerly of high importance to primeval man and to his
ape-like progenitors, they would have been perfected or advanced
through natural selection. Of the high importance of the
intellectual faculties there can be no doubt, for man mainly owes to
them his predominant position in the world. We can see, that in the
rudest state of society, the individuals who were the most
sagacious, who invented and used the best weapons or traps, and who
were best able to defend themselves, would rear the greatest number of
offspring. The tribes, which included the largest number of men thus
endowed, would increase in number and supplant other tribes. Numbers
depend primarily on the means of subsistence, and this depends
partly on the physical nature of the country, but in a much higher
degree on the arts which are there practised. As a tribe increases and
is victorious, it is often still further increased by the absorption
of other tribes.* The stature and strength of the men of a tribe are
likewise of some importance for its success, and these depend in
part on the nature and amount of the food which can be obtained. In
Europe the men of the Bronze period were supplanted by a race more
powerful, and, judging from their sword-handles, with larger
hands;*(2) but their success was probably still more due to their
superiority in the arts.
* After a time the members of tribes which are absorbed into another
tribe assume, as Sir Henry Maine remarks (Ancient Law, 1861, p.
131), that they are the co-descendants of the same ancestors.
*(2) Morlot, Soc. Vaud. Sc. Nat., 1860, p. 294.
All that we know about savages, or may infer from their traditions
and from old monuments, the history of which is quite forgotten by the
present inhabitants, shew that from the remotest times successful
tribes have supplanted other tribes. Relics of extinct or forgotten
tribes have been discovered throughout the civilised regions of the
earth, on the wild plains of America, and on the isolated islands in
the Pacific Ocean. At the present day civilised nations are everywhere
supplanting barbarous nations, excepting where the climate opposes a
deadly barrier; and they succeed mainly, though not exclusively,
through their arts, which are the products of the intellect. It is,
therefore, highly probable that with mankind the intellectual
faculties have been mainly and gradually perfected through natural
selection; and this conclusion is sufficient for our purpose.
Undoubtedly it would be interesting to trace the development of each
separate faculty from the state in which it exists in the lower
animals to that in which it exists in man; but neither my ability
nor knowledge permits the attempt.
It deserves notice that, as soon as the progenitors of man became
social (and this probably occurred at a very early period), the
principle of imitation, and reason, and experience would have
increased, and much modified the intellectual powers in a way, of
which we see only traces in the lower animals. Apes are much given
to imitation, as are the lowest savages; and the simple fact
previously referred to, that after a time no animal can be caught in
the same place by the same sort of trap, shews that animals learn by
experience, and imitate the caution of others. Now, if some one man in
a tribe, more sagacious than the others, invented a new snare or
weapon, or other means of attack or defence, the plainest
self-interest, without the assistance of much reasoning power, would
prompt the other members to imitate him; and all would thus profit.
The habitual practice of each new art must likewise in some slight
degree strengthen the intellect. If the new invention were an
important one, the tribe would increase in number, spread, and
supplant other tribes. In a tribe thus rendered more numerous there
would always be a rather greater chance of the birth of other superior
and inventive members. If such men left children to inherit their
mental superiority, the chance of the birth of still more ingenious
members would be somewhat better, and in a very small tribe
decidedly better. Even if they left no children, the tribe would still
include their blood-relations; and it has been ascertained by
agriculturists* that by preserving and breeding from the family of
an animal, which when slaughtered was found to be valuable, the
desired character has been obtained.
* I have given instances in my Variation of Animals under
Domestication, vol. ii., p. 196.
Turning now to the social and moral faculties. In order that
primeval men, or the apelike progenitors of man, should become social,
they must have acquired the same instinctive feelings, which impel
other animals to live in a body; and they no doubt exhibited the
same general disposition. They would have felt uneasy when separated
from their comrades, for whom they would have felt some degree of
love; they would have warned each other of danger, and have given
mutual aid in attack or defence. All this implies some degree of
sympathy, fidelity, and courage. Such social qualities, the
paramount importance of which to the lower animals is disputed by no
one, were no doubt acquired by the progenitors of man in a similar
manner, namely, through natural selection, aided by inherited habit.
When two tribes of primeval man, living in the same country, came into
competition, if (other circumstances being equal) the one tribe
included a great number of courageous, sympathetic and faithful
members, who were always ready to warn each other of danger, to aid
and defend each other, this tribe would succeed better and conquer the
other. Let it be borne in mind how all-important in the
never-ceasing wars of savages, fidelity and courage must be. The
advantage which disciplined soldiers have over undisciplined hordes
follows chiefly from the confidence which each man feels in his
comrades. Obedience, as Mr. Bagehot has well shewn,* is of the highest
value, for any form of government is better than none. Selfish and
contentious people will not cohere, and without coherence nothing
can be effected. A tribe rich in the above qualities would spread
and be victorious over other tribes: but in the course of time it
would, judging from all past history, be in its turn overcome by
some other tribe still more highly endowed. Thus the social and
moral qualities would tend slowly to advance and be diffused
throughout the world.
* See a remarkable series of articles on "Physics and Politics,"
in the Fortnightly Review, Nov., 1867; April 1, 1868; July 1, 1869,
since separately published.
But it may be asked, how within the limits of the same tribe did a
large number of members first become endowed with these social and
moral qualities, and how was the standard of excellence raised? It
is extremely doubtful whether the offspring of the more sympathetic
and benevolent parents, or of those who were the most faithful to
their comrades, would be reared in greater numbers than the children
of selfish and treacherous parents belonging to the same tribe. He who
was ready to sacrifice his life, as many a savage has been, rather
than betray his comrades, would often leave no offspring to inherit
his noble nature. The bravest men, who were always willing to come
to the front in war, and who freely risked their lives for others,
would on an average perish in larger numbers than other men.
Therefore, it hardly seems probable that the number of men gifted with
such virtues, or that the standard of their excellence, could be
increased through natural selection, that is, by the survival of the
fittest; for we are not here speaking of one tribe being victorious
over another.
Although the circumstances, leading to an increase in the number
of those thus endowed within the same tribe, are too complex to be
clearly followed out, we can trace some of the probable steps. In
the first place, as the reasoning powers and foresight of the
members became improved, each man would soon learn that if he aided
his fellow-men, he would commonly receive aid in return. From this low
motive he might acquire the habit of aiding his fellows; and the habit
of performing benevolent actions certainly strengthens the feeling
of sympathy which gives the first impulse to benevolent actions.
Habits, moreover, followed during many generations probably tend to be
inherited.
But another and much more powerful stimulus to the development of
the social virtues, is afforded by the praise and the blame of our
fellow-men. To the instinct of sympathy, as we have already seen, it
is primarily due, that we habitually bestow both praises and blame
on others, whilst we love the former and dread the latter when applied
to ourselves; and this instinct no doubt was originally acquired, like
all the other social instincts, through natural selection. At how
early a period the progenitors of man in the course of their
development, became capable of feeling and being impelled by, the
praise or blame of their fellow-creatures, we cannot of course say.
But it appears that even dogs appreciate encouragement, praise, and
blame. The rudest savages feel the sentiment of glory, as they clearly
show by preserving the trophies of their prowess, by their habit of
excessive boasting, and even by the extreme care which they take of
their personal appearance and decorations; for unless they regarded
the opinion of their comrades, such habits would be senseless.
They certainly feel shame at the breach of some of their lesser
rules, and apparently remorse, as shewn by the case of the
Australian who grew thin and could not rest from having delayed to
murder some other woman, so as to propitiate his dead wife's spirit.
Though I have not met with any other recorded case, it is scarcely
credible that a savage, who will sacrifice his life rather than betray
his tribe, or one who will deliver himself up as a prisoner rather
than break his parole,* would not feel remorse in his inmost soul,
if he had failed in a duty, which he held sacred.
* Mr. Wallace gives cases in his Contributions to the Theory of
Natural Selection, 1870, p. 354.
We may therefore conclude that primeval man, at a very remote
period, was influenced by the praise and blame of his fellows. It is
obvious, that the members of the same tribe would approve of conduct
which appeared to them to be for the general good, and would reprobate
that which appeared evil. To do good unto others- to do unto others as
ye would they should do unto you- is the foundation-stone of morality.
It is, therefore, hardly possible to exaggerate the importance
during rude times of the love of praise and the dread of blame. A
man who was not impelled by any deep, instinctive feeling, to
sacrifice his life for the good of others, yet was roused to such
actions by a sense of glory, would by his example excite the same wish
for glory in other men, and would strengthen by exercise the noble
feeling of admiration. He might thus do far more good to his tribe
than by begetting offspring with a tendency to inherit his own high
character.
With increased experience and reason, man perceives the more
remote consequences of his actions, and the self-regarding virtues,
such as temperance, chastity, &c., which during early times are, as we
have before seen, utterly disregarded, come to be highly esteemed or
even held sacred. I need not, however, repeat what I have said on this
head in the fourth chapter. Ultimately our moral sense or conscience
becomes a highly complex sentiment- originating in the social
instincts, largely guided by the approbation of our fellow-men,
ruled by reason, self-interest, and in later times by deep religious
feelings, and confirmed by instruction and habit.
It must not be forgotten that although a high standard of morality
gives but a slight or no advantage to each individual man and his
children over the other men of the same tribe, yet that an increase in
the number of well-endowed men and an advancement in the standard of
morality will certainly give an immense advantage to one tribe over
another. A tribe including many members who, from possessing in a high
degree the spirit of patriotism, fidelity, obedience, courage, and
sympathy, were always ready to aid one another, and to sacrifice
themselves for the common good, would be victorious over most other
tribes; and this would be natural selection. At all times throughout
the world tribes have supplanted other tribes; and as morality is
one important element in their success, the standard of morality and
the number of well-endowed men will thus everywhere tend to rise and
increase.
It is, however, very difficult to form any judgment why one
particular tribe and not another has been successful and has risen
in the scale of civilisation. Many savages are in the same condition
as when first discovered several centuries ago. As Mr. Bagehot has
remarked, we are apt to look at the progress as normal in human
society; but history refutes this. The ancients did not even entertain
the idea, nor do the Oriental nations at the present day. According to
another high authority, Sir Henry Maine, "The greatest part of mankind
has never shewn a particle of desire that its civil institutions
should be improved."* Progress seems to depend on many concurrent
favourable conditions, far too complex to be followed out. But it
has often been remarked, that a cool climate, from leading to industry
and to the various arts, has been highly favourable thereto. The
Esquimaux, pressed by hard necessity, have succeeded in many ingenious
inventions, but their climate has been too severe for continued
progress. Nomadic habits, whether over wide plains, or through the
dense forests of the tropics, or along the shores of the sea, have
in every case been highly detrimental. Whilst observing the
barbarous inhabitants of Tierra del Fuego, it struck me that the
possession of some property, a fixed abode, and the union of many
families under a chief, were the indispensable requisites for
civilisation. Such habits almost necessitate the cultivation of the
ground and the first steps in cultivation would probably result, as
I have elsewhere shewn,*(2) from some such accident as the seeds of
a fruit-tree falling on a heap of refuse, and producing an unusually
fine variety. The problem, however, of the first advance of savages
towards civilisation is at present much too difficult to be solved.
* Ancient Law, 1861, p. 22. For Mr. Bagehot's remarks, Fortnightly
Review, April 1, 1868, p. 452.
*(2) The Variation of Animals and Plants under Domestication, vol.
i., p. 309.
Natural Selection as affecting Civilised Nations.- I have hitherto
only considered the advancement of man from a semi-human condition
to that of the modern savage. But some remarks on the action of
natural selection on civilised nations may be worth adding. This
subject has been ably discussed by Mr. W. R. Greg,* and previously
by Mr. Wallace and Mr. Galton.*(2) Most of my remarks are taken from
these three authors. With savages, the weak in body or mind are soon
eliminated; and those that survive commonly exhibit a vigorous state
of health. We civilised men, on the other hand, do our utmost to check
the process of elimination; we build asylums for the imbecile, the
maimed, and the sick; we institute poor-laws; and our medical men
exert their utmost skill to save the life of every one to the last
moment. There is reason to believe that vaccination has preserved
thousands, who from a weak constitution would formerly have
succumbed to small-pox. Thus the weak members of civilised societies
propagate their kind. No one who has attended to the breeding of
domestic animals will doubt that this must be highly injurious to
the race of man. It is surprising how soon a want of care, or care
wrongly directed, leads to the degeneration of a domestic race; but
excepting in the case of man himself, hardly any one is so ignorant as
to allow his worst animals to breed.
* Fraser's Magazine, Sept., 1868, p. 353. This article seems to have
struck many persons, and has given rise to two remarkable essays and a
rejoinder in the Spectator, Oct. 3 and 17, 1868. It has also been
discussed in the Quarterly Journal of Science, 1869, p. 152, and by
Mr. Lawson Tait in the Dublin Quarterly Journal of Medical Science,
Feb., 1869, and by Mr. E. Ray Lankester in his Comparative
Longevity, 1870, p. 128. Similar views appeared previously in the
Australasian, July 13, 1867. I have borrowed ideas from several of
these writers.
*(2) For Mr. Wallace, see Anthropological Review, as before cited.
Mr. Galton in Macmillan's Magazine, Aug., 1865, p. 318; also his great
work, Hereditary Genius, 1870.
The aid which we feel impelled to give to the helpless is mainly
an incidental result of the instinct of sympathy, which was originally
acquired as part of the social instincts, but subsequently rendered,
in the manner previously indicated, more tender and more widely
diffused. Nor could we check our sympathy, even at the urging of
hard reason, without deterioration in the noblest part of our
nature. The surgeon may harden himself whilst performing an operation,
for he knows that he is acting for the good of his patient; but if
we were intentionally to neglect the weak and helpless, it could
only be for a contingent benefit, with an overwhelming present evil.
We must therefore bear the undoubtedly bad effects of the weak
surviving and propagating their kind; but there appears to be at least
one check in steady action, namely that the weaker and inferior
members of society do not marry so freely as the sound; and this check
might be indefinitely increased by the weak in body or mind refraining
from marriage, though this is more to be hoped for than expected.
In every country in which a large standing army is kept up, the
finest young men are taken by the conscription or are enlisted. They
are thus exposed to early death during war, are often tempted into
vice, and are prevented from marrying during the prime of life. On the
other hand the shorter and feebler men, with poor constitutions, are
left at home, and consequently have a much better chance of marrying
and propagating their kind.*
* Prof. H. Fick (Einfluss der Naturwissenschaft auf das Recht, June,
1872) has some good remarks on this head, and on other such points.
Man accumulates property and bequeaths it to his children, so that
the children of the rich have an advantage over the poor in the race
for success, independently of bodily or mental superiority. On the
other hand, the children of parents who are short-lived, and are
therefore on an average deficient in health and vigour, come into
their property sooner than other children, and will be likely to marry
earlier, and leave a larger number of offspring to inherit their
inferior constitutions. But the inheritance of property by itself is
very far from an evil; for without the accumulation of capital the
arts could not progress; and it is chiefly through their power that
the civilised races have extended, and are now everywhere extending
their range, so as to take the place of the lower races. Nor does
the moderate accumulation of wealth interfere with the process of
selection. When a poor man becomes moderately rich, his children enter
trades or professions in which there is struggle enough, so that the
able in body and mind succeed best. The presence of a body of
well-instructed men, who have not to labour for their daily bread,
is important to a degree which cannot be over-estimated; as all high
intellectual work is carried on by them, and on such work, material
progress of all kinds mainly depends, not to mention other and
higher advantages. No doubt wealth when very great tends to convert
men into useless drones, but their number is never large; and some
degree of elimination here occurs, for we daily see rich men, who
happen to be fools or profligate, squandering away their wealth.
Primogeniture with entailed estates is a more direct evil, though it
may formerly have been a great advantage by the creation of a dominant
class, and any government is better than none. Most eldest sons,
though they may be weak in body or mind, marry, whilst the younger
sons, however superior in these respects, do not so generally marry.
Nor can worthless eldest sons with entailed estates squander their
wealth. But here, as elsewhere, the relations of civilised life are so
complex that some compensatory checks intervene. The men who are
rich through primogeniture are able to select generation after
generation the more beautiful and charming women; and these must
generally be healthy in body and active in mind. The evil
consequences, such as they may be, of the continued preservation of
the same line of descent, without any selection, are checked by men of
rank always wishing to increase their wealth and power; and this
they effect by marrying heiresses. But the daughters of parents who
have produced single children, are themselves, as Mr. Galton* has
shewn, apt to be sterile; and thus noble families are continually
cut off in the direct line, and their wealth flows into some side
channel; but unfortunately this channel is not determined by
superiority of any kind.
* Hereditary Genius, 1870, pp. 132-140.
Although civilisation thus checks in many ways the action of natural
selection, it apparently favours the better development of the body,
by means of good food and the freedom from occasional hardships.
This may be inferred from civilised men having been found, wherever
compared, to be physically stronger than savages.* They appear also to
have equal powers of endurance, as has been proved in many adventurous
expeditions. Even the great luxury of the rich can be but little
detrimental; for the expectation of life of our aristocracy, at all
ages and of both sexes, is very little inferior to that of healthy
English lives in the lower classes.*(2)
* Quatrefages, Revue des Cours Scientifiques 1867-68, p. 659.
*(2) See the fifth and sixth columns compiled from good authorities,
in the table given in Mr. E. R. Lankester's Comparative Longevity,
1870, p. 115.
We will now look to the intellectual faculties. If in each grade
of society the members were divided into two equal bodies, the one
including the intellectually superior and the other the inferior,
there can be little doubt that the former would succeed best in all
occupations, and rear a greater number of children. Even in the lowest
walks of life, skill and ability must be of some advantage; though
in many occupations, owing to the great division of labour, a very
small one. Hence in civilised nations there will be some tendency to
an increase both in the number and in the standard of the
intellectually able. But I do not wish to assert that this tendency
may not be more than counterbalanced in other ways, as by the
multiplication of the reckless and improvident; but even to such as
these, ability must be some advantage.
It has often been objected to views like the foregoing, that the
most eminent men who have ever lived have left no offspring to inherit
their great intellect. Mr. Galton says, "I regret I am unable to solve
the simple question whether, and how far, men and women who are
prodigies of genius are infertile. I have, however, shewn that men
of eminence are by no means so."* Great lawgivers, the founders of
beneficent religions, great philosophers and discoverers in science,
aid the progress of mankind in a far higher degree by their works than
by leaving a numerous progeny. In the case of corporeal structures, it
is the selection of the slightly better-endowed and the elimination of
the slightly less well-endowed individuals, and not the preservation
of strongly-marked and rare anomalies, that leads to the advancement
of a species.*(2) So it will be with the intellectual faculties, since
the somewhat abler men in each grade of society succeed rather
better than the less able, and consequently increase in number, if not
otherwise prevented. When in any nation the standard of intellect
and the number of intellectual men have increased, we may expect
from the law of the deviation from an average, that prodigies of
genius will, as shewn by Mr. Galton, appear somewhat more frequently
than before.
* Hereditary Genius, 1870, p. 330.
*(2) Origin of Species.(OOS)
In regard to the moral qualities, some elimination of the worst
dispositions is always in progress even in the most civilised nations.
Malefactors are executed, or imprisoned for long periods, so that they
cannot freely transmit their bad qualities. Melancholic and insane
persons are confined, or commit suicide. Violent and quarrelsome men
often come to a bloody end. The restless who will not follow any
steady occupation- and this relic of barbarism is a great check to
civilisation* - emigrate to newly-settled countries; where they
prove useful pioneers. Intemperance is so highly destructive, that the
expectation of life of the intemperate, at the age of thirty for
instance, is only 13.8 years; whilst for the rural labourers of
England at the same age it is 40.59 years.*(2) Profligate women bear
few children, and profligate men rarely marry; both suffer from
disease. In the breeding of domestic animals, the elimination of those
individuals, though few in number, which are in any marked manner
inferior, is by no means an unimportant element towards success.
This especially holds good with injurious characters which tend to
reappear through reversion, such as blackness in sheep; and with
mankind some of the worst dispositions, which occasionally without any
assignable cause make their appearance in families, may perhaps be
reversions to a savage state, from which we are not removed by very
many generations. This view seems indeed recognised in the common
expression that such men are the black sheep of the family.
* Hereditary Genius, 1870, p. 347.
*(2) E Ray Lankester, Comparative Longevity, 1870, p. 115. The table
of the intemperate is from Neison's Vital Statistics. In regard to
profligacy, see Dr. Farr, "Influence of Marriage on Mortality," Nat.
Assoc. for the Promotion of Social Science, 1858.
With civilised nations, as far as an advanced standard of
morality, and an increased number of fairly good men are concerned,
natural selection apparently effects but little; though the
fundamental social instincts were originally thus gained. But I have
already said enough, whilst treating of the lower races, on the causes
which lead to the advance of morality, namely, the approbation of
our fellow-men- the strengthening of our sympathies by habit-
example and imitation- reason- experience, and even self-interest-
instruction during youth, and religious feelings.
A most important obstacle in civilised countries to an increase in
the number of men of a superior class has been strongly insisted on by
Mr. Greg and Mr. Galton,* namely, the fact that the very poor and
reckless, who are often degraded by vice, almost invariably marry
early, whilst the careful and frugal, who are generally otherwise
virtuous, marry late in life, so that they may be able to support
themselves and their children in comfort. Those who marry early
produce within a given period not only a greater number of
generations, but, as shewn by Dr. Duncan,*(2) they produce many more
children. The children, moreover, that are borne by mothers during the
prime of life are heavier and larger, and therefore probably more
vigorous, than those born at other periods. Thus the reckless,
degraded, and often vicious members of society, tend to increase at
a quicker rate than the provident and generally virtuous members. Or
as Mr. Greg puts the case: "The careless, squalid, unaspiring Irishman
multiplies like rabbits: the frugal, foreseeing, self-respecting,
ambitious Scot, stern in his morality, spiritual in his faith,
sagacious and disciplined in his intelligence, passes his best years
in struggle and in celibacy, marries late, and leaves few behind
him. Given a land originally peopled by a thousand Saxons and a
thousand Celts- and in a dozen generations five-sixths of the
population would be Celts, but five-sixths of the property, of the
power, of the intellect, would belong to the one-sixth of Saxons
that remained. In the eternal 'struggle for existence,' it would be
the inferior and less favoured race that had prevailed- and
prevailed by virtue not of its good qualities but of its faults."
* Fraser's Magazine, Sept., 1868, p. 353. Macmillan's Magazine,
Aug., 1865, p. 318. The Rev. F. W. Farrar (Fraser's Magazine, Aug.,
1870, p. 264) takes a different view.
*(2) "On the Laws of the Fertility of Women," in Transactions of the
Royal Society, Edinburgh, vol. xxiv., p. 287; now published separately
under the title of Fecundity, Fertility, and Sterility, 1871. See,
also, Mr. Galton, Hereditary Genius pp. 352-357, for observations to
the above effect.
There are, however, some checks to this downward tendency. We have
seen that the intemperate suffer from a high rate of mortality, and
the extremely profligate leave few offspring. The poorest classes
crowd into towns, and it has been proved by Dr. Stark from the
statistics of ten years in Scotland,* that at all ages the
death-rate is higher in towns than in rural districts, "and during the
first five years of life the town death-rate is almost exactly
double that of the rural districts." As these returns include both the
rich and the poor, no doubt more than twice the number of births would
be requisite to keep up the number of the very poor inhabitants in the
towns, relatively to those in the country. With women, marriage at too
early an age is highly injurious; for it has been found in France
that, "Twice as many wives under twenty die in the year, as died out
of the same number of the unmarried." The mortality, also, of husbands
under twenty is "excessively high,"*(2) but what the cause of this may
be, seems doubtful. Lastly, if the men who prudently delay marrying
until they can bring up their families in comfort, were to select,
as they often do, women in the prime of life, the rate of increase
in the better class would be only slightly lessened.
* Tenth Annual Report of Births, Deaths, &c., in Scotland, 1867,
p. xxix.
*(2) These quotations are taken from our highest authority on such
questions, namely, Dr. Farr, in his paper "On the Influence of
Marriage on the Mortality of the French People," read before the
Nat. Assoc. for the Promotion of Social Science, 1858.
It was established from an enormous body of statistics, taken during
1853, that the unmarried men throughout France, between the ages of
twenty and eighty, die in a much larger proportion than the married:
for instance, out of every 1000 unmarried men, between the ages of
twenty and thirty, 11.3 annually died, whilst of the married, only 6.5
died.* A similar law was proved to hold good, during the years 1863
and 1864, with the entire population above the age of twenty in
Scotland: for instance, out of every 1000 unmarried men, between the
ages of twenty and thirty, 14.97 annually died, whilst of the
married only 7.24 died, that is less than half.*(2) Dr. Stark
remarks on this, "Bachelorhood is more destructive to life than the
most unwholesome trades, or than residence in an unwholesome house
or district where there has never been the most distant attempt at
sanitary improvement." He considers that the lessened mortality is the
direct result of "marriage, and the more regular domestic habits which
attend that state." He admits, however, that the intemperate,
profligate, and criminal classes, whose duration of life is low, do
not commonly marry; and it must likewise be admitted that men with a
weak constitution, ill health, or any great infirmity in body or mind,
will often not wish to marry, or will be rejected. Dr. Stark seems
to have come to the conclusion that marriage in itself is a main cause
of prolonged life, from finding that aged married men still have a
considerable advantage in this respect over the unmarried of the
same advanced age; but every one must have known instances of men, who
with weak health during youth did not marry, and yet have survived
to old age, though remaining weak, and therefore with a lessened
chance of life or of marrying. There is another remarkable
circumstance which seems to support Dr. Stark's conclusion, namely,
that widows and widowers in France suffer in comparison with the
married a very heavy rate of mortality; but Dr. Farr attributes this
to the poverty and evil habits consequent on the disruption of the
family, and to grief. On the whole we may conclude with Dr. Farr
that the lesser mortality of married than of unmarried men, which
seems to be a general law, "is mainly due to the constant
elimination of imperfect types, and to the skilful selection of the
finest individuals out of each successive generation"; the selection
relating only to the marriage state, and acting on all corporeal,
intellectual, and moral qualities.*(3) We may, therefore, infer that
sound and good men who out of prudence remain for a time unmarried, do
not suffer a high rate of mortality.
* Dr. Farr, ibid. The quotations given below are extracted from
the same striking paper.
*(2) I have taken the mean of the quinquennial means, given in the
Tenth Annual Report of Births, Deaths, &c., in Scotland, 1867. The
quotation from Dr. Stark is copied from an article in the Daily
News, Oct. 17, 1868. which Dr. Farr considers very carefully written.
*(3) Dr. Duncan remarks (Fecundity, Fertility, &c., 1871, p. 334) on
this subject: "At every age the healthy and beautiful go over from the
unmarried side to the married, leaving the unmarried columns crowded
with the sickly and unfortunate."
If the various checks specified in the two last paragraphs, and
perhaps others as yet unknown, do not prevent the reckless, the
vicious and otherwise inferior members of society from increasing at a
quicker rate than the better class of men, the nation will retrograde,
as has too often occurred in the history of the world. We must
remember that progress is no invariable rule. It is very difficult
to say why one civilised nation rises, becomes more powerful, and
spreads more widely, than another; or why the same nation progresses
more quickly at one time than at another. We can only say that it
depends on an increase in the actual number of the population, on
the number of men endowed with high intellectual and moral
faculties, as well as on their standard of excellence. Corporeal
structure appears to have little influence, except so far as vigour of
body leads to vigour of mind.
It has been urged by several writers that as high intellectual
powers are advantageous to a nation, the old Greeks, who stood some
grades higher in intellect than any race that has ever existed,*
ought, if the power of natural selection were real, to have risen
still higher in the scale, increased in number, and stocked the
whole of Europe. Here we have the tacit assumption, so often made with
respect to corporeal structures, that there is some innate tendency
towards continued development in mind and body. But development of all
kinds depends on many concurrent favourable circumstances. Natural
selection acts only tentatively. Individuals and races may have
acquired certain indisputable advantages, and yet have perished from
failing in other characters. The Greeks may have retrograded from a
want of coherence between the many small states, from the small size
of their whole country, from the practice of slavery, or from
extreme sensuality; for they did not succumb until "they were
enervated and corrupt to the very core."*(2) The western nations of
Europe, who now so immeasurably surpass their former savage
progenitors, and stand at the summit of civilisation, owe little or
none of their superiority to direct inheritance from the old Greeks,
though they owe much to the written works of that wonderful people.
* See the ingenious and original argument on this subject by Mr.
Galton, Hereditary Genius, pp. 340-342.
*(2) Mr. Greg, Fraser's Magazine, Sept., 1868, p. 357.
Who can positively say why the Spanish nation, so dominant at one
time, has been distanced in the race? The awakening of the nations
of Europe from the dark ages is a still more perplexing problem. At
that early period, as Mr. Galton has remarked, almost all the men of a
gentle nature, those given to meditation or culture of the mind, had
no refuge except in the bosom of a Church which demanded celibacy;*
and this could hardly fail to have had a deteriorating influence on
each successive generation. During this same period the Holy
Inquisition selected with extreme care the freest and boldest men in
order to burn or imprison them. In Spain alone some of the best men-
those who doubted and questioned, and without doubting there can be no
progress- were eliminated during three centuries at the rate of a
thousand a year. The evil which the Catholic Church has thus
effected is incalculable, though no doubt counterbalanced to a
certain, perhaps to a large, extent in other ways; nevertheless,
Europe has progressed at an unparalleled rate.
* Hereditary Genius, 1870, pp. 357-359. The Rev. F. W. Farrar
(Fraser's Magazine, Aug., 1870, p. 257) advances arguments on the
other side. Sir C. Lyell had already (Principles of Geology, vol. ii.,
1868, p. 489), in a striking passage, called attention to the evil
influence of the Holy Inquisition in having, through selection,
lowered the general standard of intelligence in Europe.
The remarkable success of the English as colonists, compared to
other European nations, has been ascribed to their "daring and
persistent energy"; a result which is well illustrated by comparing
the progress of the Canadians of English and French extraction; but
who can say how the English gained their energy? There is apparently
much truth in the belief that the wonderful progress of the United
States, as well as the character of the people, are the results of
natural selection; for the more energetic, restless, and courageous
men from all parts of Europe have emigrated during the last ten or
twelve generations to that great country, and have there succeeded
best.* Looking to the distant future, I do not think that the Rev. Mr.
Zincke takes an exaggerated view when he says:*(2) "All other series
of events- as that which resulted in the culture of mind in Greece,
and that which resulted in the empire of Rome- only appear to have
purpose and value when viewed in connection with, or rather as
subsidiary to... the great stream of Anglo-Saxon emigration to the
west." Obscure as is the problem of the advance of civilisation, we
can at least see that a nation which produced during a lengthened
period the greatest number of highly intellectual, energetic, brave,
patriotic, and benevolent men, would generally prevail over less
favoured nations.
* Mr. Galton, Macmillan's Magazine, August, 1865, p. 325. See
also, Nature, "On Darwinism and National Life," Dec., 1869, p. 184.
*(2) Last Winter in the United States, 1868, p. 29.
Natural selection follows from the struggle for existence; and
this from a rapid rate of increase. It is impossible not to regret
bitterly, but whether wisely is another question, the rate at which
man tends to increase; for this leads in barbarous tribes to
infanticide and many other evils, and in civilised nations to abject
poverty, celibacy, and to the late marriages of the prudent. But as
man suffers from the same physical evils as the lower animals, he
has no right to expect an immunity from the evils consequent on the
struggle for existence. Had he not been subjected during primeval
times to natural selection, assuredly he would never have attained
to his present rank. Since we see in many parts of the world
enormous areas of the most fertile land capable of supporting numerous
happy homes, but peopled only by a few wandering savages, it might
be argued that the struggle for existence had not been sufficiently
severe to force man upwards to his highest standard. Judging from
all that we know of man and the lower animals, there has always been
sufficient variability in their intellectual and moral faculties,
for a steady advance through natural selection. No doubt such
advance demands many favourable concurrent circumstances; but it may
well be doubted whether the most favourable would have sufficed, had
not the rate of increase been rapid, and the consequent struggle for
existence extremely severe. It even appears from what we see, for
instance, in parts of S. America, that a people which may be called
civilised, such as the Spanish settlers, is liable to become
indolent and to retrograde, when the conditions of life are very easy.
With highly civilised nations continued progress depends in a
subordinate degree on natural selection; for such nations do not
supplant and exterminate one another as do savage tribes. Nevertheless
the more intelligent members within the same community will succeed
better in the long run than the inferior, and leave a more numerous
progeny, and this is a form of natural selection. The more efficient
causes of progress seem to consist of a good education during youth
whilst the brain is impressible, and of a high standard of excellence,
inculcated by the ablest and best men, embodied in the laws, customs
and traditions of the nation, and enforced by public opinion. It
should, however, be borne in mind, that the enforcement of public
opinion depends on our appreciation of the approbation and
disapprobation of others; and this appreciation is founded on our
sympathy, which it can hardly be doubted was originally developed
through natural selection as one of the most important elements of the
social instincts.*
* I am much indebted to Mr. John Morley for some good criticisms
on this subject: see, also Broca, "Les Selections," Revue
d'Anthropologie, 1872.
On the evidence that all civilised nations were once barbarous.- The
present subject has been treated in so full and admirable a manner
by Sir J. Lubbock,* Mr. Tylor, Mr. M'Lennan, and others, that I need
here give only the briefest summary of their results. The arguments
recently advanced by the Duke of Argyll*(2) and formerly by Archbishop
Whately, in favour of the belief that man came into the world as a
civilised being, and that all savages have since undergone
degradation, seem to me weak in comparison with those advanced on
the other side. Many nations, no doubt, have fallen away in
civilisation, and some may have lapsed into utter barbarism, though on
this latter head I have met with no evidence. The Fuegians were
probably compelled by other conquering hordes to settle in their
inhospitable country, and they may have become in consequence somewhat
more degraded; but it would be difficult to prove that they have
fallen much below the Botocudos, who inhabit the finest parts of
Brazil.
* "On the Origin of Civilisation," Proceedings of the Ethnological
Society, Nov. 26, 1867.
*(2) Primeval Man, 1869.
The evidence that all civilised nations are the descendants of
barbarians, consists, on the one side, of clear traces of their former
low condition in still-existing customs, beliefs, language, &c.; and
on the other side, of proofs that savages are independently able to
raise themselves a few steps in the scale of civilisation, and have
actually thus risen. The evidence on the first head is extremely
curious, but cannot be here given: I refer to such cases as that of
the art of enumeration, which, as Mr. Tylor clearly shews by reference
to the words still used in some places, originated in counting the
fingers, first of one hand and then of the other, and lastly of the
toes. We have traces of this in our own decimal system, and in the
Roman numerals, where, after the V, which is supposed to be an
abbreviated picture of a human hand, we pass on to VI, &c., when the
other hand no doubt was used. So again, "When we speak of
three-score and ten, we are counting by the vigesimal system, each
score thus ideally made, standing for 20- for 'one man' as a Mexican
or Carib would put it."* According to a large and increasing school of
philologists, every language bears the marks of its slow and gradual
evolution. So it is with the art of writing, for letters are rudiments
of pictorial representations. It is hardly possible to read Mr.
M'Lennan's work*(2) and not admit that almost all civilised nations
still retain traces of such rude habits as the forcible capture of
wives. What ancient nation, as the same author asks, can be named that
was originally monogamous? The primitive idea of justice, as shewn
by the law of battle and other customs of which vestiges still remain,
was likewise most rude. Many existing superstitions are the remnants
of former false religious beliefs. The highest form of religion- the
grand idea of God hating sin and loving righteousness- was unknown
during primeval times.
* Royal Institution of Great Britain, March 15, 1867. Also,
Researches into the Early History of Mankind, 1865.
*(2) Primitive Marriage, 1865. See, likewise, an excellent
article, evidently by the same author, in the North British Review,
July, 1869. Also, Mr. L. H. Morgan, "A Conjectural Solution of the
Origin of the Class, System of Relationship," in Proc. American
Acad. of Sciences, vol. vii., Feb., 1868. Prof. Schaaffhausen
(Anthropolog. Review, Oct., 1869, p. 373) remarks on "the vestiges
of human sacrifices found both in Homer and the Old Testament."
Turning to the other kind of evidence: Sir J. Lubbock has shewn that
some savages have recently improved a little in some of their
simpler arts. From the extremely curious account which he gives of the
weapons, tools, and arts, in use amongst savages in various parts of
the world, it cannot be doubted that these have nearly all been
independent discoveries, excepting perhaps the art of making fire.*
The Australian boomerang is a good instance of one such independent
discovery. The Tahitians when first visited had advanced in many
respects beyond the inhabitants of most of the other Polynesian
islands. There are no just grounds for the belief that the high
culture of the native Peruvians and Mexicans was derived from
abroad;*(2) many native plants were there cultivated, and a few native
animals domesticated. We should bear in mind that, judging from the
small influence of most missionaries, a wandering crew from some
semi-civilised land, if washed to the shores of America, would not
have produced any marked effect on the natives, unless they had
already become somewhat advanced. Looking to a very remote period in
the history of the world, we find, to use Sir J. Lubbock's
well-known terms, a paleolithic and neolithic period; and no one
will pretend that the art of grinding rough flint tools was a borrowed
one. In all parts of Europe, as far east as Greece, in Palestine,
India, Japan, New Zealand, and Africa, including Egypt, flint tools
have been discovered in abundance; and of their use the existing
inhabitants retain no tradition. There is also indirect evidence of
their former use by the Chinese and ancient Jews. Hence there can
hardly be a doubt that the inhabitants of these countries, which
include nearly the whole civilised world, were once in a barbarous
condition. To believe that man was aboriginally civilised and then
suffered utter degradation in so many regions, is to take a pitiably
low view of human nature. It is apparently a truer and more cheerful
view that progress has been much more general than retrogression; that
man has risen, though by slow and interrupted steps, from a lowly
condition to the highest standard as yet attained by him in knowledge,
morals and religion.
* Sir J. Lubbock, Prehistoric Times, 2nd ed., 1869, chaps. xv. and
xvi. et passim. See also the excellent 9th chapter in Tylor's Early
History of Mankind, 2nd ed., 1870.
*(2) Dr. F. Muller has made some good remarks to this effect in
the Reise der Novara: Anthropolog. Theil, Abtheil. iii., 1868, s. 127.
CHAPTER VI.
ON THE AFFINITIES AND GENEALOGY OF MAN.
EVEN if it be granted that the difference between man and his
nearest allies is as great in corporeal structure as some
naturalists maintain, and although we must grant that the difference
between them is immense in mental power, yet the facts given in the
earlier chapters appear to declare, in the plainest manner, that man
is descended from some lower form, notwithstanding that
connecting-links have not hitherto been discovered.
Man is liable to numerous, slight, and diversified variations, which
are induced by the same general causes, are governed and transmitted
in accordance with the same general laws, as in the lower animals. Man
has multiplied so rapidly, that he has necessarily been exposed to
struggle for existence, and consequently to natural selection. He
has given rise to many races, some of which differ so much from each
other, that they have often been ranked by naturalists as distinct
species. His body is constructed on the same homological plan as
that of other mammals. He passes through the same phases of
embryological development. He retains many rudimentary and useless
structures, which no doubt were once serviceable. Characters
occasionally make their re-appearance in him, which we have reason
to believe were possessed by his early progenitors. If the origin of
man had been wholly different from that of all other animals, these
various appearances would be mere empty deceptions; but such an
admission is incredible. These appearances, on the other hand, are
intelligible, at least to a large extent, if man is the
co-descendant with other mammals of some unknown and lower form.
Some naturalists, from being deeply impressed with the mental and
spiritual powers of man, have divided the whole organic world into
three kingdoms, the Human, the Animal, and the Vegetable, thus
giving to man a separate kingdom.* Spiritual powers cannot be compared
or classed by the naturalist: but he may endeavour to shew, as I
have done, that the mental faculties of man and the lower animals do
not differ in kind, although immensely in degree. A difference in
degree, however great, does not justify us in placing man in a
distinct kingdom, as will perhaps be best illustrated by comparing the
mental powers of two insects, namely, a coccus or scale-insect and
an ant, which undoubtedly belong to the same class. The difference
is here greater than, though of a somewhat different kind from, that
between man and the highest mammal. The female coccus, whilst young,
attaches itself by its proboscis to a plant; sucks the sap, but
never moves again; is fertilised and lays eggs; and this is its
whole history. On the other hand, to describe the habits and mental
powers of worker-ants, would require, as Pierre Huber has shewn, a
large volume; I may, however, briefly specify a few points. Ants
certainly communicate information to each other, and several unite for
the same work, or for games of play. They recognise their
fellow-ants after months of absence, and feel sympathy for each other.
They build great edifices, keep them clean, close the doors in the
evening, and post sentries. They make roads as well as tunnels under
rivers, and temporary bridges over them, by clinging together. They
collect food for the community, and when an object, too large for
entrance, is brought to the nest, they enlarge the door, and
afterwards build it up again. They store up seeds, of which they
prevent the germination, and which, if damp, are brought up to the
surface to dry. They keep aphides and other insects as milch-cows.
They go out to battle in regular bands, and freely sacrifice their
lives for the common weal. They emigrate according to a preconcerted
plan. They capture slaves. They move the eggs of their aphides, as
well as their own eggs and cocoons, into warm parts of the nest, in
order that they may be quickly hatched; and endless similar facts
could be given.*(2) On the whole, the difference in mental power
between an ant and a coccus is immense; yet no one has ever dreamed of
placing these insects in distinct classes, much less in distinct
kingdoms. No doubt the difference is bridged over by other insects;
and this is not the case with man and the higher apes. But we have
every reason to believe that the breaks in the series are simply the
results of many forms having become extinct.
* Isidore Geoffroy St-Hilaire gives a detailed account of the
position assigned to man by various naturalists in their
classifications: Hist. Nat. Gen. tom. ii., 1859, pp. 170-189.
*(2) Some of the most interesting facts ever published on the habits
of ants are given by Mr. Belt, in his The Naturalist in Nicaragua,
1874. See also Mr. Moggridge's admirable work, Harvesting Ants, &c.,
1873, also "L'Instinct chez les insectes," by M. George Pouchet, Revue
des Deux Mondes, Feb., 1870, p. 682.
Professor Owen, relying chiefly on the structure of the brain, has
divided the mammalian series into four sub-classes. One of these he
devotes to man; in another he places both the marsupials and the
Monotremata; so that he makes man as distinct from all other mammals
as are these two latter groups conjoined. This view has not been
accepted, as far as I am aware, by any naturalist capable of forming
an independent judgment, and therefore need not here be further
considered.
We can understand why a classification founded on any single
character or organ- even an organ so wonderfully complex and important
as the brain- or on the high development of the mental faculties, is
almost sure to prove unsatisfactory. This principle has indeed been
tried with hymenopterous insects; but when thus classed by their
habits or instincts, the arrangement proved thoroughly artificial.*
Classifications may, of course, be based on any character whatever, as
on size, colour, or the element inhabited; but naturalists have long
felt a profound conviction that there is a natural system. This
system, it is now generally admitted, must be, as far as possible,
genealogical in arrangement,- that is, the co-descendants of the
same form must be kept together in one group, apart from the
co-descendants of any other form; but if the parent-forms are related,
so will be their descendants, and the two groups together will form
a larger group. The amount of difference between the several groups-
that is the amount of modification which each has undergone- is
expressed by such terms as genera, families, orders, and classes. As
we have no record of the lines of descent, the pedigree can be
discovered only by observing the degrees of resemblance between the
beings which are to be classed. For this object numerous points of
resemblance are of much more importance than the amount of
similarity or dissimilarity in a few points. If two languages were
found to resemble each other in a multitude of words and points of
construction, they would be universally recognised as having sprung
from a common source, notwithstanding that they differed greatly in
some few words or points of construction. But with organic beings
the points of resemblance must not consist of adaptations to similar
habits of life: two animals may, for instance, have had their whole
frames modified for living in the water, and yet they will not be
brought any nearer to each other in the natural system. Hence we can
see how it is that resemblances in several unimportant structures,
in useless and rudimentary organs, or not now functionally active,
or in an embryological condition, are by far the most serviceable
for classification; for they can hardly be due to adaptations within a
late period; and thus they reveal the old lines of descent or of
true affinity.
* Westwood, Modern Classification of Insects, vol. ii., 1840, p. 87.
We can further see why a great amount of modification in some one
character ought not to lead us to separate widely any two organisms. A
part which already differs much from the same part in other allied
forms has already, according to the theory of evolution, varied
much; consequently it would (as long as the organism remained
exposed to the same exciting conditions) be liable to further
variations of the same kind; and these, if beneficial, would be
preserved, and thus be continually augmented. In many cases the
continued development of a part, for instance, of the beak of a
bird, or of the teeth of a mammal, would not aid the species in
gaining its food, or for any other object; but with man we can see
no definite limit to the continued development of the brain and mental
faculties, as far as advantage is concerned. Therefore in
determining the position of man in the natural or genealogical system,
the extreme development of his brain ought not to outweigh a multitude
of resemblances in other less important or quite unimportant points.
The greater number of naturalists who have taken into
consideration the whole structure of man, including his mental
faculties, have followed Blumenbach and Cuvier, and have placed man in
a separate Order, under the title of the Bimana, and therefore on an
equality with the orders of the Quadrumana, Carnivora, &c. Recently
many of our best naturalists have recurred to the view first
propounded by Linnaeus, so remarkable for his sagacity, and have
placed man in the same Order with the Quadrumana, under the title of
the primates. The justice of this conclusion will be admitted: for
in the first place, we must bear in mind the comparative
insignificance for classification of the great development of the
brain in man, and that the strongly-marked differences between the
skulls of man and the Quadrumana (lately insisted upon by Bischoff,
Aeby, and others) apparently follow from their differently developed
brains. In the second place, we must remember that nearly all the
other and more important differences between man and the Quadrumana
are manifestly adaptive in their nature, and relate chiefly to the
erect position of man; such as the structure of his hand, foot, and
pelvis, the curvature of his spine, and the position of his head.
The family of seals offers a good illustration of the small importance
of adaptive characters for classification. These animals differ from
all other Carnivora in the form of their bodies and in the structure
of their limbs, far more than does man from the higher apes; yet in
most systems, from that of Cuvier to the most recent one by Mr.
Flower,* seals are ranked as a mere family in the Order of the
Carnivora. If man had not been his own classifier, he would never have
thought of founding a separate order for his own reception.
* Proceedings Zoological Society, 1863, p. 4.
It would be beyond my limits, and quite beyond my knowledge, even to
name the innumerable points of structure in which man agrees with
the other primates. Our great anatomist and philosopher, Prof. Huxley,
has fully discussed this subject,* and concludes that man in all parts
of his organization differs less from the higher apes, than these do
from the lower members of the same group. Consequently there "is no
justification for placing man in a distinct order."
* Evidence as to Man's Place in Nature, 1863, p. 70, et passim
In an early part of this work I brought forward various facts,
shewing how closely man agrees in constitution with the higher
mammals; and this agreement must depend on our close similarity in
minute structure and chemical composition. I gave, as instances, our
liability to the same diseases, and to the attacks of allied
parasites; our tastes in common for the same stimulants, and the
similar effects produced by them, as well as by various drugs, and
other such facts.
As small unimportant points of resemblance between man and the
Quadrumana are not commonly noticed in systematic works, and as,
when numerous, they clearly reveal our relationship, I will specify
a few such points. The relative position of our features is manifestly
the same; and the various emotions are displayed by nearly similar,
movements of the muscles and skin, chiefly above the eyebrows and
round the mouth. Some few expressions are, indeed, almost the same, as
in the weeping of certain kinds of monkeys and in the laughing noise
made by others, during which the corners of the mouth are drawn
backwards, and the lower eyelids wrinkled. The external ears are
curiously alike. In man the nose is much more prominent than in most
monkeys; but we may trace the commencement of an aquiline curvature in
the nose of the Hoolock gibbon; and this in the Semnopithecus nasica
is carried to a ridiculous extreme.
The faces of many monkeys are ornamented with beards, whiskers, or
moustaches. The hair on the head grows to a great length in some
species of Semnopithecus;* and in the bonnet monkey (Macacus radiatus)
it radiates from a point on the crown, with a parting down the middle.
It is commonly said that the forehead gives to man his noble and
intellectual appearance; but the thick hair on the head of the
bonnet monkey terminates downwards abruptly, and is succeeded by
hair so short and fine that at a little distance the forehead, with
the exception of the eyebrows, appears quite naked. It has been
erroneously asserted that eyebrows are not present in any monkey. In
the species just named the degree of nakedness of the forehead differs
in different individuals; and Eschricht states*(2) that in our
children the limit between the hairy scalp and the naked forehead is
sometimes not well defined; so that here we seem to have a trifling
case of reversion to a progenitor, in whom the forehead had not as yet
become quite naked.
* Isidore Geoffroy St-Hilaire, Hist. Nat. Gen., tom. ii., 1859, p.
217.
*(2) "Uber die Richtung der Haare, &c.," Muller's Archiv fur Anat.
und Phys., 1837, s. 51.
It is well known that the hair on our arms tends to converge from
above and below to a point at the elbow. This curious arrangement,
so unlike that in most of the lower mammals, is common to the gorilla,
chimpanzee, orang, some species of Hylobates, and even to some few
American monkeys. But in Hylobates agilis the hair on the forearm is
directed downwards or towards the wrist in the ordinary manner; and in
H. lar it is nearly erect, with only a very slight forward
inclination; so that in this latter species it is in a transitional
state. It can hardly be doubted that with most mammals the thickness
of the hair on the back and its direction, is adapted to throw off the
rain; even the transverse hairs on the fore-legs of a dog may serve
for this end when he is coiled up asleep. Mr. Wallace, who has
carefully studied the habits of the orang, remarks that the
convergence of the hair towards the elbow on the arms of the orang may
be explained as serving to throw off the rain, for this animal
during rainy weather sits with its arms bent, and with the hands
clasped round a branch or over its head. According to Livingstone, the
gorilla also "sits in pelting rain with his hands over his head."*
If the above explanation is correct, as seems probable, the
direction of the hair on our own arms offers a curious record of our
former state; for no one supposes that it is now of any use in
throwing off the rain; nor, in our present erect condition, is it
properly directed for this purpose.
* Quoted by Reade, African Sketch Book, vol i., 1873, p. 152.
It would, however, be rash to trust too much to the principle of
adaptation in regard to the direction of the hair in man or his
early progenitors; for it is impossible to study the figures given
by Eschricht of the arrangement of the hair on the human foetus
(this being the same as in the adult) and not agree with this
excellent observer that other and more complex causes have intervened.
The points of convergence seem to stand in some relation to those
points in the embryo which are last closed in during development.
There appears, also, to exist some relation between the arrangement of
the hair on the limbs, and the course of the medullary arteries.*
* On the hair in Hylobates, see Natural History of Mammals, by C. L.
Martin, 1841, p. 415. Also, Isidore Geoffroy on the American monkeys
and other kinds, Hist. Nat. Gen., vol. ii., 1859, pp. 216, 243.
Eschricht, ibid., ss. 46, 55, 61. Owen, Anatomy of Vertebrates, vol.
iii., p. 619. Wallace, Contributions to the Theory of Natural
Selection, 1870, p. 344.
It must not be supposed that the resemblances between man and
certain apes in the above and in many other points- such as in
having a naked forehead, long tresses on the head, &c.,- are all
necessarily the result of unbroken inheritance from a common
progenitor, or of subsequent reversion. Many of these resemblances are
more probably due to analogous variation, which follows, as I have
elsewhere attempted to shew,* from co-descended organisms having a
similar constitution, and having been acted on by like causes inducing
similar modifications. With respect to the similar direction of the
hair on the fore-arms of man and certain monkeys, as this character is
common to almost all the anthropomorphous apes, it may probably be
attributed to inheritance; but this is not certain, as some very
distinct American monkeys are thus characterised.
* Origin of Species. The Variation of Animals and Plants under
Domestication, vol. ii., 1868, p. 348.
Although, as we have now seen, man has no just right to form a
separate Order for his own reception, he may perhaps claim a
distinct sub-order or family. Prof. Huxley, in his last work,* divides
the primates into three suborders; namely, the Anthropidae with man
alone, the Simiadae including monkeys of all kinds, and the
Lemuridae with the diversified genera of lemurs. As far as differences
in certain important points of structure are concerned, man may no
doubt rightly claim the rank of a sub-order; and this rank is too low,
if we look chiefly to his mental faculties. Nevertheless, from a
genealogical point of view it appears that this rank is too high,
and that man ought to form merely a family, or possibly even only a
sub-family. If we imagine three lines of descent proceeding from a
common stock, it is quite conceivable that two of them might after the
lapse of ages be so slightly changed as still to remain as species
of the same genus, whilst the third line might become so greatly
modified as to deserve to rank as a distinct sub-family, or even
Order. But in this case it is almost certain that the third line would
still retain through inheritance numerous small points of
resemblance with the other two. Here, then, would occur the
difficulty, at present insoluble, how much weight we ought to assign
in our classifications to strongly-marked differences in some few
points,- that is, to the amount of modification undergone; and how
much to close resemblance in numerous unimportant points, as
indicating the lines of descent or genealogy. To attach much weight to
the few but strong differences is the most obvious and perhaps the
safest course, though it appears more correct to pay great attention
to the many small resemblances, as giving a truly natural
classification.
* An Introduction to the Classification of Animals, 1869, p. 99.
In forming a judgment on this head with reference to man, we must
glance at the classification of the Simiadae. This family is divided
by almost all naturalists into the catarhine group, or Old World
monkeys, all of which are characterised (as their name expresses) by
the peculiar structure of their nostrils, and by having four premolars
in each jaw; and into the platyrhine group or New World monkeys
(including two very distinct sub-groups), all of which are
characterised by differently constructed nostrils, and by having six
premolars in each jaw. Some other small differences might be
mentioned. Now man unquestionably belongs in his dentition, in the
structure of his nostrils, and some other respects, to the catarhine
or Old World division; nor does he resemble the platyrhines more
closely than the catarhines in any characters, excepting in a few of
not much importance and apparently of an adaptive nature. It is
therefore against all probability that some New World species should
have formerly varied and produced a man-like creature, with all the
distinctive characters proper to the Old World division; losing at the
same time all its own distinctive characters. There can, consequently,
hardly be a doubt that man is an off-shoot from the Old World simian
stem; and that under a genealogical point of view he must be classed
with the catarhine division.*
* This is nearly the same classification as that provisionally
adopted by Mr. St. G. Mivart, Transactions, Philosophical Society,
1867, p. 300, who, after separating the Lemuridae, divides the
remainder of the Primates into the Hominidae, the Simiadae which
answer to the catarhines, the Cebidae, and the Hapalidae,- these two
latter groups answering to the platyrhines. Mr. Mivart still abides by
the same view; see Nature, 1871, p. 481.
The anthropomorphous apes, namely the gorilla, chimpanzee, orang,
and Hylobates, are by most naturalists separated from the other Old
World monkeys, as a distinct sub-group. I am aware that Gratiolet,
relying on the structure of the brain, does not admit the existence of
this sub-group, and no doubt it is a broken one. Thus the orang, as
Mr. St. G. Mivart remarks, "is one of the most peculiar and aberrant
forms to be found in the Order."* The remaining non-anthropomorphous
Old World monkeys, are again divided by some naturalists into two or
three smaller subgroups; the genus Semnopithecus, with its peculiar
sacculated stomach, being the type of one sub-group. But it appears
from M. Gaudry's wonderful discoveries in Attica, that during the
Miocene period a form existed there, which connected Semnopithecus and
Macacus; and this probably illustrates the manner in which the other
and higher groups were once blended together.
* Transactions, Zoolog. Soc., vol. vi., 1867, p. 214.
If the anthropomorphous apes be admitted to form a natural
sub-group, then as man agrees with them, not only in all those
characters which he possesses in common with the whole catarhine
group, but in other peculiar characters, such as the absence of a tail
and of callosities, and in general appearance, we may infer that
some ancient member of the anthropomorphous sub-group gave birth to
man. It is not probable that, through the law of analogous
variation, a member of one of the other lower sub-groups should have
given rise to a man-like creature, resembling the higher
anthropomorphous apes in so many respects. No doubt man, in comparison
with most of his allies, has undergone an extraordinary amount of
modification, chiefly in consequence of the great development of his
brain and his erect position; nevertheless, we should bear in mind
that he "is but one of several exceptional forms of primates."*
* Mr. St. G. Mivart, Transactions of the Philosophical Society,
1867, p. 410.
Every naturalist, who believes in the principle of evolution, will
grant that the two main divisions of the Simiadae, namely the
catarhine and platyrhine monkeys, with their sub-groups, have all
proceeded from some one extremely ancient progenitor. The early
descendants of this progenitor, before they had diverged to any
considerable extent from each other, would still have formed a
single natural group; but some of the species or incipient genera
would have already begun to indicate by their diverging characters the
future distinctive marks of the catarhine and platyrhine divisions.
Hence the members of this supposed ancient group would not have been
so uniform in their dentition, or in the structure of their
nostrils, as are the existing catarhine monkeys in one way and the
platyrhines in another way, but would have resembled in this respect
the allied Lemuridae, which differ greatly from each other in the form
of their muzzles,* and to an extraordinary degree in their dentition.
* Messrs. Murie and Mivart on the Lemuroidea, Transactions,
Zoological Society, vol. vii, 1869, p. 5.
The catarhine and platyrhine monkeys agree in a multitude of
characters, as is shewn by their unquestionably belonging to one and
the same Order. The many characters which they possess in common can
hardly have been independently acquired by so many distinct species;
so that these characters must have been inherited. But a naturalist
would undoubtedly have ranked as an ape or a monkey, an ancient form
which possessed many characters common to the catarhine and platyrhine
monkeys, other characters in an intermediate condition, and some
few, perhaps, distinct from those now found in either group. And as
man from a genealogical point of view belongs to the catarhine or
Old World stock, we must conclude, however much the conclusion may
revolt our pride, that our early progenitors would have been
properly thus designated.* But we must not fall into the error of
supposing that the early progenitors of the whole simian stock,
including man, was identical with, or even closely resembled, any
existing ape or monkey.
* Haeckel has come to this same conclusion. See "Uber die Entstehung
des Menschengeschlechts," in Virchow's Sammlung. gemein. wissen.
Vortrage, 1868, s. 61. Also his Naturliche Schopfungsgeschicte,
1868, in which he gives in detail his views on the genealogy of man.
On the Birthplace and Antiquity of Man.- We are naturally led to
enquire, where was the birthplace of man at that stage of descent when
our progenitors diverged from the catarhine stock? The fact that
they belonged to the stock clearly shews that they inhabited the Old
World; but not Australia nor any oceanic island, as we may infer
from the laws of geographical distribution. In each great region of
the world the living mammals are closely related to the extinct
species of the same region. It is therefore probable that Africa was
formerly inhabited by extinct apes closely allied to the gorilla and
chimpanzee; and as these two species are now man's nearest allies,
it is somewhat more probable that our early progenitors lived on the
African continent than elsewhere. But it is useless to speculate on
this subject; for two or three anthropomorphous apes, one the
Dryopithecus* of Lartet, nearly as large as a man, and closely
allied to Hylobates, existed in Europe during the Miocene age; and
since so remote a period the earth has certainly undergone many
great revolutions, and there has been ample time for migration on
the largest scale.
* Dr. C Forsyth Major, "Sur les Singes fossiles trouves en
Italie," Soc. Ital. des Sc. Nat., tom., xv., 1872.
At the period and place, whenever and wherever it was, when man
first lost his hairy covering, he probably inhabited a hot country;
a circumstance favourable for the frugi-ferous diet on which,
judging from analogy, he subsisted. We are far from knowing how long
ago it was when man first diverged from the catarhine stock; but it
may have occurred at an epoch as remote as the Eocene period; for that
the higher apes had diverged from the lower apes as early as the Upper
Miocene period is shewn by the existence of the Dryopithecus. We are
also quite ignorant at how rapid a rate organisms, whether high or low
in the scale, may be modified under favourable circumstances; we know,
however, that some have retained the same form during an enormous
lapse of time. From what we see going on under domestication, we learn
that some of the co-descendants of the same species may be not at all,
some a little, and some greatly changed, all within the same period.
Thus it may have been with man, who has undergone a great amount of
modification in certain characters in comparison with the higher apes.
The great break in the organic chain between man and his nearest
allies, which cannot be bridged over by any extinct or living species,
has often been advanced as a grave objection to the belief that man is
descended from some lower form; but this objection will not appear
of much weight to those who, from general reasons, believe in the
general principle of evolution. Breaks often occur in all parts of the
series, some being wide, sharp and defined, others less so in
various degrees; as between the orang and its nearest allies-
between the Tarsius and the other Lemuridae- between the elephant, and
in a more striking manner between the Ornithorhynchus or Echidna,
and all other mammals. But these breaks depend merely on the number of
related forms which have become extinct. At some future period, not
very distant as measured by centuries, the civilised races of man will
almost certainly exterminate, and replace, the savage races throughout
the world. At the same time the anthropomorphous apes, as Professor
Schaaffhausen has remarked,* will no doubt be exterminated. The
break between man and his nearest allies will then be wider, for it
will intervene between man in a more civilised state, as we may
hope, even than the Caucasian, and some ape as low as a baboon,
instead of as now between the negro or Australian and the gorilla.
* Anthropological Review, April, 1867, p. 236
With respect to the absence of fossil remains, serving to connect
man with his ape-like progenitors, no one will lay much stress on this
fact who reads Sir C. Lyell's discussion,* where he shews that in
all the vertebrate classes the discovery of fossil remains has been
a very slow and fortuitous process. Nor should it be forgotten that
those regions which are the most likely to afford remains connecting
man with some extinct ape-like creature, have not as yet been searched
by geologists.
* Elements of Geology, 1865, pp. 583-585. Antiquity of Man, 1863, p.
145.
Lower Stages in the Genealogy of Man.- We have seen that man appears
to have diverged from the catarhine or Old World division of the
Simiadae, after these had diverged from the New World division. We
will now endeavour to follow the remote traces of his genealogy,
trusting principally to the mutual affinities between the various
classes and orders, with some slight reference to the periods, as
far as ascertained, of their successive appearance on the earth. The
Lemuridae stand below and near to the Simiadae, and constitute a
very distinct family of the primates, or, according to Haeckel and
others, a distinct Order. This group is diversified and broken to an
extraordinary degree, and includes many aberrant forms. It has,
therefore, probably suffered much extinction. Most of the remnants
survive on islands, such as Madagascar and the Malayan archipelago,
where they have not been exposed to so severe a competition as they
would have been on well-stocked continents. This group likewise
presents many gradations, leading, as Huxley remarks,* "insensibly
from the crown and summit of the animal creation down to creatures
from which there is but a step, as it seems, to the lowest,
smallest, and least intelligent of the placental mammalia." From these
various considerations it is probable that the Simiadae were
originally developed from the progenitors of the existing Lemuridae;
and these in their turn from forms standing very low in the
mammalian series.
* Man's Place in Nature, p. 105.
The marsupials stand in many important characters below the
placental mammals. They appeared at an earlier geological period,
and their range was formerly much more extensive than at present.
Hence the Placentata are generally supposed to have been derived
from the Implacentata or marsupials; not, however, from forms
closely resembling the existing marsupials, but from their early
progenitors. The Monotremata are plainly allied to the marsupials,
forming a third and still lower division in the great mammalian
series. They are represented at the present day solely by the
Ornithorhynchus and Echidna; and these two forms may be safely
considered as relics of a much larger group, representatives of
which have been preserved in Australia through some favourable
concurrence of circumstances. The Monotremata are eminently
interesting, as leading in several important points of structure
towards the class of reptiles.
In attempting to trace the genealogy of the Mammalia, and
therefore of man, lower down in the series, we become involved in
greater and greater obscurity; but as a most capable judge, Mr.
Parker, has remarked, we have good reason to believe, that no true
bird or reptile intervenes in the direct line of descent. He who
wishes to see what ingenuity and knowledge can effect, may consult
Prof. Haeckel's works.* I will content myself with a few general
remarks. Every evolutionist will admit that the five great
vertebrate classes, namely, mammals, birds, reptiles, amphibians,
and fishes, are descended from some one prototype; for they have
much in common, especially during their embryonic state. As the
class of fishes is the most lowly organised, and appeared before the
others, we may conclude that all the members of the vertebrate kingdom
are derived from some fishlike animal. The belief that animals so
distinct as a monkey, an elephant, a humming-bird, a snake, a frog,
and a fish, &c., could all have sprung from the same parents, will
appear monstrous to those who have not attended to the recent progress
of natural history. For this belief implies the former existence of
links binding closely together all these forms, now so utterly unlike.
* Elaborate tables are given in his Generelle Morphologie (B. ii.,
s. cliii. and s. 425); and with more especial reference to man in
his Naturliche Schopfungsgeschichte, 1868. Prof. Huxley, in
reviewing this latter work (The Academy, 1869, p. 42), says that he
considers the phylum or lines of descent of the Vertebrata to be
admirably discussed by Haeckel, although he differs on some points. He
expresses, also, his high estimate of the general tenor and spirit
of the whole work.
Nevertheless, it is certain that groups of animals have existed,
or do now exist, which serve to connect several of the great
vertebrate classes more or less closely. We have seen that the
Ornithorhynchus graduates towards reptiles; and Prof. Huxley has
discovered, and is confirmed by Mr. Cope and others, that the
dinosaurians are in many important characters intermediate between
certain reptiles and certain birds- the birds referred to being the
ostrich-tribe (itself a widely-diffused remnant of a larger group) and
the Archeopteryx, that strange secondary bird, with a long lizard-like
tail. Again, according to Prof. Owen,* the ichthyosaurians- great
sea-lizards furnished with paddles- present many affinities with
fishes, or rather, according to Huxley, with amphibians; a class
which, including in its highest division frogs and toads, is plainly
allied to the ganoid fishes. These latter fishes swarmed during the
earlier geological periods, and were constructed on what is called a
generalised type, that is, they presented diversified affinities
with other groups of organisms. The Lepidosiren is also so closely
allied to amphibians and fishes, that naturalists long disputed in
which of these two classes to rank it; it, and also some few ganoid
fishes, have been preserved from utter extinction by inhabiting
rivers, which are harbours of refuge, and are related to the great
waters of the ocean in the same way that islands are to continents.
* Palaeontology 1860, p. 199.
Lastly, one single member of the immense and diversified class of
fishes, namely, the lancelet or amphioxus, is so different from all
other fishes, that Haeckel maintains that it ought to form a
distinct class in the vertebrate kingdom. This fish is remarkable
for its negative characters; it can hardly be said to possess a brain,
vertebral column, or heart, &c.; so that it was classed by the older
naturalists amongst the worms. Many years ago Prof. Good sir perceived
that the lancelet presented some affinities with the ascidians,
which are invertebrate, hermaphrodite, marine creatures permanently
attached to a support. They hardly appear like animals, and consist of
a simple, tough, leathery sack, with two small projecting orifices.
They belong to the Mulluscoida of Huxley- a lower division of the
great kingdom of the Mollusca; but they have recently been placed by
some naturalists amongst the Vermes or worms. Their larvae somewhat
resemble tadpoles in shape,* and have the power of swimming freely
about. Mr. Kovalevsky*(2) has lately observed that the larvae of
ascidians are related to the Vertebrata, in their manner of
development, in the relative position of the nervous system, and in
possessing a structure closely like the chorda dorsalis of
vertebrate animals; and in this he has been since confirmed by Prof.
Kupffer. M. Kovalevsky writes to me from Naples, that he has now
carried these observations yet further, and should his results be well
established, the whole will form a discovery of the very greatest
value. Thus, if we may rely on embryology, ever safest guide in
classification, it seems that we have at last gained a clue to the
source whence the Vertebrata were derived.*(3) We should then be
justified in believing that at an extremely remote period a group of
animals existed, resembling in many respects the larvae of our present
ascidians, which diverged into two great branches- the one
retrograding in development and producing the present class of
ascidians, the other rising to the crown and summit of the animal
kingdom by giving birth to the Vertebrata.
* At the Falkland Islands I had the satisfaction of seeing, in
April, 1833, and therefore some years before any other naturalist, the
locomotive larvae of a compound ascidian, closely allied to
Synoicum, but apparently generically distinct from it. The tail was
about five times as long as the oblong head, and terminated in a
very fine filament. It was, as sketched by me under a simple
microscope, plainly divided by transverse opaque partitions, which I
presume represent the great cells figured by Kovalevsky. At an early
stage of development the tail was closely coiled round the head of the
larva.
*(2) Memoires de l'Acad. des Sciences de St. Petersbourg, tom. x.,
No. 15, 1866.
*(3) But I am bound to add that some competent judges dispute this
conclusion; for instance, M. Giard, in a series of papers in the
Archives de Zoologie Experimentale, for 1872. Nevertheless, this
naturalist remarks, p. 281, "L'organisation de la larve ascidienne
en dehors de toute hypothese et de toute theorie, nous montre
comment la nature peut produire la disposition fondamentale du type
vertebre (l'existence d'une corde dorsale) chez un invertebre par la
seule condition vitale de l'adaptation, et cette simple possibilite du
passage supprime l'abime entre les deux sous-regnes, encore bien qu'en
ignore par ou le passage sest fait en realite."
We have thus far endeavoured rudely to trace the genealogy of the
Vertebrata by the aid of their mutual affinities. We will now look
to man as he exists; and we shall, I think, be able partially to
restore the structure of our early progenitors, during successive
periods, but not in due order of time. This, can be effected by
means of the rudiments which man still retains, by the characters
which occasionally make their appearance in him through reversion, and
by the aid of the principles of morphology and embryology. The various
facts, to which I shall here allude, have been given in the previous
chapters.
The early progenitors of man must have been once covered with
hair, both sexes having beards; their ears were probably pointed,
and capable of movement; and their bodies were provided with a tail,
having the proper muscles. Their limbs and bodies were also acted on
by many muscles which now only occasionally reappear, but are normally
present in the Quadrumana. At this or some earlier period, the great
artery and nerve of the humerus ran through a supra-condyloid foramen.
The intestine gave forth a much larger diverticulum or caecum than
that now existing. The foot was then prehensile, judging from the
condition of the great toe in the foetus; and our progenitors, no
doubt, were arboreal in their habits, and frequented some warm,
forest-clad land. The males had great canine teeth, which served
them as formidable weapons. At a much earlier period the uterus was
double; the excreta were voided through a cloaca; and the eye was
protected by a third eyelid or nictitating membrane. At a still
earlier period the progenitors of man must have been aquatic in
their habits; for morphology plainly tells us that our lungs consist
of a modified swimbladder, which once served as a float. The clefts on
the neck in the embryo of man show where the branchiae once existed.
In the lunar or weekly recurrent periods of some of our functions we
apparently still retain traces of our primordial birthplace, a shore
washed by the tides. At about this same early period the true
kidneys were replaced by the corpora wolffiana. The heart existed as a
simple pulsating vessel; and the chorda dorsalis took the place of a
vertebral column. These early ancestors of man, thus seen in the dim
recesses of time, must have been as simply, or even still more
simply organised than the lancelet or amphioxus.
There is one other point deserving a fuller notice. It has long been
known that in the vertebrate kingdom one sex bears rudiments of
various accessory parts, appertaining to the reproductive system,
which properly belong to the opposite sex; and it has now been
ascertained that at a very early embryonic period both sexes possess
true male and female glands. Hence some remote progenitor of the whole
vertebrate kingdom appears to have been hermaphrodite or androgynous.*
But here we encounter a singular difficulty. In the mammalian class
the males possess rudiments of a uterus with the adjacent passage,
in their vesiculae prostaticae; they bear also rudiments of mammae,
and some male marsupials have traces of a marsupial sack.*(2) Other
analogous facts could be added. Are we, then, to suppose that some
extremely ancient mammal continued androgynous, after it had
acquired the chief distinctions of its class, and therefore after it
had diverged from the lower classes of the vertebrate kingdom? This
seems very improbable, for we have to look to fishes, the lowest of
all the classes, to find any still existent androgynous forms.*(3)
That various accessory parts, proper to each sex, are found in a
rudimentary condition in the opposite sex, may be explained by such
organs having been gradually acquired by the one sex, and then
transmitted in a more or less imperfect state to the other. When we
treat of sexual selection, we shall meet with innumerable instances of
this form of transmission,- as in the case of the spurs, plumes, and
brilliant colours, acquired for battle or ornament by male birds,
and inherited by the females in an imperfect or rudimentary condition.
* This is the conclusion of Prof. Gegenbaur, one of the highest
authorities in comparative anatomy: see Grundzuge der vergleich.
Anat., 1870, s. 876. The result has been arrived at chiefly from the
study of the Amphibia; but it appears from the researches of
Waldeyer (as quoted in Journal of Anat. and Phys., 1869, p. 161), that
the sexual organs of even "the higher vertebrata are, in their early
condition, hermaphrodite." Similar views have long been held by some
authors, though until recently without a firm basis.
*(2) The male Thylacinus offers the best instance. Owen, Anatomy
of Vertebrates, vol. iii., p. 771.
*(3) Hermaphroditism has been observed in several species of
Serranus, as well as in some other fishes, where it is either normal
and symmetrical, or abnormal and unilateral. Dr. Zouteveen has given
me references on this subject, more especially to a paper by Prof.
Halbertsma, in the Transact. of the Dutch Acad. of Sciences, vol. xvi.
Dr. Gunther doubts the fact, but it has now been recorded by too
many good observers to be any longer disputed. Dr. M. Lessona writes
to me, that he has verified the observations made by Cavolini on
Serranus. Prof. Ercolani has recently shewn (Acad. delle Scienze,
Bologna, Dec. 28, 1871) that eels are androgynous.
The possession by male mammals of functionally imperfect mammary
organs is, in some respects, especially curious. The Monotremata
have the proper milk-secreting glands with orifices, but no nipples;
and as these animals stand at the very base of the mammalian series,
it is probable that the progenitors of the class also had
milk-secreting glands, but no nipples. This conclusion is supported by
what is known of their manner of development; for Professor Turner
informs me, on the authority of Kolliker and Langer, that in the
embryo the mammary glands can be distinctly traced before the
nipples are in the least visible; and the development of successive
parts in the individual generally represents and accords with the
development of successive beings in the same line of descent. The
marsupials differ from the Monotremata by possessing nipples; so
that probably these organs were first acquired by the marsupials,
after they had diverged from, and risen above, the Monotremata, and
were then transmitted to the placental mammals.* No one will suppose
that the marsupials still remained androgynous, after they had
approximately acquired their present structure. How then are we to
account for male mammals possessing mammae? It is possible that they
were first developed in the females and then transferred to the males,
but from what follows this is hardly probable.
* Prof. Gegenbaur has shewn (Jenaische Zeitschrift, Bd. vii., p.
212) that two distinct types of nipples prevail throughout the several
mammalian orders, but that it is quite intelligible how both could
have been derived from the nipples of the marsupials, and the latter
from those of the Monotremata. See, also, a memoir by Dr. Max Huss, on
the mammary glands, ibid., B. viii., p. 176.
It may be suggested, as another view, that long after the
progenitors of the whole mammalian class had ceased to be androgynous,
both sexes yielded milk, and thus nourished their young; and in the
case of the marsupials, that both sexes carried their young in
marsupial sacks. This will not appear altogether improbable, if we
reflect that the males of existing syngnathous fishes receive the eggs
of the females in their abdominal pouches, hatch them, and afterwards,
as some believe, nourish the young;* - that certain other male
fishes hatch the eggs within their mouths or branchial cavities;- that
certain male toads take the chaplets of eggs from the females, and
wind them round their own thighs, keeping them there until the
tadpoles are born;- that certain male birds undertake the whole duty
of incubation, and that male pigeons, as well as the females, feed
their nestlings with a secretion from their crops. But the above
suggestion first occurred to me from mammary glands of male mammals
being so much more perfectly developed than the rudiments of the other
accessory reproductive parts, which are found in the one sex though
proper to the other. The mammary glands and nipples, as they exist
in male mammals, can indeed hardly be called rudimentary; they are
merely not fully developed, and not functionally active. They are
sympathetically affected under the influence of certain diseases, like
the same organs in the female. They often secrete a few drops of
milk at birth and at puberty: this latter fact occurred in the curious
case before referred to, where a young man possessed two pairs of
mammee. In man and some other male mammals these organs have been
known occasionally to become so well developed during maturity as to
yield a fair supply of milk. Now if we suppose that during a former
prolonged period male mammals aided the females in nursing their
offspring,*(2) and that afterwards from some cause (as from the
production of a smaller number of young) the males ceased to give this
aid, disuse of the organs during maturity would lead to their becoming
inactive; and from two well-known principles of inheritance, this
state of inactivity would probably be transmitted to the males at
the corresponding age of maturity. But at an earlier age these
organs would be left unaffected, so that they would be almost
equally well developed in the young of both sexes.
* Mr. Lockwood believes (as quoted in Quart. Journal of Science,
April, 1868, p. 269), from what he has observed of the development
of Hippocampus, that the walls of the abdominal pouch of the male in
some way afford nourishment. On male fishes hatching the ova in
their mouths, see a very interesting paper by Prof. Wyman, in Proc.
Boston Soc. of Nat. Hist., Sept. 15, 1857; also Prof. Turner, in
Journal of Anatomy and Physiology, Nov. 1, 1866, p. 78. Dr. Gunther
has likewise described similar cases.
*(2) Mlle. C. Royer has suggested a similar view in her Origine de
l'homme, &c., 1870.
Conclusion.- Von Baer has defined advancement or progress in the
organic scale better than any one else, as resting on the amount of
differentiation and specialisation of the several parts of a being,-
when arrived at maturity, as I should be inclined to add. Now as
organisms have become slowly adapted to diversified lines of life by
means of natural selection, their parts will have become more and more
differentiated and specialised for various functions from the
advantage gained by the division of physiological labour. The same
part appears often to have been modified first for one purpose, and
then long afterwards for some other and quite distinct purpose; and
thus all the parts are rendered more and more complex. But each
organism still retains the general type of structure of the progenitor
from which it was aboriginally derived. In accordance with this view
it seems, if we turn to geological evidence, that organisation on
the whole has advanced throughout the world by slow and interrupted
steps. In the great kingdom of the Vertebrata it has culminated in
man. It must not, however, be supposed that groups of organic beings
are always supplanted, and disappear as soon as they have given
birth to other and more perfect groups. The latter, though
victorious over their predecessors, may not have become better adapted
for all places in the economy of nature. Some old forms appear to have
survived from inhabiting protected sites, where they have not been
exposed to very severe competition; and these often aid us in
constructing our genealogies, by giving us a fair idea of former and
lost populations. But we must not fall into the error of looking at
the existing members of any lowly-organised group as perfect
representatives of their ancient predecessors.
The most ancient progenitors in the kingdom of the Vertebrata, at
which we are able to obtain an obscure glance, apparently consisted of
a group of marine animals,* resembling the larvae of existing
ascidians. These animals probably gave rise to a group of fishes, as
lowly organised as the lancelet; and from these the ganoids, and other
fishes like the Lepidosiren, must have been developed. From such
fish a very small advance would carry us on to the amphibians. We have
seen that birds and reptiles were once intimately connected
together; and the Monotremata now connect mammals with reptiles in a
slight degree. But no one can at present say by what line of descent
the three higher and related classes, namely, mammals, birds, and
reptiles, were derived from the two lower vertebrate classes,
namely, amphibians and fishes. In the class of mammals the steps are
not difficult to conceive which led from the ancient Monotremata to
the ancient marsupials; and from these to the early progenitors of the
placental mammals. We may thus ascend to the Lemuridae; and the
interval is not very wide from these to the Simiadae. The Simiadae
then branched off into two great stems, the New World and Old World
monkeys; and from the latter, at a remote period, Man, the wonder
and glory of the Universe, proceeded.
* The inhabitants of the seashore must be greatly affected by the
tides; animals living either about the mean high-water mark, or
about the mean low-water mark, pass through a complete cycle of
tidal changes in a fortnight. Consequently, their food supply will
undergo marked changes week by week. The vital functions of such
animals, living under these conditions for many generations, can
hardly fail to run their course in regular weekly periods. Now it is a
mysterious fact that in the higher and now terrestrial Vertebrata,
as well as in other classes, many normal and abnormal processes one or
more whole weeks as their periods; this would be rendered intelligible
if the Vertebrata are descended from an animal allied to the
existing tidal ascidians. Many instances of such periodic processes
might be given, as the gestation of mammals, the duration of fevers,
&c. The hatching of eggs affords also a good example, for, according
to Mr. Bartlett (Land and Water, Jan. 7, 1871), the eggs of the pigeon
are hatched in two weeks; those of the fowl in three; those of the
duck in four; those of the goose in five; and those of the ostrich
in seven weeks. As far as we can judge, a recurrent period, if
approximately of the right duration for any process or function, would
not, when once gained, be liable to change; consequently it might be
thus transmitted through almost any number of generations. But if
the function changed, the period would have to change, and would be
apt to change almost abruptly by a whole week. This conclusion, if
sound, is highly remarkable; for the period of gestation in each
mammal, and the hatching of each bird's eggs, and many other vital
processes, thus betray to us the primordial birthplace of these
animals.
Thus we have given to man a pedigree of prodigious length, but
not, it may be said, of noble quality. The world, it has often been
remarked, appears as if it had long been preparing for the advent of
man: and this, in one sense is strictly true, for he owes his birth to
a long line of progenitors. If any single link in this chain had never
existed, man would not have been exactly what he now is. Unless we
wilfully close our eyes, we may, with our present knowledge,
approximately recognise our parentage; nor need we feel ashamed of it.
The most humble organism is something much higher than the inorganic
dust under our feet; and no one with an unbiased mind can study any
living creature, however humble, without being struck with
enthusiasm at its marvellous structure and properties.
CHAPTER VII.
ON THE RACES OF MAN.
IT is not my intention here to describe the several so-called
races of men; but I am about to enquire what is the value of the
differences between them under a classificatory point of view, and how
they have originated. In determining whether two or more allied
forms ought to be ranked as species or varieties, naturalists are
practically guided by the following considerations; namely, the amount
of difference between them, and whether such differences relate to few
or many points of structure, and whether they are of physiological
importance; but more especially whether they are constant. Constancy
of character is what is chiefly valued and sought for by
naturalists. Whenever it can be shewn, or rendered probable, that
the forms in question have remained distinct for a long period, this
becomes an argument of much weight in favour of treating them as
species. Even a slight degree of sterility between any two forms
when first crossed, or in their offspring, is generally considered
as a decisive test of their specific distinctness; and their continued
persistence without blending within the same area, is usually accepted
as sufficient evidence, either of some degree of mutual sterility,
or in the case of animals of some mutual repugnance to pairing.
Independently of fusion from intercrossing, the complete absence, in
a well-investigated region, of varieties linking together any two
closely-allied forms, is probably the most important of all the
criterions of their specific distinctness; and this is a somewhat
different consideration from mere constancy of character, for two
forms may be highly variable and yet not yield intermediate varieties.
Geographical distribution is often brought into play unconsciously and
sometimes consciously; so that forms living in two widely separated
areas, in which most of the other inhabitants are specifically
distinct, are themselves usually looked at as distinct; but in truth
this affords no aid in distinguishing geographical races from
so-called good or true species.
Now let us apply these generally-admitted principles to the
races of man, viewing him in the same spirit as a naturalist would any
other animal. In regard to the amount of difference between the races,
we must make some allowance for our nice powers of discrimination
gained by the long habit of observing ourselves. In India, as
Elphinstone remarks, although a newly-arrived European cannot at first
distinguish the various native races, yet they soon appear to him
extremely dissimilar;* and the Hindoo cannot at first perceive any
difference between the several European nations. Even the most
distinct races of man are much more like each other in form than would
at first be supposed; certain negro tribes must be excepted, whilst
others, as Dr. Rohlfs writes to me, and as I have myself seen, have
Caucasian features. This general similarity is well shewn by the
French photographs in the Collection Anthropologique du Museum de
Paris of the men belonging to various races, the greater number of
which might pass for Europeans, as many persons to whom I have shewn
them have remarked. Nevertheless, these men, if seen alive, would
undoubtedly appear very distinct, so that we are clearly much
influenced in our judgment by the mere colour of the skin and hair, by
slight differences in the features, and by expression.
* History of India, 1841, vol. i., p. 323. Father Ripa makes exactly
the same remark with respect to the Chinese.
There is, however, no doubt that the various races, when
carefully compared and measured, differ much from each other,- as in
the texture of the hair, the relative proportions of all parts of
the body,* the capacity of the lungs, the form and capacity of the
skull, and even in the convolutions of the brain.*(2) But it would
be an endless task to specify the numerous points of difference. The
races differ also in constitution, in acclimatisation and in liability
to certain diseases. Their mental characteristies are likewise very
distinct; chiefly as it would appear in their emotional, but partly in
their intellectual faculties. Every one who has had the opportunity of
comparison, must have been struck with the contrast between the
taciturn, even morose, aborigines of S. America and the
lighthearted, talkative negroes. There is a nearly similar contrast
between the Malays and the Papuans,*(3) who live under the same
physical conditions, and are separated from each other only by a
narrow space of sea.
* A vast number of measurements of whites, blacks, and Indians,
are given in the Investigations in the Military and Anthropolog.
Statistics of American Soldiers by B. A. Gould, 1869, pp. 298-358; "On
the capacity of the lungs," p. 471. See also the numerous and valuable
tables, by Dr. Weisbach, from the observations of Dr. Scherzer and Dr.
Schwarz, in the Reise der Novara: Anthropolog. Theil, 1867.
*(2) See, for instance, Mr. Marshall's account of the brain of a
bushwoman, in Philosophical Transactions, 1864, p. 519.
*(3) Wallace The Malay Archipelago, vol. ii., 1869, p. 178.
We will first consider the arguments which may be advanced in favour
of classing the races of man as distinct species, and then the
arguments on the other side. If a naturalist, who had never before
seen a Negro, Hottentot, Australian, or Mongolian, were to compare
them, he would at once perceive that they differed in a multitude of
characters, some of slight and some of considerable importance. On
enquiry he would find that they were adapted to live under widely
different climates, and that they differed somewhat in bodily
constitution and mental disposition. If he were then told that
hundreds of similar specimens could be brought from the same
countries, he would assuredly declare that they were as good species
as many to which he had been in the habit of affixing specific
names. This conclusion would be greatly strengthened as soon as he had
ascertained that these forms had all retained the same character for
many centuries; and that negroes, apparently identical with existing
negroes, had lived at least 4000 years ago.* He would also hear, on
the authority of an excellent observer, Dr. Lund,*(2) that the human
skulls found in the caves of Brazil entombed with many extinct
mammals, belonged to the same type as that now prevailing throughout
the American continent.
* With respect to the figures in the famous Egyptian caves of
Abou-Simbel, M. Pouchet says (The Plurality of the Human Races, Eng.
translat., 1864, p. 50), that he was far from finding recognisable
representations of the dozen or more nations which some authors
believe that they can recognise. Even some of the most strongly-marked
races cannot be identified with that degree of unanimity which might
have been expected from what has been written on the subject. Thus
Messrs. Nott and Gliddon (Types of Mankind, p. 148), state that
Rameses II, or the Great, has features superbly European; whereas
Knox, another firm believer in the specific distinctness of the
races of man (Races of Man, 1850, p. 201), speaking of young Memnon
(the same as Rameses II, as I am informed by Mr. Birch), insists in
the strongest manner that he is identical in character with the Jews
of Antwerp. Again, when I looked at the statue of Amunoph III, I
agreed with two officers of the establishment, both competent
judges, that he had a strongly-marked negro type of features; but
Messrs. Nott and Gliddon (ibid., p. 146, fig. 53), describe him as a
hybrid, but not of "negro intermixture."
*(2) As quoted by Nott and Gliddon, Types of Mankind, 1854, p.
439. They give also corroborative evidence; but C. Vogt thinks that
the subject requires further investigation.
Our naturalist would then perhaps turn to geographical distribution,
and he would probably declare that those forms must be distinct
species, which differ not only in appearance, but are fitted for
hot, as well as damp or dry countries, and for the arctic regions.
He might appeal to the fact that no species in the group next to
man- namely, the Quadrumana, can resist a low temperature, or any
considerable change of climate; and that the species which come
nearest to man have never been reared to maturity, even under the
temperate climate of Europe. He would be deeply impressed with the
fact, first noticed by Agassiz,* that the different races of man are
distributed over the world in the same zoological provinces, as
those inhabited by undoubtedly distinct species and genera of mammals.
This is manifestly the case with the Australian, Mongolian, and
Negro races of man; in a less well-marked manner with the
Hottentots; but plainly with the Papuans and Malays, who are
separated, as Mr. Wallace has shewn, by nearly the same line which
divides the great Malayan and Australian zoological provinces. The
aborigines of America range throughout the continent; and this at
first appears opposed to the above rule, for most of the productions
of the Southern and Northern halves differ widely: yet some few living
forms, as the opossum, range from the one into the other, as did
formerly some of the gigantic Edentata. The Esquimaux, like other
arctic animals, extend round the whole polar regions. It should be
observed that the amount of difference between the mammals of the
several zoological provinces does not correspond with the degree of
separation between the latter; so that it can hardly be considered
as an anomaly that the Negro differs more, and the American much
less from the other races of man, than do the mammals of the African
and American continents from the mammals of the other provinces.
Man, it may be added, does not appear to have aboriginally inhabited
any oceanic island; and in this respect, he resembles the other
members of his class.
* "Diversity of Origin of the Human Races," in the Christian
Examiner, July, 1850.
In determining whether the supposed varieties of the same kind of
domestic animal should be ranked as such, or as specifically distinct,
that is, whether any of them are descended from distinct wild species,
every naturalist would lay much stress on the fact of their external
parasites being specifically distinct. All the more stress would be
laid on this fact, as it would be an exceptional one; for I am
informed by Mr. Denny that the most different kinds of dogs, fowls,
and pigeons, in England, are infested by the same species of
Pediculi or lice. Now Mr. A. Murray has carefully examined the
Pediculi. collected in different countries from the different races of
man;* and he finds that they differ, not only in colour, but in the
structure of their claws and limbs. In every case in which many
specimens were obtained the differences were constant. The surgeon
of a whaling ship in the Pacific assured me that when the Pediculi,
with which some Sandwich Islanders on board swarmed, strayed on to the
bodies of the English sailors, they died in the course of three or
four days. These Pediculi were darker coloured, and appeared different
from those proper to the natives of Chiloe in South America, of
which he gave me specimens. These, again, appeared larger and much
softer than European lice. Mr. Murray procured four kinds from Africa,
namely, from the Negroes of the Eastern and Western coasts, from the
Hottentots and Kaffirs; two kinds from the natives of Australia; two
from North and two from South America. In these latter cases it may be
presumed that the Pediculi came from natives inhabiting different
districts. With insects slight structural differences, if constant,
are generally esteemed of specific value: and the fact of the races of
man being infested by parasites, which appear to be specifically
distinct, might fairly be urged as an argument that the races
themselves ought to be classed as distinct species.
* Transactions of the Royal Society of Edinburgh, vol. xxii, 1861,
p. 567.
Our supposed naturalist having proceeded thus far in his
investigation, would next enquire whether the races of men, when
crossed, were in any degree sterile. He might consult the work* of
Professor Broca, a cautious and philosophical observer, and in this he
would find good evidence that some races were quite fertile
together, but evidence of an opposite nature in regard to other races.
Thus it has been asserted that the native women of Australia and
Tasmania rarely produce children to European men; the evidence,
however, on this head has now been shewn to be almost valueless. The
half-castes are killed by the pure blacks: and an account has lately
been published of eleven half-caste youths murdered and burnt at the
same time, whose remains were found by the police.*(2) Again, it has
often been said that when mulattoes intermarry, they produce few
children; on the other hand, Dr. Bachman, of Charleston,*(3)
positively asserts that he has known mulatto families which have
intermarried for several generations, and have continued on an average
as fertile as either pure whites or pure blacks. Enquiries formerly
made by Sir C. Lyell on this subject led him, as he informs me, to the
same conclusion.*(4) In the United States the census for the year 1854
included, according to Dr. Bachman, 405,751 mulattoes; and this
number, considering all the circumstances of the case, seems small;
but it may partly be accounted for by the degraded and anomalous
position of the class, and by the profligacy of the women. A certain
amount of absorption of mulattoes into negroes must always be in
progress; and this would lead to an apparent diminution of the former.
The inferior vitality of mulattoes is spoken of in a trustworthy
work*(5) as a well-known phenomenon; and this, although a different
consideration from their lessened fertility, may perhaps be advanced
as a proof of the specific distinctness of the parent races. No
doubt both animal and vegetable hybrids, when produced from
extremely distinct species, are liable to premature death; but the
parents of mulattoes cannot be put under the category of extremely
distinct species. The common mule, so notorious for long life and
vigour, and yet so sterile, shews how little necessary connection
there is in hybrids between lessened fertility and vitality; other
analogous cases could be cited.
* On the Phenomena of Hybridity in the Genus Homo, Eng. translat.,
1864.
*(2) See the interesting letter by Mr. T. A. Murray, in the
Anthropological Review, April, 1868, p. liii. In this letter Count
Strzelecki's statement that Australian women who have borne children
to a white man, are afterwards sterile with their own race, is
disproved. M. A. de Quatrefages has also collected (Revue des Cours
Scientifiques, March, 1869, p. 239), much evidence that Australians
and Europeans are not sterile when crossed.
*(3) An Examination of Prof. Agassiz's Sketch of the Nat.
Provinces of the Animal World, Charleston, 1855, p. 44.
*(4) Dr. Rohlfs writes to me that he found the mixed races in the
Great Sahara, derived from Arabs, Berbers, and Negroes of three
tribes, extraordinarily fertile. On the other hand, Mr. Winwood
Reade informs me that the Negroes on the Gold Coast, though admiring
white men and mulattoes, have a maxim that mulattoes should not
intermarry, as the children are few and sickly. This belief, as Mr.
Reade remarks, deserves attention, as white men have visited and
resided on the Gold Coast for four hundred years, so that the
natives have had ample time to gain knowledge through experience.
*(5) Military and Anthropological Statistics of American Soldiers,
by B. A. Gould, 1869, p. 319.
Even if it should hereafter be proved that all the races of men were
perfectly fertile together, he who was inclined from other reasons
to rank them as distinct species, might with justice argue that
fertility and sterility are not safe criterions of specific
distinctness. We know that these qualities are easily affected by
changed conditions of life, or by close interbreeding, and that they
are governed by highly complex laws, for instance, that of the unequal
fertility of converse crosses between the same two species. With forms
which must be ranked as undoubted species, a perfect series exists
from those which are absolutely sterile when crossed, to those which
are almost or completely fertile. The degrees of sterility do not
coincide strictly with the degrees of difference between the parents
in external structures or habits of life. Man in many respects may
be compared with those animals which have long been domesticated,
and a large body of evidence can be advanced in favour of the
Pallasian doctrine,* that domestication tends to eliminate the
sterility which is so general a result of the crossing of species in a
state of nature. From these several considerations, it may be justly
urged that the perfect fertility of the intercrossed races of man,
if established, would not absolutely preclude us from ranking them
as distinct species.
* The Variation of Animals and Plants under Domestication, vol. ii
p. 109. I may here remind the reader that the sterility of species
when crossed is not a specially acquired quality, but, like the
incapacity of certain trees to be grafted together, is incidental on
other acquired differences. The nature these differences is unknown,
but they relate more especially to the reproductive system, and much
less so to external structure or to ordinary differences in
constitution. One important element in the sterility of crossed
species apparently lies in one or both having been long habituated
to fixed conditions; for we know that changed conditions have a
special influence on the reproductive system, and we have good
reason to believe (as before remarked) that the fluctuating conditions
of domestication tend to eliminate that sterility which is so
general with species, in a natural state, when crossed. It has
elsewhere been shewn by me (ibid., vol. ii., p. 185, and Origin of
Species, (OOS), that the sterility of crossed species has not been
acquired through natural selection: we can see that when two forms
have already been rendered very sterile, it is scarcely possible
that their sterility should be augmented by the preservation or
survival of the more and more sterile individuals; for, as the
sterility increases. fewer and fewer offspring will be produced from
which to breed, and at last only single individuals will be produced
at the rarest intervals. But there is even a higher grade of sterility
than this. Both Gartner and Kolreuter have proved that in genera of
plants, including many species, a series can be formed from species
which, when crossed, yield fewer and fewer seeds, to species which
never produce a single seed, but yet are affected by the pollen of the
other species, as shewn by the swelling of the germen. It is here
manifestly impossible to select the more sterile individuals, which
have already ceased to yield seeds; so that the acme of sterility,
when the germen alone is affected, cannot have been gained through
selection. This acme, and no doubt the other grades of sterility,
are the incidental results of certain unknown differences in the
constitution of the reproductive system of the species which are
crossed.
Independently of fertility, the characters presented by the
offspring from a cross have been thought to indicate whether or not
the parent-forms ought to be ranked as species or varieties; but after
carefully studying the evidence, I have come to the conclusion that no
general rules of this kind can be trusted. The ordinary result of a
cross is the production of a blended or intermediate form; but in
certain cases some of the offspring take closely after one
parent-form, and some after the other. This is especially apt to occur
when the parents differ in characters which first appeared as sudden
variations or monstrosities.* I refer to this point, because Dr.
Rohlfs informs me that he has frequently seen in Africa the
offspring of negroes crossed with members of other races, either
completely black or completely white, or rarely piebald. On the
other hand, it is notorious that in America mulattoes commonly present
an intermediate appearance.
* The Variation of Animals, &c., vol. ii., p. 92.
We have now seen that a naturalist might feel himself fully
justified in ranking the races of man as distinct species; for he
has found that they are distinguished by many differences in structure
and constitution, some being of importance. These differences have,
also, remained nearly constant for very long periods of time. Our
naturalist will have been in some degree influenced by the enormous
range of man, which is a great anomaly in the class of mammals, if
mankind be viewed as a single species. He will have been struck with
the distribution of the several so-called races, which accords with
that of other undoubtedly distinct species of mammals. Finally, he
might urge that the mutual fertility of all the races has not as yet
been fully proved, and even if proved would not be an absolute proof
of their specific identity.
On the other side of the question, if our supposed naturalist were
to enquire whether the forms of man keep distinct like ordinary
species, when mingled together in large numbers in the same country,
he would immediately discover that this was by no means the case. In
Brazil he would behold an immense mongrel population of Negroes and
Portuguese; in Chiloe, and other parts of South America, he would
behold the whole population consisting of Indians and Spaniards
blended in various degrees.* In many parts of the same continent he
would meet with the most complex crosses between Negroes, Indians, and
Europeans; and judging from the vegetable kingdom, such triple crosses
afford the severest test of the mutual fertility of the parent
forms. In one island of the Pacific he would find a small population
of mingled Polynesian and English blood; and in the Fiji Archipelago a
population of Polynesians and Negritos crossed in all degrees. Many
analogous cases could be added; for instance, in Africa. Hence the
races of man are not sufficiently distinct to inhabit the same country
without fusion; and the absence of fusion affords the usual and best
test of specific distinctness.
* M. de Quatrefages has given (Anthropological Review, Jan., 1869,
p. 22), an interesting account of the success and energy of the
Paulistas in Brazil, who are a much crossed race of Portuguese and
Indians, with a mixture of the blood of other races.
Our naturalist would likewise be much disturbed as soon as he
perceived that the distinctive characters of all the races were highly
variable. This fact strikes every one on first beholding the negro
slaves in Brazil, who have been imported from all parts of Africa. The
same remark holds good with the Polynesians, and with many other
races. It may be doubted whether any character can be named which is
distinctive of a race and is constant. Savages, even within the limits
of the same tribe, are not nearly so uniform in character, as has been
often asserted. Hottentot women offer certain peculiarities, more
strongly marked than those occurring in any other race, but these
are known not to be of constant occurrence. In the several American
tribes, colour and hairiness differ considerably; as does colour to
a certain degree, and the shape of the features greatly, in the
negroes of Africa. The shape of the skull varies much in some
races;* and so it is with every other character. Now all naturalists
have learnt by dearly bought experience, how rash it is to attempt
to define species by the aid of inconstant characters.
* For instance, with the aborigines of America and Australia,
Prof. Huxley says (Transact. Internat. Congress of Prehist. Arch.,
1868, p. 105), that the skulls of many South Germans and Swiss are "as
short and as broad as those of the Tartars," &c.
But the most weighty of all the arguments against treating the races
of man as distinct species, is that they graduate into each other,
independently in many cases, as far as we can judge, of their having
intercrossed. Man has been studied more carefully than any other
animal, and yet there is the greatest possible diversity amongst
capable judges whether he should be classed as a single species or
race, or as two (Virey), as three (Jacquinot), as four (Kant), five
(Blumenbach), six (Buffon), seven (Hunter), eight (Agassiz), eleven
(Pickering), fifteen (Bory de St-Vincent), sixteen (Desmoulins),
twenty-two (Morton), sixty (Crawfurd), or as sixty-three, according to
Burke.* This diversity of judgment does not prove that the races ought
not to be ranked as species, but it shews that they graduate into each
other, and that it is hardly possible to discover clear distinctive
characters between them.
* See a good discussion on this subject in Waitz, Introduction to
Anthropology, Eng. translat., 1863, pp. 198-208, 227. I have taken
some of the above statements from H. Tuttle's Origin and Antiquity
of Physical Man, Boston, 1866, p. 35.
Every naturalist who has had the misfortune to undertake the
description of a group of highly varying organisms, has encountered
cases (I speak after experience) precisely like that of man; and if of
a cautious disposition, he will end by uniting all the forms which
graduate into each other, under a single species; for he will say to
himself that he has no right to give names to objects which he
cannot define. Cases of this kind occur in the Order which include
man, namely in certain genera of monkeys; whilst in other genera, as
in Cercopithecus, most of the species can be determined with
certainty. In the American genus Cebus, the various forms are ranked
by some naturalists as species, by others as mere geographical
races. Now if numerous specimens of Cebus were collected from all
parts of South America, and those forms which at present appear to
be specifically distinct, were found to graduate into each other by
close steps, they would usually be ranked as mere varieties or
races; and this course has been followed by most naturalists with
respect to the races of man. Nevertheless, it must be confessed that
there are forms, at least in the vegetable kingdom,* which we cannot
avoid naming as species, but which are connected together by
numberless gradations, independently of intercrossing.
* Prof. Nageli has carefully described several striking cases in his
Botanische Mittheilungen, B. ii., 1866, ss. 294-369. Prof. Asa Gray
has made analogous remarks on some intermediate forms in the
Compositae of N. America.
Some naturalists have lately employed the term "sub-species" to
designate forms which possess many of the characteristics of true
species, but which hardly deserve so high a rank. Now if we reflect on
the weighty arguments above given, for raising the races of man to the
dignity of species, and the insuperable difficulties on the other side
in defining them, it seems that the term "sub-species" might here be
used with propriety. But from long habit the term "race" will
perhaps always be employed. The choice of terms is only so far
important in that it is desirable to use, as far as possible, the same
terms for the same degrees of difference. Unfortunately this can
rarely be done: for the larger genera generally include closely-allied
forms, which can be distinguished only with much difficulty, whilst
the smaller genera within the same family include forms that are
perfectly distinct; yet all must be ranked equally as species. So
again, species within the same large genus by no means resemble each
other to the same degree: on the contrary, some of them can
generally be arranged in little groups round other species, like
satellites round planets.*
* Origin of Species. (OOS)
The question whether mankind consists of one or several species
has of late years been much discussed by anthropologists, who are
divided into the two schools of monogenists and polygenists. Those who
do not admit the principle of evolution, must look at species as
separate creations, or in some manner as distinct entities; and they
must decide what forms of man they will consider as species by the
analogy of the method commonly pursued in ranking other organic beings
as species. But it is a hopeless endeavour to decide this point, until
some definition of the term "species" is generally accepted; and the
definition must not include an indeterminate element such as an act of
creation. We might as well attempt without any definition to decide
whether a certain number of houses should be called a village, town,
or city. We have a practical illustration of the difficulty in the
never-ending doubts whether many closely-allied mammals, birds,
insects, and plants, which represent each other respectively in
North America and Europe, should be ranked as species or
geographical races; and the like holds true of the productions of many
islands situated at some little distance from the nearest continent.
Those naturalists, on the other hand, who admit the principle of
evolution, and this is now admitted by the majority of rising men,
will feel no doubt that all the races of man are descended from a
single primitive stock; whether or not they may think fit to designate
the races as distinct species, for the sake of expressing their amount
of difference.* With our domestic animals the question whether the
various races have arisen from one or more species is somewhat
different. Although it may be admitted that all the races, as well
as all the natural species within the same genus, have sprung from the
same primitive stock, yet it is a fit subject for discussion,
whether all the domestic races of the dog, for instance, have acquired
their present amount of difference since some one species was first
domesticated by man; or whether they owe some of their characters to
inheritance from distinct species, which had already been
differentiated in a state of nature. With man no such question can
arise, for he cannot be said to have been domesticated at any
particular period.
* See Prof. Huxley to this effect in the Fortnightly Review, 1865,
p. 275.
During an early stage in the divergence of the races of man from a
common stock, the differences between the races and their number
must have been small; consequently as far as their distinguishing
characters are concerned, they then had less claim to rank as distinct
species than the existing so-called races. Nevertheless, so
arbitrary is the term of species, that such early races would
perhaps have been ranked by some naturalists as distinct species, if
their differences, although extremely slight, had been more constant
than they are at present, and had not graduated into each other.
It is however possible, though far from probable, that the early
progenitors of man might formerly have diverged much in character,
until they became more unlike each other than any now existing
races; but that subsequently, as suggested by Vogt,* they converged in
character. When man selects the offspring of two distinct species
for the same object, he sometimes induces a considerable amount of
convergence, as far as general appearance is concerned. This is the
case, as shown by von Nathusius,*(2) with the improved breeds of the
pig, which are descended from two distinct species; and in a less
marked manner with the improved breeds of cattle. A great anatomist,
Gratiolet, maintains that the anthropomorphous apes do not form a
natural sub-group; but that the orang is a highly developed gibbon
or Semnopithecus, the chimpanzee a highly developed Macacus, and the
gorilla a highly developed mandrill. If this conclusion, which rests
almost exclusively on brain-characters, be admitted, we should have
a case of convergence at least in external characters, for the
anthropomorphous apes are certainly more like each other in many
points, than they are to other apes. All analogical resemblances, as
of a whale to a fish, may indeed be said to be cases of convergence;
but this term has never been applied to superficial and adaptive
resemblances. It would, however be extremely rash to attribute to
convergence close similarity of character in many points of
structure amongst the modified descendants of widely distinct
beings. The form of a crystal is determined solely by the molecular
forces, and it is not surprising that dissimilar substances should
sometimes assume the same form; but with organic beings we should bear
in mind that the form of each depends on an infinity of complex
relations, namely on variations, due to causes far too intricate to be
followed,- on the nature of the variations preserved, these
depending on the physical conditions, and still more on the
surrounding organisms which compete with each,- and lastly, on
inheritance (in itself a fluctuating element) from innumerable
progenitors, all of which have had their forms determined through
equally complex relations. It appears incredible that the modified
descendants of two organisms, if these differed from each other in a
marked manner, should ever afterwards converge so closely as to lead
to a near approach to identity throughout their whole organisation. In
the case of the convergent races of pigs above referred to, evidence
of their descent from two primitive stock is, according to von
Nathusius, still plainly retained, in certain bones of their skulls.
If the races of man had descended, as is supposed by some naturalists,
from two or more species, which differed from each other as much, or
nearly as much, as does the orang from the gorilla, it can hardly be
doubted that marked differences in the structure of certain bones
would still be discoverable in man as he now exists.
* Lectures on Man, Eng. translat., 1864, p. 468.
*(2) Die Rassen des Schweines, 1860, s. 46. Vorstudien fur
Geschichte, &c., "Schweinesschadel," 1864, s. 104. With respect to
cattle, see M. de Quatrefages, Unite de l'Espece Humaine, 1861, p.
119.
Although the existing races of man differ in many respects, as in
colour, hair, shape of skull, proportions of the body, &c., yet if
their whole structure be taken into consideration they are found to
resemble each other closely in a multitude of points. Many of these
are of so unimportant or of so singular a nature, that it is extremely
improbable that they should have been independently acquired by
aboriginally distinct species or races. The same remark holds good
with equal or greater force with respect to the numerous points of
mental similarity between the most distinct races of man. The American
aborigines, Negroes and Europeans are as different from each other
in mind as any three races that can be named; yet I was incessantly
struck, whilst living with the Feugians on board the Beagle, with
the many little traits of character, shewing how similar their minds
were to ours; and so it was with a full-blooded negro with whom I
happened once to be intimate.
He who will read Mr. Tylor's and Sir J. Lubbock's interesting works*
can hardly fail to be deeply impressed with the close similarity
between the men of all races in tastes, dispositions and habits.
This is shown by the pleasure which they all take in dancing, rude
music, acting, painting, tattooing, and otherwise decorating
themselves; in their mutual comprehension of gesture-language, by
the same expression in their features, and by the same inarticulate
cries, when excited by the same emotions. This similarity, or rather
identity, is striking, when contrasted with the different
expressions and cries made by distinct species of monkeys. There is
good evidence that the art of shooting with bows and arrows has not
been handed down from any common progenitor of mankind, yet as
Westropp and Nilsson have remarked,*(2) the stone arrow-heads, brought
from the most distant parts of the world, and manufactured at the most
remote periods, are almost identical; and this fact can only be
accounted for by the various races having similar inventive or
mental powers. The same observation has been made by
archaeologists*(3) with respect to certain widely-prevalent ornaments,
such as zig-zags, &c.; and with respect to various simple beliefs
and customs, such as the burying of the dead under megalithic
structures. I remember observing in South America,*(4) that there,
as in so many other parts of the world, men have generally chosen
the summits of lofty hills, to throw up piles of stones, either as a
record of some remarkable event, or for burying their dead.
* Tylor's Early History of Mankind, 1865: with respect to
gesture-language, see p. 54. Lubbock's Prehistoric Times, 2nd ed.,
1869.
*(2) "On Analogous Forms of Implements," in Memoirs of
Anthropological Society by H. M. Westropp. The Primitive Inhabitants
of Scandinavia, Eng. translat., edited by Sir J. Lubbock, 1868, p.
104.
*(3) Westropp "On Cromlechs," &c., Journal of Ethnological Soc.,
as given in Scientific Opinion, June 2, 1869, p. 3.
*(4) Journal of Researches: Voyage of the Beagle, p. 46.
Now when naturalists observe a close agreement in numerous small
details of habits, tastes, and dispositions between two or more
domestic races, or between nearly-allied natural forms, they use
this fact as an argument that they are descended from a common
progenitor who was thus endowed; and consequently that all should be
classed under the same species. The same argument may be applied
with much force to the races of man.
As it is improbable that the numerous and unimportant points of
resemblance between the several races of man in bodily structure and
mental faculties (I do not here refer to similar customs) should all
have been independently acquired, they must have been inherited from
progenitors who had these same characters. We thus gain some insight
into the early state of man, before he had spread step by step over
the face of the earth. The spreading of man to regions widely
separated by the sea, no doubt, preceded any great amount of
divergence of character in the several races; for otherwise we
should sometimes meet with the same race in distinct continents; and
this is never the case. Sir J. Lubbock, after comparing the arts now
practised by savages in all parts of the world, specifies those
which man could not have known, when he first wandered from his
original birthplace; for if once learnt they would never have been
forgotten.* He thus shews that "the spear, which is but a
development of the knife-point, and the club, which is but a long
hammer, are the only things left." He admits, however, that the art of
making fire probably had been already discovered, for it is common
to all the races now existing, and was known to the ancient
cave-inhabitants of Europe. Perhaps the art of making rude canoes or
rafts was likewise known; but as man existed at a remote epoch, when
the land in many places stood at a very different level to what it
does now, he would have been able, without the aid of canoes, to
have spread widely. Sir J. Lubbock further remarks how improbable it
is that our earliest ancestors could have "counted as high as ten,
considering that so many races now in existence cannot get beyond
four." Nevertheless, at this early period, the intellectual and social
faculties of man could hardly have been inferior in any extreme degree
to those possessed at present by the lowest savages; otherwise
primeval man could not have been so eminently successful in the
struggle for life, as proved by his early and wide diffusion.
* Prehistoric Times, 1869, p. 574.
From the fundamental differences between certain languages, some
philologists have inferred that when man first became widely diffused,
he was not a speaking animal; but it may be suspected that
languages, far less perfect than any now spoken, aided by gestures,
might have been used, and yet have left no traces on subsequent and
more highly-developed tongues. Without the use of some language,
however imperfect, it appears doubtful whether man's intellect could
have risen to the standard implied by his dominant position at an
early period.
Whether primeval man, when he possessed but few arts, and those of
the rudest kind, and when his power of language was extremely
imperfect, would have deserved to be called man, must depend on the
definition which we employ. In a series of forms graduating insensibly
from some ape-like creature to man as he now exists, it would be
impossible to fix on any definite point where the term "man" ought
to be used. But this is a matter of very little importance. So
again, it is almost a matter of indifference whether the so-called
races of man are thus designated, or are ranked as species or
sub-species; but the latter term appears the more appropriate.
Finally, we may conclude that when the principle of evolution is
generally accepted, as it surely will be before long, the dispute
between the monogenists and the polygenists will die a silent and
unobserved death.
One other question ought not to be passed over without notice,
namely, whether, as is sometimes assumed, each sub-species or race
of man has sprung from a single pair of progenitors. With our domestic
animals a new race can readily be formed by carefully matching the
varying offspring from a single pair, or even from a single individual
possessing some new character; but most of our races have been formed,
not intentionally from a selected pair, but unconsciously by the
preservation of many individuals which have varied, however
slightly, in some useful or desired manner. If in one country stronger
and heavier horses, and in another country lighter and fleeter ones,
were habitually preferred, we may feel sure that two distinct
sub-breeds would be produced in the course of time, without any one
pair having been separated and bred from, in either country. Many
races have been thus formed, and their manner of formation is
closely analogous to that of natural species. We know, also, that
the horses taken to the Falkland Islands have, during successive
generations, become smaller and weaker, whilst those which have run
wild on the Pampas have acquired larger and coarser heads; and such
changes are manifestly due, not to any one pair, but to all the
individuals having been subjected to the same conditions, aided,
perhaps, by the principle of reversion. The new sub-breeds in such
cases are not descended from any single pair, but from many
individuals which have varied in different degrees, but in the same
general manner; and we may conclude that the races of man have been
similarly produced, the modifications being either the direct result
of exposure to different conditions, or the indirect result of some
form of selection. But to this latter subject we shall presently
return.
On the Extinction of the Races of Man.- The partial or complete
extinction of many races and sub-races of man is historically known.
Humboldt saw in South America a parrot which was the sole living
creature that could speak a word of the language of a lost tribe.
Ancient monuments and stone implements found in all parts of the
world, about which no tradition has been preserved by the present
inhabitants, indicate much extinction. Some small and broken tribes,
remnants of former races, still survive in isolated and generally
mountainous districts. In Europe the ancient races were all, according
to Shaaffhausen,* "lower in the scale than the rudest living savages";
they must therefore have differed, to a certain extent, from any
existing race. The remains described by Professor Broca from Les
Eyzies, though they unfortunately appear to have belonged to a
single family, indicate a race with a most singular combination of low
or simious, and of high characteristics. This race is "entirely
different from any other, ancient or modern, that we have heard
of."*(2) It differed, therefore, from the quaternary race of the
caverns of Belgium.
* Translation in Anthropological Review, Oct., 1868, p. 431.
*(2) Transactions, International Congress of Prehistoric Archaeology
1868, pp. 172-175. See also Broca (tr.) in Anthropological Review,
Oct., 1868, p. 410.
Man can long resist conditions which appear extremely unfavourable
for his existence.* He has long lived in the extreme regions of the
North, with no wood for his canoes or implements, and with only
blubber as fuel, and melted snow as drink. In the southern extremity
of America the Fuegians survive without the protection of clothes,
or of any building worthy to be called a hovel. In South Africa the
aborigines wander over arid plains, where dangerous beasts abound. Man
can withstand the deadly influence of the Terai at the foot of the
Himalaya, and the pestilential shores of tropical Africa.
* Dr. Gerland, Uber das Aussterben der Naturvolker 1868, s. 82.
Extinction follows chiefly from the competition of tribe with tribe,
and race with race. Various checks are always in action, serving to
keep down the numbers of each savage tribe,- such as periodical
famines, nomadic habits and the consequent deaths of infants,
prolonged suckling, wars, accidents, sickness, licentiousness, the
stealing of women, infanticide, and especially lessened fertility.
If any one of these checks increases in power, even slightly, the
tribe thus affected tends to decrease; and when of two adjoining
tribes one becomes less numerous and less powerful than the other, the
contest is soon settled by war, slaughter, cannibalism, slavery, and
absorption. Even when a weaker tribe is not thus abruptly swept
away, if it once begins to decrease, it generally goes on decreasing
until it becomes extinct.*
* Gerland, ibid., s. 12, gives facts in support of this statement.
When civilised nations come into contact with barbarians the
struggle is short, except where a deadly climate gives its aid to
the native race. Of the causes which lead to the victory of
civilised nations, some are plain and simple, others complex and
obscure. We can see that the cultivation of the land will be fatal
in many ways to savages, for they cannot, or will not, change their
habits. New diseases and vices have in some cases proved highly
destructive; and it appears that a new disease often causes much
death, until those who are most susceptible to its destructive
influence are gradually weeded out;* and so it may be with the evil
effects from spirituous liquors, as well as with the unconquerably
strong taste for them shewn by so many savages. It further appears,
mysterious as is the fact, that the first meeting of distinct and
separated people generates disease.*(2) Mr. Sproat, who in Vancouver
Island closely attended to the subject of extinction, believed that
changed habits of life, consequent on the advent of Europeans, induces
much ill health. He lays, also, great stress on the apparently
trifling cause that the natives become "bewildered and dull by the new
life around them; they lose the motives for exertion, and get no new
ones in their place."*(3)
* See remarks to this effect in Sir H. Holland's Medical Notes and
Reflections, 1839, p. 390.
*(2) I have collected (Journal of Researches: Voyage of the
Beagle, p. 435) a good many cases bearing on this subject; see also
Gerland, ibid., s. 8. Poeppig speaks of the "breath of civilisation as
poisonous to savages."
*(3) Sproat, Scenes and Studies of Savage Life, 1868, p. 284.
The grade of their civilisation seems to be a most important element
in the success of competing nations. A few centuries ago Europe feared
the inroads of Eastern barbarians; now any such fear would be
ridiculous. It is a more curious fact, as Mr. Bagehot has remarked,
that savages did not formerly waste away before the classical nations,
as they now do before modern civilised nations; had they done so,
the old moralists would have mused over the event; but there is no
lament in any writer of that period over the perishing barbarians.*
The most potent of all the causes of extinction, appears in many cases
to be lessened fertility and ill-health, especially amongst the
children, arising from changed conditions of life, notwithstanding
that the new conditions may not be injurious in themselves. I am
much indebted to Mr. H. H. Howorth for having called my attention
to this subject, and for having given me information respecting it.
I have collected the following cases.
* Bagehot, "Physics and Politics," Fortnightly Review, April 1,
1868, p. 455.
When Tasmania was first colonised the natives were roughly estimated
by some at 7000 and by others at 20,000. Their number was soon greatly
reduced, chiefly by fighting with the English and with each other.
After the famous hunt by all the colonists, when the remaining natives
delivered themselves up to the government, they consisted only of
120 individuals,* who were in 1832 transported to Flinders Island.
This island, situated between Tasmania and Australia, is forty miles
long, and from twelve to eighteen miles broad: it seems healthy, and
the natives were well treated. Nevertheless, they suffered greatly
in health. In 1834 they consisted (Bonwick, p. 250) of forty-seven
adult males, forty-eight adult females, and sixteen children, or in
all of 111 souls. In 1835 only one hundred were left. As they
continued rapidly to decrease, and as they themselves thought that
they should not perish so quickly elsewhere, they were removed in 1847
to Oyster Cove in the southern part of Tasmania. They then consisted
(Dec. 20th, 1847) of fourteen men, twenty-two women and ten
children.*(2) But the change of site did no good. Disease and death
still pursued them, and in 1864 one man (who died in 1869), and
three elderly women alone survived. The infertility of the women is
even a more remarkable fact than the liability of all to ill-health
and death. At the time when only nine women were left at Oyster
Cove, they told Mr. Bonwick (p. 386), that only two had ever borne
children: and these two had together produced only three children!
* All the statements here given are taken from The Last of the
Tasmanians, by J. Bonwick, 1870.
*(2) This is the statement of the Governor of Tasmania, Sir W.
Denison, Varieties of Vice-Regal Life, 1870, vol. i., p. 67.
With respect to the cause of this extraordinary state of things, Dr.
Story remarks that death followed the attempts to civilise the
natives. "If left to themselves to roam as they were wont and
undisturbed, they would have reared more children, and there would
have been less mortality." Another careful observer of the natives,
Mr. Davis, remarks, "The births have been few and the deaths numerous.
This may have been in a great measure owing to their change of
living and food; but more so to their banishment from the mainland
of Van Diemen's Land, and consequent depression of spirits"
(Bonwick, pp. 388, 390).
Similar facts have been observed in two widely different parts of
Australia. The celebrated explorer, Mr. Gregory, told Mr. Bonwick,
that in Queensland "the want of reproduction was being already felt
with the blacks, even in the most recently settled parts, and that
decay would set in." Of thirteen aborigines from Shark's Bay who
visited Murchison River, twelve died of consumption within three
months.*
* For these cases, see Bonwick's Daily Life of the Tasmanians, 1870,
p. 90: and The Last of the Tasmanians, 1870, p. 386.
The decrease of the Maories of New Zealand has been carefully
investigated by Mr. Fenton, in an admirable report, from which all the
following statements, with one exception, are taken.* The decrease
in number since 1830 is admitted by every one, including the natives
themselves, and is still steadily progressing. Although it has
hitherto been found impossible to take an actual census of the
natives, their numbers were carefully estimated by residents in many
districts. The result seems trustworthy, and shows that during the
fourteen years, previous to 1858, the decrease was 19.42 per cent.
Some of the tribes, thus carefully examined, lived above a hundred
miles apart, some on the coast, some inland; and their means of
subsistence and habits differed to a certain extent (p. 28). The total
number in 1858 was believed to be 53,700, and in 1872, after a
second interval of fourteen years, another census was taken, and the
number is given as only 36,359, shewing a decrease of 32.29 per
cent!*(2) Mr. Fenton, after shewing in detail the insufficiency of the
various causes, usually assigned in explanation of this
extraordinary decrease, such as new diseases, the profligacy of the
women, drunkenness, wars, &c., concludes on weighty grounds that it
depends chiefly on the unproductiveness of the women, and on the
extraordinary mortality of the young children (pp. 31, 34). In proof
of this he shews (p. 33) that in 1844 there was one non-adult for
every 2.57 adults; whereas in 1858 there was only one non-adult for
every 3.27 adults. The mortality of the adults is also great. He
adduces as a further cause of the decrease the inequality of the
sexes; for fewer females are born than males. To this latter point,
depending perhaps on a widely distinct cause, I shall return in a
future chapter. Mr. Fenton contrasts with astonishment the decrease in
New Zealand with the increase in Ireland; countries not very
dissimilar in climate, and where the inhabitants now follow nearly
similar habits. The Maories themselves (p. 35) "attribute their
decadence, in some measure, to the introduction of new food and
clothing, and the attendant change of habits"; and it will be seen,
when we consider the influence of changed conditions on fertility,
that they are probably right. The diminution began between the years
1830 and 1840; and Mr. Fenton shews (p. 40) that about 1830, the art
of manufacturing putrid corn (maize), by long steeping in water, was
discovered and largely practised; and this proves that a change of
habits was beginning amongst the natives, even when New Zealand was
only thinly inhabited by Europeans. When I visited the Bay of
Islands in 1835, the dress and food of the inhabitants had already
been much modified: they raised potatoes, maize, and other
agricultural produce, and exchanged them for English manufactured
goods and tobacco.
* Observations on the Aboriginal Inhabitants of New Zealand,
published by the Government, 1859.
*(2) New Zealand, by Alex. Kennedy, 1873, p. 47.
It is evident from many statements in the life of Bishop
Patteson,* that the Melanesians of the New Hebrides and neighbouring
archipelagoes, suffered to an extraordinary degree in health, and
perished in large numbers, when they were removed to New Zealand,
Norfolk Island, and other salubrious places, in order to be educated
as missionaries.
* Life of J. C. Patteson, by C. M. Younge, 1874; see more especially
vol. i., p. 530.
The decrease of the native population of the Sandwich Islands is
as notorious as that of New Zealand. It has been roughly estimated
by those best capable of judging, that when Cook discovered the
islands in 1779, the population amounted to about 300,000. According
to a loose census in 1823, the numbers then were 142,050. In 1832, and
at several subsequent periods, an accurate census was officially
taken, but I have been able to obtain only the following returns:
Native Population Annual rate of decrease
per cent, assuming it to
(Except during 1832 and have been uniform between
1836, when the few the successive censuses;
foreigners in the islands these censuses being taken
Year were included.) at irregular intervals.
1832 130,313
4.46
1836 108,579
2.47
1853 71,019
0.81
1860 67,084
2.18
1866 58,765
2.17
1872 51,531
We here see that in the interval of forty years, between 1832 and
1872, the population has decreased no less than sixty-eight per
cent! This has been attributed by most writers to the profligacy of
the women, to former bloody wars, and to the severe labour imposed
on conquered tribes and to newly introduced diseases, which have
been on several occasions extremely destructive. No doubt these and
other such causes have been highly efficient, and may account for
the extraordinary rate of decrease between the years 1832 and 1836;
but the most potent of all the causes seems to be lessened
fertility. According to Dr. Ruschenberger of the U. S. Navy, who
visited these islands between 1835 and 1837, in one district of
Hawaii, only twenty-five men out of 1134, and in another district only
ten out of 637, had a family with as many as three children. Of eighty
married women, only thirty-nine had ever borne children; and "the
official report gives an average of half a child to each married
couple in the whole island." This is almost exactly the same average
as with the Tasmanians at Oyster Cove. Jarves, who published his
History in 1843, says that "families who have three children are freed
from all taxes; those having more, are rewarded by gifts of land and
other encouragements." This unparalleled enactment by the government
well shews how infertile the race had become. The Rev. A. Bishop
stated in the Hawaiian Spectator in 1839, that a large proportion of
the children die at early ages, and Bishop Staley informs me that this
is still the case, just as in New Zealand. This has been attributed to
the neglect of the children by the women, but it is probably in
large part due to innate weakness of constitution in the children,
in relation to the lessened fertility of their parents. There is,
moreover, a further resemblance to the case of New Zealand, in the
fact that there is a large excess of male over female births: the
census of 1872 gives 31,650 males to 25,247 females of all ages,
that is 125.36 males for every 100 females; whereas in all civilised
countries the females exceed the males. No doubt the profligacy of the
women may in part account for their small fertility; but their changed
habits of life is a much more probable cause, and which will at the
same time account for the increased mortality, especially of the
children. The islands were visited by Cook in 1779, Vancouver in 1794,
and often subsequently by whalers. In 1819 missionaries arrived, and
found that idolatry had been already abolished and other changes
effected by the king. After this period there was a rapid change in
almost all the habits of life of the natives, and they soon became
"the most civilised of the Pacific Islanders." One of my informants,
Mr. Coan, who was born on the islands, remarks that the natives have
undergone a greater change in their habits of life in the course of
fifty years than Englishmen during a thousand years. From
information received from Bishop Staley, it does not appear that the
poorer classes have ever much changed their diet, although many new
kinds of fruit have been introduced, and the sugar-cane is in
universal use. Owing, however, to their passion for imitating
Europeans, they altered their manner of dressing at an early period,
and the use of alcoholic drinks became very general. Although these
changes appear inconsiderable, I can well believe, from what is
known with respect to animals, that they might suffice to lessen the
fertility of the natives.*
* The foregoing statements are taken chiefly from the following
works: Jarves' History of the Hawaiian Islands, 1843, pp. 400-407.
Cheever, Life in the Sandwich Islands, 1851, p. 277. Ruschenberger
is quoted by Bonwick, Last of the Tasmanians, 1870, p. 378. Bishop
is quoted by Sir E. Belcher, Voyage Round the World, 1843, vol. i., p.
272. I owe the census of the several years to the kindness of Mr.
Coan, at the request of Dr. Youmans of New York; and in most cases I
have compared the Youmans figures with those given in several of the
above-named works. I have omitted the census for 1850, as I have
seen two widely different numbers given.
Lastly, Mr. Macnamara states* that the low and degraded
inhabitants of the Andaman Islands, on the eastern side of the Gulf of
Bengal, are "eminently susceptible to any change of climate: in
fact, take them away from their island homes, and they are almost
certain to die, and that independently of diet or extraneous
influences." He further states that the inhabitants of the Valley of
Nepal, which is extremely hot in summer, and also the various
hill-tribes of India, suffer from dysentery and fever when on the
plains; and they die if they attempt to pass the whole year there.
* The Indian Medical Gazette, Nov. 1, 1871, p. 240.
We thus see that many of the wilder races of man are apt to suffer
much in health when subjected to changed conditions or habits of life,
and not exclusively from being transported to a new climate. Mere
alterations in habits, which do not appear injurious in themselves,
seem to have this same effect; and in several cases the children are
particularly liable to suffer. It has often been said, as Mr.
Macnamara remarks, that man can resist with impunity the greatest
diversities of climate and other changes; but this is true only of the
civilised races. Man in his wild condition seems to be in this respect
almost as susceptible as his nearest allies, the anthropoid apes,
which have never yet survived long, when removed from their native
country.
Lessened fertility from changed conditions, as in the case of the
Tasmanians, Maories, Sandwich Islanders, and apparently the
Australians, is still more interesting than their liability to
ill-health and death; for even a slight degree of infertility,
combined with those other causes which tend to check the increase of
every population, would sooner or later lead to extinction. The
diminution of fertility may be explained in some cases by the
profligacy of the women (as until lately with the Tahitians), but
Mr. Fenton has shewn that this explanation by no means suffices with
the New Zealanders, nor does it with the Tasmanians.
In the paper above quoted, Mr. Macnamara gives reasons for believing
that the inhabitants of districts subject to malaria are apt to be
sterile; but this cannot apply in several of the above cases. Some
writers have suggested that the aborigines of islands have suffered in
fertility and health from long continued interbreeding; but in the
above cases infertility has coincided too closely with the arrival
of Europeans for us to admit this explanation. Nor have we at
present any reason to believe that man is highly sensitive to the evil
effects of inter-breeding, especially in areas so large as New
Zealand, and the Sandwich archipelago with its diversified stations.
On the contrary, it is known that the present inhabitants of Norfolk
Island are nearly all cousins or near relations, as are the Todas in
India, and the inhabitants of some of the Western Islands of Scotland;
and yet they seem not to have suffered in fertility.*
* On the close relationship of the Norfolk Islanders, Sir W.
Denison, Varieties of Vice-Regal Life: vol. i., 1870, p. 410. For
the Todas, see Col. Marshall's work 1873, p. 110. For the Western
Islands of Scotland, Dr. Mitchell, Edinburgh Medical Journal, March to
June, 1865.
A much more probable view is suggested by the analogy of the lower
animals. The reproductive system can be shewn to be susceptible to
an extraordinary degree (though why we know not) to changed conditions
of life; and this susceptibility leads both to beneficial and to
evil results. A large collection of facts on this subject is given
in chap. xviii. of vol. ii. of my Variation of Animals and Plants
under Domestication, I can here give only the briefest abstract; and
every one interested in the subject may consult the above work. Very
slight changes increase the health, vigour, and fertility of most or
all organic beings, whilst other changes are known to render a large
number of animals sterile. One of the most familiar cases, is that
of tamed elephants not breeding in India; though they often breed in
Ava, where the females are allowed to roam about the forests to some
extent, and are thus placed under more natural conditions. The case of
various American monkeys, both sexes of which have been kept for
many years together in their own countries, and yet have very rarely
or never bred, is a more apposite instance, because of their
relationship to man. It is remarkable how slight a change in the
conditions often induces sterility in a wild animal when captured; and
this is the more strange as all our domesticated animals have become
more fertile than they were in a state of nature; and some of them can
resist the most unnatural conditions with undiminished fertility.*
Certain groups of animals are much more liable than others to be
affected by captivity; and generally all the species of the same group
are affected in the same manner. But sometimes a single species in a
group is rendered sterile, whilst the others are not so; on the
other hand, a single species may retain its fertility whilst most of
the others fail to breed. The males and females of some species when
confined, or when allowed to live almost, but not quite free, in their
native country, never unite; others thus circumstanced frequently
unite but never produce offspring; others again produce some
offspring, but fewer than in a state of nature; and as bearing on
the above cases of man, it is important to remark that the young are
apt to be weak and sickly, or malformed, and to perish at an early
age.
* For the evidence on this head, see Variation of Animals, &c., vol.
ii., p. 111.
Seeing how general is this law of the susceptibility of the
reproductive system to changed conditions of life, and that it holds
good with our nearest allies, the Quadrumana, I can hardly doubt
that it applies to man in his primeval state. Hence if savages of
any race are induced suddenly to change their habits of life, they
become more or less sterile, and their young offspring suffer in
health, in the same manner and from the same cause, as do the elephant
and hunting-leopard in India, many monkeys in America, and a host of
animals of all kinds, on removal from their natural conditions.
We can see why it is that aborigines, who have long inhabited
islands, and who must have been long exposed to nearly uniform
conditions, should be specially affected by any change in their
habits, as seems to be the case. Civilised races can certainly
resist changes of all kinds far better than savages; and in this
respect they resemble domesticated animals, for though the latter
sometimes suffer in health (for instance European dogs in India),
yet they are rarely rendered sterile, though a few such instances have
been recorded.* The immunity of civilised races and domesticated
animals is probably due to their having been subjected to a greater
extent, and therefore having grown somewhat more accustomed, to
diversified or varying conditions, than the majority of wild
animals; and to their having formerly immigrated or been carried
from country to country, and to different families or subraces
having inter-crossed. It appears that a cross with civilised races
at once gives to an aboriginal race an immunity from the evil
consequences of changed conditions. Thus the crossed offspring from
the Tahitians and English, when settled in Pitcairn Island,
increased so rapidly that the island was soon overstocked; and in June
1856 they were removed to Norfolk Island. They then consisted of 60
married persons and 134 children, making a total of 194. Here they
likewise increased so rapidly, that although sixteen of them
returned to Pitcairn Island in 1859, they numbered in January 1868,
300 souls; the males and females being in exactly equal numbers.
What a contrast does this case present with that of the Tasmanians;
the Norfolk Islanders increased in only twelve and a half years from
194 to 300; whereas the Tasmanians decreased during fifteen years from
120 to 46, of which latter number only ten were children.*(2)
* Variation of Animals, &c., vol. ii., p. 16.
*(2) These details are taken from The Mutineers of the Bounty, by
Lady Belcher, 1870; and from Pitcairn Island, ordered to be printed by
the House of Commons, May 29, 1863. The following statements about the
Sandwich Islanders are from the Honolulu Gazette, and from Mr. Coan.
So again in the interval between the census of 1866 and 1872 the
natives of full blood in the Sandwich Islands decreased by 8081,
whilst the half-castes, who are believed to be healthier, increased by
847; but I do not know whether the latter number includes the
offspring from the half-castes, or only the half-castes of the first
generation.
The cases which I have here given all relate to aborigines, who have
been subjected to new conditions as the result of the immigration of
civilised men. But sterility and ill-health would probably follow,
if savages were compelled by any cause, such as the inroad of a
conquering tribe, to desert their homes and to change their habits. It
is an interesting circumstance that the chief check to wild animals
becoming domesticated, which implies the power of their breeding
freely when first captured, and one chief check to wild men, when
brought into contact with civilisation, surviving to form a
civilised race, is the same, namely, sterility from changed conditions
of life.
Finally, although the gradual decrease and ultimate extinction of
the races of man is a highly complex problem, depending on many causes
which differ in different places and at different times; it is the
same problem as that presented by the extinction of one of the
higher animals- of the fossil horse, for instance, which disappeared
from South America, soon afterwards to be replaced, within the same
districts, by countless troups of the Spanish horse. The New Zealander
seems conscious of this parallelism, for he compares his future fate
with that of the native rat now almost exterminated by the European
rat. Though the difficulty is great to our imagination, and really
great, if we wish to ascertain the precise causes and their manner
of action, it ought not to be so to our reason, as long as we keep
steadily in mind that the increase of each species and each race is
constantly checked in various ways; so that if any new check, even a
slight one, be superadded, the race will surely decrease in number;
and decreasing numbers will sooner or later lead to extinction; the
end, in most cases, being promptly determined by the inroads of
conquering tribes.
On the Formation of the Races of Man.- In some cases the crossing of
distinct races has led to the formation of a new race. The singular
fact that the Europeans and Hindoos, who belong to the same Aryan
stock, and speak a language fundamentally the same, differ widely in
appearance, whilst Europeans differ but little from Jews, who belong
to the Semitic stock, and speak quite another language, has been
accounted for by Broca,* through certain Aryan branches having been
largely crossed by indigenous tribes during their wide diffusion. When
two races in close contact cross, the first result is a
heterogeneous mixture: thus Mr. Hunter, in describing the Santali or
hill-tribes of India, says that hundreds of imperceptible gradations
may be traced "from the black, squat tribes of the mountains to the
tall olive-coloured Brahman, with his intellectual brow, calm eyes,
and high but narrow head"; so that it is necessary in courts of
justice to ask the witnesses whether they are Santalis or Hindoos.*(2)
Whether a heterogeneous people, such as the inhabitants of some of the
Polynesian islands, formed by the crossing of two distinct races, with
few or no pure members left, would ever become homogeneous, is not
known from direct evidence. But as with our domesticated animals, a
cross-breed can certainly be fixed and made uniform by careful
selection*(3) in the course of a few generations, we may infer that
the free inter-crossing of a heterogeneous mixture during a long
descent would supply the place of selection, and overcome any tendency
to reversion; so that the crossed race would ultimately become
homogeneous, though it might not partake in an equal degree of the
characters of the two parent-races.
* "On Anthropology," translation, Anthropological Review, Jan.,
1868, p. 38.
*(2) The Animals of Rural Bengal, 1868, p. 134.
*(3) The Variation of Animals and Plants under Domestication vol.
ii., p. 95.
Of all the differences between the races of man, the colour of the
skin is the most conspicuous and one of the best marked. It was
formerly thought that differences of this kind could be accounted
for by long exposure to different climates; but Pallas first shewed
that this is not tenable, and he has since been followed by almost all
anthropologists.* This view has been rejected chiefly because the
distribution of the variously coloured races, most of whom have long
inhabited their present homes, does not coincide with corresponding
differences of climate. Some little weight may be given to such
cases as that of the Dutch families, who, as we hear on excellent
authority,*(2) have not undergone the least change of colour after
residing for three centuries in South Africa. An argument on the
same side may likewise be drawn from the uniform appearance in various
parts of the world of gipsies and Jews, though the uniformity of the
latter has been somewhat exaggerated.*(3) A very damp or a very dry
atmosphere has been supposed to be more influential in modifying the
colour of the skin than mere heat; but as D'Orbigny in South
America, and Livingstone in Africa, arrived at diametrically
opposite conclusions with respect to dampness and dryness, any
conclusion on this head must be considered as very doubtful.*(4)
* Pallas, Act. Acad. St. Petersburg, 1780, part ii., p. 69. He was
followed by Rudolphi, in his Beitrage zur Anthropologie, 1812. An
excellent summary of the evidence is given by Godron, De l'Espece,
1859, vol. ii., p. 246, &c.
*(2) Sir Andrew Smith, as quoted by Knox, Races of Man, 1850, p.
473.
*(3) See De Quatrefages on this head, Revue des Cours Scientifiques,
Oct. 17, 1868, p. 731.
*(4) Livingstone's Travels and Researches in S. Africa, 1857, pp.
338, 339. D'Orbigny, as quoted by Godron, De l'Espece, vol. ii., p.
266.
Various facts, which I have given elsewhere, prove that the colour
of the skin and hair is sometimes correlated in a surprising manner
with a complete immunity from the action of certain vegetable poisons,
and from the attacks of certain parasites. Hence it occurred to me,
that negroes and other dark races might have acquired their dark tints
by the darker individuals escaping from the deadly influence of the
miasma of their native countries, during a long series of generations.
I afterwards found that this same idea had long ago occurred to
Dr. Wells.* It has long been known that negroes, and even mulattoes
are almost completely exempt from the yellow fever, so destructive
in tropical America.*(2) They likewise escape to a large extent the
fatal intermittent fevers, that prevail along at least 2600 miles of
the shores of Africa, and which annually cause one-fifth of the
white settlers to die, and another fifth to return home invalided.*(3)
This immunity in the negro seems to be partly inherent, depending on
some unknown peculiarity of constitution, and partly the result of
acclimatisation. Pouchet*(4) states that the negro regiments recruited
near the Soudan, and borrowed from the Viceroy of Egypt for the
Mexican war, escaped the yellow fever almost equally with the
negroes originally brought from various parts of Africa and accustomed
to the climate of the West Indies. That acclimatisation plays a
part, is shewn by the many cases in which negroes have become somewhat
liable to tropical fevers, after having resided for some time in a
colder climate.*(5) The nature of the climate under which the white
races have long resided likewise has some influence on them; for
during the fearful epidemic of yellow fever in Demerara during 1837,
Dr. Blair found that the death-rate of the immigrants was proportional
to the latitude of the country whence they had come. With the negro
the immunity, as far as it is the result of acclimatisation, implies
exposure during a prodigious length of time; for the aborigines of
tropical America who have resided there from time immemorial, are
not exempt from yellow fever; and the Rev. H. B. Tristram states, that
there are districts in nothern Africa which the native inhabitants are
compelled annually to leave, though the negroes can remain with
safety.
* See a paper read before the Royal Soc. in 1813, and published in
his Essays in 1818. I have given an account of Dr. Wells' views in the
"Historical Sketch" (p. 2) to my Origin of Species. Various cases of
colour correlated with constitutional peculiarities are given in my
Variation of Animals and Plants under Domestication, vol. ii., pp.
227, 335.
*(2) See, for instance, Nott and Gliddon, Types of Mankind, p. 68.
*(3) Major Tulloch in a paper read before the Statistical Society,
April 20, 1840, and given in the Athenaeum, 1840, p. 353.
*(4) The Plurality of the Human Race (translat.), 1864, p. 60.
*(5) Quartrefages, Unite de l'Espece Humaine, 1861, p. 205. Wartz,
Introduction to Anthropology, translat., vol. i., 1863, p. 124.
Livingstone gives analogous cases in his Travels.
That the immunity of the negro is in any degree correlated with
the colour of his skin is a mere conjecture: it may be correlated with
some difference in his blood, nervous system, or other tissues.
Nevertheless, from the facts above alluded to, and from some
connection apparently existing between complexion and a tendency to
consumption, the conjecture seemed to me not improbable.
Consequently I endeavoured, with but little success,* to ascertain how
far it holds good. The late Dr. Daniell, who had long lived on the
west coast of Africa, told me that he did not believe in any such
relation. He was himself unusually fair, and had withstood the climate
in a wonderful manner. When he first arrived as a boy on the coast, an
old and experienced negro chief predicted from his appearance that
this would prove the case. Dr. Nicholson, of Antigua, after having
attended to this subject, writes to me that dark-coloured Europeans
escape the yellow fever more than those that are light-coloured. Mr.
J. M. Harris altogether denies that Europeans with dark hair withstand
a hot climate better than other men: on the contrary, experience has
taught him in making a selection of men for service on the coast of
Africa, to choose those with red hair.*(2) As far, therefore, as these
slight indications go, there seems no foundation for the hypothesis,
that blackness has resulted from the darker and darker individuals
having survived better during long exposure to fever-generating
miasma.
* In the spring of 1862 I obtained permission from the
Director-General of the Medical department of the Army, to transmit to
the surgeons of the various regiments on foreign service a blank
table, with the following appended remarks, but I have received no
returns. "As several well-marked cases have been recorded with our
domestic animals of a relation between the colour of the dermal
appendages and the constitution; and it being notorious that there
is some limited degree of relation between the colour of the races
of man and the climate inhabited by them; the following
investigation seems worth consideration. Namely, whether there is
any relation in Europeans between the colour of their hair, and
their liability to the diseases of tropical countries. If the surgeons
of the several regiments, when stationed in unhealthy tropical
districts, would be so good as first to count, as a standard of
comparison, how many men, in the force whence the sick are drawn, have
dark and light-coloured hair, and hair of intermediate or doubtful
tints; and if a similar account were kept by the same medical
gentlemen, of all the men who suffered from malarious and yellow
fevers, or from dysentery, it would soon be apparent, after some
thousand cases had been tabulated, whether there exists any relation
between the colour of the hair and constitutional liability to
tropical diseases. Perhaps no such relation would be discovered, but
the investigation is well worth making. In case any positive result
were obtained, it might be of some practical use in selecting men
for any particular service. Theoretically the result would be of
high interest, as indicating one means by which a race of men
inhabiting from a remote period an unhealthy tropical climate, might
have become dark-coloured by the better preservation of dark-haired or
dark-complexioned individuals during a long succession of
generations."
*(2) Anthropological Review, Jan., 1866, p. xxi. Dr. Sharpe also
says, with respect to India (Man a Special Creation, 1873, p. 118),
"that it has been noticed by some medical officers that Europeans with
light hair and florid complexions suffer less from diseases of
tropical countries than persons with dark hair and sallow complexions;
and, so far as I know, there appear to be good grounds for this
remark." On the other hand, Mr. Heddle, of Sierra Leone, "who has
had more clerks killed under him than any other man," by the climate
of the west African coast (W. Reade, African Sketch Book, vol. ii., p.
522), holds a directly opposite view, as does Capt. Burton.
Dr. Sharpe remarks,* that a tropical sun, which burns and blisters a
white skin, does not injure a black one at all; and, as he adds,
this is not due to habit in the individual, for children only six or
eight months old are often carried about naked, and are not
affected. I have been assured by a medical man, that some years ago
during each summer, but not during the winter, his hands became marked
with light brown patches, like, although larger than freckles, and
that these patches were never affected by sun-burning, whilst the
white parts of his skin have on several occasions been much inflamed
and blistered. With the lower animals there is, also, a constitutional
difference in liability to the action of the sun between those parts
of the skin clothed with white hair and other parts.*(2) Whether the
saving of the skin from being thus burnt is of sufficient importance
to account for a dark tint having been gradually acquired by man
through natural selection, I am unable to judge. If it be so, we
should have to assume that the natives of tropical America have
lived there for a much shorter time than the Negroes in Africa or
the Papuans in the southern parts of the Malay archipelago, just as
the lighter-coloured Hindoos have resided in India for a shorter
time than the darker aborigines of the central and southern parts of
the peninsula.
* Man a Special Creation, 1873, p. 119.
*(2) Variation of Animals and Plants under Domestication, vol.
ii., pp. 336, 337.
Although with our present knowledge we cannot account for the
differences of colour in the races of man, through any advantage
thus gained, or from the direct action of climate; yet we must not
quite ignore the latter agency, for there is good reason to believe
that some inherited effect is thus produced.*
* See, for instance, Quatrefages (Revue des Cours Scientifiques,
Oct. 10, 1868, p. 724) on the effects of residence in Abyssinia and
Arabia, and other analogous cases. Dr. Rolle (Der Mensch, seine
Abstammung, &c., 1865, s. 99) states, on the authority of Khanikof,
that the greater number of German families settled in Georgia, have
acquired in the course of two generations dark hair and eyes. Mr. D.
Forbes informs me that the Quechuas in the Andes vary greatly in
colour, according to the position of the valleys inhabited by them.
We have seen in the second chapter that the conditions of life
affect the development of the bodily frame in a direct manner, and
that the effects are transmitted. Thus, as is generally admitted,
the European settlers in the United States undergo a slight but
extraordinary rapid change of appearance. Their bodies and limbs
become elongated; and I hear from Col. Bernys that during the late war
in the United States, good evidence was afforded of this fact by the
ridiculous appearance presented by the German regiments, when
dressed in ready-made clothes manufactured for the American market,
and which were much too long for the men in every way. There is, also,
a considerable body of evidence shewing that in the Southern States
the house-slaves of the third generation present a markedly
different appearance from the field-slaves.*
* Harlan, Medical Researches, p. 532. Quatrefages (Unite de l'Espece
Humaine, 1861, p. 128) has collected much evidence on this head.
If, however, we look to the races of man as distributed over the
world, we must infer that their characteristic differences cannot be
accounted for by the direct action of different conditions of life,
even after exposure to them for an enormous period of time. The
Esquimaux live exclusively on animal food; they are clothed in thick
fur, and are exposed to intense cold and to prolonged darkness; yet
they do not differ in any extreme degree from the inhabitants of
southern China, who live entirely on vegetable food, and are exposed
almost naked to a hot, glaring climate. The unclothed Fuegians live on
the marine productions of their inhospitable shores; the Botocudos
of Brazil wander about the hot forests of the interior and live
chiefly on vegetable productions; yet these tribes resemble each other
so closely that the Fuegians on board the "Beagle" were mistaken by
some Brazilians for Botocudos. The Botocudos again, as well as the
other inhabitants of tropical America, are wholly different from the
Negroes who inhabit the opposite shores of the Atlantic, are exposed
to a nearly similar climate, and follow nearly the same habits of
life.
Nor can the differences between the races of man be accounted for by
the inherited effects of the increased or decreased use of parts,
except to a quite insignificant degree. Men who habitually live in
canoes, may have their legs somewhat stunted; those who inhabit
lofty regions may have their chests enlarged; and those who constantly
use certain sense-organs may have the cavities in which they are
lodged somewhat increased in size, and their features consequently a
little modified. With civilized nations, the reduced size of the
jaws from lessened use- the habitual play of different muscles serving
to express different emotions- and the increased size of the brain
from greater intellectual activity, have together produced a
considerable effect on their general appearance when compared with
savages.* Increased bodily stature, without any corresponding increase
in the size of the brain, may (judging from the previously adduced
case of rabbits), have given to some races an elongated skull of the
dolichocephalic type.
* See Prof. Schaaffhausen, translat., in Anthropological Review,
Oct., 1868, p. 429.
Lastly, the little-understood principle of correlated development
has sometimes come into action, as in the case of great muscular
development and strongly projecting supra-orbital ridges. The colour
of the skin and hair are plainly correlated, as is the texture of
the hair with its colour in the Mandans of North America.* The
colour also of the skin, and the odour emitted by it, are likewise
in some manner connected. With the breeds of sheep the number of hairs
within a given space and the number of excretory pores are
related.*(2) If we may judge from the analogy of our domesticated
animals, many modifications of structure in man probably come under
this principle of correlated development.
* Mr. Catlin states (N. American Indians, 3rd ed., 1842, vol. i., p.
49) that in the whole tribe of the Mandans, about one in ten or twelve
of the members, of all ages and both sexes, have bright silvery grey
hair, which is hereditary. Now this hair is as coarse and harsh as
that of a horse's mane, whilst the hair of other colours is fine and
soft.
*(2) On the odour of the skin, Godron, De l'Espece, tom. ii., p.
217. On the pores of the skin, Dr. Wilckens, Die Aufgaben der
Landwirth. Zootechnik, 1869, s. 7.
We have now seen that the external characteristic differences
between the races of man cannot be accounted for in a satisfactory
manner by the direct action of the conditions of life, nor by the
effects of the continued use of parts, nor through the principle of
correlation. We are therefore led to enquire whether slight individual
differences, to which man is eminently liable, may not have been
preserved and augmented during a long series of generations through
natural selection. But here we are at once met by the objection that
beneficial variations alone can be thus preserved; and as far as we
are enabled to judge, although always liable to err on this head, none
of the differences between the races of man are of any direct or
special service to him. The intellectual and moral or social faculties
must of course be excepted from this remark. The great variability
of all the external differences between the races of man, likewise
indicates that they cannot be of much importance; for if important,
they would long ago have been either fixed and preserved, or
eliminated. In this respect man resembles those forms, called by
naturalists protean or polymorphic, which have remained extremely
variable, owing, as it seems, to such variations being of an
indifferent nature, and to their having thus escaped the action of
natural selection.
We have thus far been baffled in all our attempts to account for the
differences between the races of man; but there remains one
important agency, namely Sexual Selection, which appears to have acted
powerfully on man, as on many other animals. I do not intend to assert
that sexual selection will account for all the differences between the
races. An unexplained residuum is left, about which we can only say,
in our ignorance, that as individuals are continually born with, for
instance, heads a little rounder or narrower, and with noses a
little longer or shorter, such slight differences might become fixed
and uniform, if the unknown agencies which induced them were to act in
a more constant manner, aided by long-continued intercrossing. Such
variations come under the provisional class, alluded to in our
second chapter, which for want of a better term are often called
spontaneous. Nor do I pretend that the effects of sexual selection can
be indicated with scientific precision; but it can be shewn that it
would be an inexplicable fact if man had not been modified by this
agency, which appears to have acted powerfully on innumerable animals.
It can further be shewn that the differences between the races of man,
as in colour, hairiness, form of features, &c., are of a kind which
might have been expected to come under the influence of sexual
selection. But in order to treat this subject properly, I have found
it necessary to pass the whole animal kingdom in review. I have
therefore devoted to it the Second Part of this work. At the close I
shall return to man, and, after attempting to shew how far he has been
modified through sexual selection, will give a brief summary of the
chapters in this First Part.
NOTE ON THE RESEMBLANCES AND DIFFERENCES IN THE STRUCTURE AND THE
DEVELOPMENT OF THE BRAIN IN MAN AND APES. BY PROFESSOR HUXLEY, F. R.
S.
The controversy respecting the nature and the extent of the
differences in the structure of the brain in man and the apes, which
arose some fifteen years ago, has not yet come to an end, though the
subject matter of the dispute is, at present, totally different from
what it was formerly. It was originally asserted and re-asserted, with
singular pertinacity that the brain of all the apes, even the highest,
differs from that of man, in the absence of such conspicuous
structures as the posterior lobes of the cerebral hemispheres, with
the posterior cornu of the lateral ventricle and the hippocampus
minor, contained in those lobes, which are so obvious in man.
But the truth that the structures in question are as well
developed in apes' as in human brains, or even better; and that it
is characteristic of all the primates (if we exclude the lemurs) to
have these parts well developed, stands at present on as secure a
basis as any proposition in comparative anatomy. Moreover, it is
admitted by every one of the long series of anatomists who, of late
years, have paid special attention to the arrangement of the
complicated sulci 0and gyri which appear upon the surface of the
cerebral hemispheres in man and the higher apes, that they are
disposed after the very same pattern in him, as in them. Every
principal gyrus and sulcus of a chimpanzee's brain is clearly
represented in that of a man, so that the terminology which applies to
the one answers for the other. On this point there is no difference of
opinion. Some years since, Professor Bischoff published a memoir* on
the cerebral convolutions of man and apes; and as the purpose of my
learned colleague was certainly not to diminish the value of the
differences between apes and men in this respect, I am glad to make
a citation from him.
* "Die Grosshirnwindungen des Menschen"; Abhandlungen der K.
Bayerischen Akademie, B. x., 1868.
"That the apes, and especially the orang, chimpanzee and gorilla,
come very close to man in their organisation, much nearer than to
any other animal, is a well known fact, disputed by nobody. Looking at
the matter from the point of view of organisation alone, no one
probably would ever have disputed the view of Linnaeus, that man
should be placed, merely as a peculiar species, at the head of the
mammalia and of those apes. Both shew, in all their organs, so close
an affinity, that the most exact anatomical investigation is needed in
order to demonstrate those differences which really exist. So it is
with the brains. The brains of man, the orang, the chimpanzee, the
gorilla, in spite of all the important differences which they present,
come very close to one another" (loc. cit., p. 101).
There remains, then, no dispute as to the resemblance in fundamental
characters, between the ape's brain and man's: nor any as to the
wonderfully close similarity between the chimpanzee, orang and man, in
even the details of the arrangement of the gyri and sulci of the
cerebral hemispheres. Nor, turning to the differences between the
brains of the highest apes and that of man, is there any serious
question as to the nature and extent of these differences. It is
admitted that the man's cerebral hemispheres are absolutely and
relatively larger than those of the orang and chimpanzee; that his
frontal lobes are less excavated by the upward protrusion of the
roof of the orbits; that his gyri and sulci are, as a rule, less
symmetrically disposed, and present a greater number of secondary
plications. And it is admitted that, as a rule, in man, the
temporo-occipital or "external perpendicular" fissure, which is
usually so strongly marked a feature of the ape's brain is but faintly
marked. But it is also clear, that none of these differences
constitutes a sharp demarcation between the man's and the ape's brain.
In respect to the external perpendicular fissure of Gratiolet, in
the human brain for instance, Professor Turner remarks:*
* Convolutions of the Human Cerebrum Topographically Considered,
1866, p. 12.
"In some brains it appears simply as an indentation of the margin of
the hemisphere, but, in others, it tends for some distance more or
less transversely outwards. I saw it in the right hemisphere of a
female brain pass more than two inches outwards; and on another
specimen, also the right hemisphere, it proceeded for four-tenths of
an inch outwards, and then extended downwards, as far as the lower
margin of the outer surface of the hemisphere. The imperfect
definition of this fissure in the majority of human brains, as
compared with its remarkable distinctness in the brain of most
Quadrumana, is owing to the presence, in the former, of certain
superficial, well marked, secondary convolutions which bridge it
over and connect the parietal with the occipital lobe. The closer
the first of these bridging gyri lies to the longitudinal fissure, the
shorter is the external parieto-occipital fissure" (loc. cit., p. 12).
The obliteration of the external perpendicular fissure of Gratiolet,
therefore, is not a constant character of the human brain. On the
other hand, its full development is not a constant character of the
higher ape's brain. For, in the chimpanzee, the more or less extensive
obliteration of the external perpendicular sulcus by "bridging
convolutions," on one side or the other, has been noted over and
over again by Prof. Rolleston, Mr. Marshall, M. Broca and Professor
Turner. At the conclusion of a special paper on this subject the
latter writes:*
* "Notes more especially on the bridging convolutions in the Brain
of the Chimpanzee," Proceedings of the Royal Society of Edinburgh,
1865-6.
"The three specimens of the brain of a Chimpanzee," just described,
prove that the generalisation which Gratiolet has attempted to draw of
the complete absence of the first connecting convolution and the
concealment of the second, as essentially characteristic features in
the brain of this animal, is by no means universally applicable. In
only one specimen did the brain, in these particulars, follow the
law which Gratiolet has expressed. As regards the presence of the
superior bridging convolution, I am inclined to think that it has
existed in one hemisphere, at least, in a majority of the brains of
this animal which have, up to this time, been figured or described.
The superficial position of the second bridging convolution is
evidently less frequent, and has as yet, I believe, only been seen
in the brain (A) recorded in this communication. The asymmetrical
arrangement in the convolutions of the two hemispheres, which previous
observers have referred to in their descriptions, is also well
illustrated in these specimens" (pp. 8, 9).
Even were the presence of the temporo-occipital, or external
perpendicular, sulcus, a mark of distinction between the higher apes
and man, the value of such a distinctive character would be rendered
very doubtful by the structure of the brain in the platyrhine apes. In
fact, while the temporo-occipital is one of the most constant of sulci
in the catarhine, or Old World, apes, it is never very strongly
developed in the New World apes; it is absent in the smaller
platyrhine; rudimentary in Pithecia;* and more or less obliterated
by bridging convolutions in Ateles.
* FIower, "On the Anatomy of Pithecia Monachus," Proceedings of
the Zoological Society, 1862.
A character which is thus variable within the limits of a single
group can have no great taxonomic value.
It is further established, that the degree of asymmetry of the
convolution of the two sides in the human brain is subject to much
individual variation; and that, in those individuals of the bushman
race who have been examined, the gyri and sulci of the two hemispheres
are considerably less complicated and more symmetrical than in the
European brain, while, in some individuals of the chimpanzee, their
complexity and asymmetry become notable. This is particularly the case
in the brain of a young male chimpanzee figured by M. Broca.
(L'ordre des Primates, p. 165, fig. 11.)
Again, as respects the question of absolute size, it is
established that the difference between the largest and the smallest
healthy human brain is greater than the difference between the
smallest healthy human brain and the largest chimpanzee's or orang's
brain.
Moreover, there is one circumstance in which the orang's and
chimpanzee's brains resemble man's, but in which they differ from
the lower apes, and that is the presence of two corpora candicantia-
the Cynomorpha having but one.
In view of these facts I do not hesitate in this year 1874, to
repeat and insist upon the proposition which I enunciated in 1863:*
* Man's Place in Nature, p. 102.
"So far as cerebral structure goes, therefore, it is clear that
man differs less from the chimpanzee or the orang, than these do
even from the monkeys, and that the difference between the brain of
the chimpanzee and of man is almost insignificant when compared with
that between the chimpanzee brain and that of a lemur."
In the paper to which I have referred, Professor Bischoff does not
deny the second part of this statement, but he first makes the
irrelevant remark that it is not wonderful if the brains of an orang
and a lemur are very different; and secondly, goes on to assert
that, "If we successively compare the brain of a man with that of an
orang; the brain of this with that of a chimpanzee; of this with
that of a gorilla, and so on of a Hylobates, Semnopithecus,
Cynocephalus, Cercopithecus, Macacus, Cebus, Callithrix, Lemur,
Stenops, Hapale, we shall not meet with a greater, or even as great
a break in the degree of development of the convolutions, as we find
between the brain of a man and that of an orang or chimpanzee."
To which I reply, firstly, that whether this assertion be true or
false, it has nothing whatever to do with the proposition enunciated
in Man's Place in Nature, which refers not to the development of the
convolutions alone, but to the structure of the whole brain. If
Professor Bischoff had taken the trouble to refer to p. 96 of the work
he criticises, in fact, he would have found the following passage:
"And it is a remarkable circumstance that though, so far as our
present knowledge extends, there is one true structural break in the
series of forms of simian brains, this hiatus does not lie between man
and the manlike apes, but between the lower and the lowest simians, or
in other words, between the Old and New World apes and monkeys and the
lemurs. Every lemur which has yet been examined, in fact, has its
cerebellum partially visible from above; and its posterior lobe,
with the contained posterior cornu and hippocampus minor, more or less
rudimentary. Every marmoset, American monkey, Old World monkey, baboon
or manlike ape, on the contrary, has its cerebellum entirely hidden,
posteriorly, by the cerebral lobes, and possesses a large posterior
cornu with a well-developed hippocampus minor."
This statement was a strictly accurate account of what was known
when it was made; and it does not appear to me to be more than
apparently weakened by the subsequent discovery of the relatively
small development of the posterior lobes in the siamang and in the
howling monkey. Notwithstanding the exceptional brevity of the
posterior lobes in these two species, no one will pretend that their
brains, in the slightest degree, approach those of the lemurs. And if,
instead of putting Hapale out of its natural place, as Professor
Bischoff most unaccountably does, we write the series of animals he
has chosen to mention as follows: Homo, Pithecus, Troglodytes,
Hylobates, Semnopithecus, Cynocephalus, Cereopithecus, Macacus, Cebus,
Callithrix, Hapale, Lemur, Stenops, I venture to reaffirm that the
great break in this series lies between Hapale and Lemur, and that
this break is considerably greater than that between any other two
terms of that series. Professor Bischoff ignores the fact that long
before he wrote, Gratiolet had suggested the separation of the
lemurs from the other primates on the very ground of the difference in
their cerebral characters; and that Professor Flower had made the
following observations in the course of his description of the brain
of the Javan loris:*
* Transactions of the Zoological Society, vol. v., 1862.
"And it is especially remarkable that, in the development of the
posterior lobes, there is no approximation to the lemurine, short
hemisphered brain, in those monkeys which are commonly supposed to
approach this family in other respects, viz., the lower members of the
platyrhine group."
So far as the structure of the adult brain is concerned, then, the
very considerable additions to our knowledge, which have been made
by the researches of so many investigators, during the past ten years,
fully justify the statement which I made in 1863. But it has been
said, that, admitting the similarity between the adult brains of man
and apes, they are nevertheless, in reality, widely different, because
they exhibit fundamental differences in the mode of their development.
No one would be more ready than I to admit the force of this argument,
if such fundamental differences of development really exist. But I
deny that they do exist. On the contrary, there is a fundamental
agreement in the development of the brain in men and apes.
Gratiolet originated the statement that there is a fundamental
difference in the development of the brains of apes and that of man-
consisting in this; that, in the apes, the sulci which first make
their appearance are situated on the posterior region of the
cerebral hemispheres, while, in the human foetus, the sulci first
become visible on the frontal lobes.*
* "Chez tous les singes, les plis posterieurs se developpent les
premiers; les plis anterieurs se developpent plus tard, aussi la
vertebre occipitale et la parietale sont-elles relativement
tres-grandes chez le foetus. L'Homme presente une exception
remarquable quant a l'epoque de l'apparition des plis frontaux, qui
sont les premiers indiques; mais le developpement general du lobe
frontal, envisage seulement par rapport a son volume, suit les memes
lois que dans les singes"; Gratiolet, Memoire sur les plis cerebres de
l'Homme et des Primateaux, p. 39, tab. iv, fig. 3.
This general statement is based upon two observations, the one of
a gibbon almost ready to be born, in which the posterior gyri were
"well developed," while those of the frontal lobes were "hardly
indicated"* (loc. cit., p. 39), and the other of a human foetus at the
22nd or 23rd week of utero-gestation, in which Gratiolet notes that
the insula was uncovered, but that nevertheless "des incisures
sement de lobe anterieur, une scissure peu profonde indique la
separation du lobe occipital, tres-reduit, d'ailleurs des cette
epoque. Le reste de la surface cerebrale est encore absolument lisse."
* Gratiolet's words are (loc. cit., p. 39): "Dans le foetus dont
il s'agit les plis cerebraux posterieurs sont bien developpes,
tandis que les plis du lobe frontal sont a peine indiques." The
figure, however (pl. iv, fig. 3), shews the fissure of Rolando, and
one of the frontal sulci plainly enough. Nevertheless, M. Alix, in his
"Notice sur les travaux anthropologiques de Gratiolet" (Mem. de la
Societe d'Anthropologie de Paris, 1868, page 32), writes thus:
"Gratiolet a eu entre les mains le cerveau d'un foetus de Gibbon,
singe eminemment superieur, et tellement rapproche de l'orang, que des
naturalistes tres-competents l'ont range parmi les anthropoides. M.
Huxley, par exemple, n'hesite pas sur ce point. Eh bien, c'est sur
le cerveau d'un foetus de Gibbon que Gratiolet a vu les
circonvolutions du lobe temporo-sphenoidal deja developpees
lorsqu'il n'existent pas encore de plis sur le lobe frontal. Il
etait donc bien autorise a dire que, chez l'homme les
circonvolutions apparaissent d' a en w, tandis que chez les singes
elles se developpent d'w en a."
Three views of this brain are given in plate II, figs. 1, 2, 3, of
the work cited, shewing the upper, lateral and inferior views of the
hemispheres, but not the inner view. It is worthy of note that the
figure by no means bears out Gratiolet's description, inasmuch as
the fissure (antero-temporal) on the posterior half of the face of the
hemisphere is more marked than any of those vaguely indicated in the
anterior half. If the figure is correct, it in no way justifies
Gratiolet's conclusion: "Il y a donc entre ces cerveaux [those of a
Callithrix and of a gibbon] et celui du foetus humain une difference
fondamental. Chez celui-ci, longtemps avant que les plis temporaux
apparaissent, les plis frontaux, essayent d'exister."
Since Gratiolet's time, however, the development of the gyri and
sulci of the brain has been made the subject of renewed
investigation by Schmidt, Bischoff, Pansch,* and more particularly
by Ecker,*(2) whose work is not only the latest, but by far the most
complete, memoir on the subject.
* Uber die typische Anordnung der Furchen und Windungen auf den
Grosshirn-Hemispharen des Menschen und der Affen," Archiv fur
Anthropologie, iii., 1868
*(2) "Zur Entwicklungsgeschichte der Furchen und Windungen der
Grosshirn-Hemispharen im Foetus des Menschen." Archiv fur
Anthropologie, iii., 1868.
The final results of their inquiries may be summed up as follows:-
1. In the human foetus, the sylvian fissure is formed in the
course of the third month of utero-gestation. In this, and in the
fourth month, the cerebral hemispheres are smooth and rounded (with
the exception of the sylvian depression), and they project backwards
far beyond the cerebellum.
2. The sulci, properly so called, begin to appear in the interval
between the end of the fourth and the beginning of the sixth month
of foetal life, but Ecker is careful to point out that, not only the
time, but the order, of their appearance is subject to considerable
individual variation. In no case, however, are either the frontal or
the temporal sulci the earliest.
The first which appears, in fact, lies on the inner face of the
hemisphere (whence doubtless Gratiolet, who does not seem to have
examined that face in his foetus, overlooked it), and is either the
internal perpendicular (occipito-parietal), or the calcarine sulcus,
these two being close together and eventually running into one
another. As a rule the occipito-parietal is the earlier of the two.
3. At the latter part of this period, another sulcus, the
"posterio-parietal," or "Fissure of Rolando" is developed, and it is
followed, in the course of the sixth month, by the other principal
sulci of the frontal, parietal, temporal and occipital lobes. There
is, however, no clear evidence that one of these constantly appears
before the other; and it is remarkable that, in the brain at the
period described and figured by Ecker (loc. cit., pp. 212-213 tab. II,
figs. 1, 2, 3, 4), the antero-temporal sulcus (scissure parallele)
so characteristic of the ape's brain, is as well, if not better
developed than the fissure of Rolando, and is much more marked than
the proper frontal sulci.
Taking the facts as they now stand, it appears to me that the
order of the appearance of the sulci and gyri in the foetal human
brain is in perfect harmony with the general doctrine of evolution,
and with the view that man has been evolved from some ape-like form;
though there can be no doubt that that form was, in many respects,
different from any member of the primates now living.
Von Baer taught us, half a century ago, that, in the course of their
development, allied animals put on at first, the characters of the
greater groups to which they belong, and, by degrees, assume those
which restrict them within the limits of their family, genus, and
species; and he proved, at the same time, that no developmental
stage of a higher animal is precisely similar to the adult condition
of any lower animal. It is quite correct to say that a frog passes
through the condition of a fish, inasmuch as at one period of its life
the tadpole has all the characters of a fish, and if it went no
further, would have to be grouped among fishes. But it is equally true
that a tadpole is very different from any known fish.
In like manner, the brain of a human foetus, at the fifth month, may
correctly be said to be, not only the brain of an ape, but that of
an arctopithecine or marmoset-like ape; for its hemispheres, with
their great posterior lobster, and with no sulci but the sylvian and
the calcarine, present the characteristics found only in the group
of the arctopithecine primates. But it is equally true, as Gratiolet
remarks, that, in its widely open sylvian fissure, it differs from the
brain of any actual marmoset. No doubt it would be much more similar
to the brain of an advanced foetus of a marmoset. But we know
nothing whatever of the development of the brain in the marmosets.
In the Platyrhini proper, the only observation with which I am
acquainted is due to Pansch, who found in the brain of a foetal
Cebus apella, in addition to the sylvian fissure and the deep
calcarine fissure, only a very shallow antero-temporal fissure
(scissure parallele of Gratiolet).
Now this fact, taken together with the circumstance that the
antero-temporal sulcus is present in such Platyrhini as the Saimiri,
which present mere traces of sulci on the anterior half of the
exterior of the cerebral hemispheres, or none at all, undoubtedly,
so far as it goes, affords fair evidence in favour of Gratiolet's
hypothesis, that the posterior sulci appear before the anterior, in
the brains of the Platyrhini. But, it by no means follows, that the
rule which may hold good for the Platyrhini extends to the
Catarhini. We have no information whatever respecting the
development of the brain in the Cynomorphia; and, as regards the
Anthropomorpha, nothing but the account of the brain of the gibbon
near birth, already referred to. At the present moment there is not
a shadow of evidence to show that the sulci of a chimpanzee's, or
orang's, brain do not appear in the same order as a man's.
Gratiolet opens his preface with the aphorism: "Il est dangereux
dans les sciences de conclure trop vite." I fear he must have
forgotten this sound maxim by the time he had reached the discussion
of the differences between men and apes, in the body of his work. No
doubt, the excellent author of one of the most remarkable
contributions to the just understanding of the mammalian brain which
has ever been made, would have been the first to admit the
insufficiency of his data had he lived to profit by the advance of
inquiry. The misfortune is that his conclusions have been employed
by persons incompetent to appreciate their foundation, as arguments in
favour of obscurantism.*
* For example, M. l'Abbe Lecomte in his terrible pamphlet, Le
Darwinisme et l'origine de l'homme, 1873.
But it is important to remark that, whether Gratiolet was right or
wrong in his hypothesis respecting the relative order of appearance of
the temporal and frontal sulci, the fact remains; that. before
either temporal or frontal sulci, appear, the foetal brain of man
presents characters which are found only in the lowest group of the
primates (leaving out the lemurs); and that this is exactly what we
should expect to be the case, if man has resulted from the gradual
modification of the same form as that from which the other primates
have sprung.
PART TWO
SEXUAL SELECTION
CHAPTER VIII.
PRINCIPLES OF SEXUAL SELECTION.
WITH animals which have their sexes separated, the males necessarily
differ from the females in their organs of reproduction; and these are
the primary sexual characters. But the sexes often differ in what
Hunter has called secondary sexual characters, which are not
directly connected with the act of reproduction; for instance, the
male possesses certain organs of sense or locomotion, of which the
female is quite destitute, or has them more highly-developed, in order
that he may readily find or reach her; or again the male has special
organs of prehension for holding her securely. These latter organs, of
infinitely diversified kinds, graduate into those which are commonly
ranked as primary, and in some cases can hardly be distinguished
from them; we see instances of this in the complex appendages at the
apex of the abdomen in male insects. Unless indeed we confine the term
"primary" to the reproductive glands, it is scarcely possible to
decide which ought to be called primary and which secondary.
The female often differs from the male in having organs for the
nourishment or protection of her young, such as the mammary glands
of mammals, and the abdominal sacks of the marsupials. In some few
cases also the male possesses similar organs, which are wanting in the
female, such as the receptacles for the ova in certain male fishes,
and those temporarily developed in certain male frogs. The females
of most bees are provided with a special apparatus for collecting
and carrying pollen, and their ovipositor is modified into a sting for
the defense of the larvae and the community. Many similar cases
could be given, but they do not here concern us. There are, however,
other sexual differences quite unconnected with the primary
reproductive organs, and it is with these that we are more
especially concerned such as the greater size, strength, and pugnacity
of the male, his weapons of offence or means of defence against
rivals, his gaudy colouring and various ornaments, his power of
song, and other such characters.
Besides the primary and secondary sexual differences, such as the
foregoing, the males and females of some animals differ in
structures related to different habits of life, and not at all, or
only indirectly, to the reproductive functions. Thus the females of
certain flies (Culicidae and Tabanidae) are blood-suckers, whilst
the males, living on flowers, have mouths destitute of mandibles.* The
males of certain moths and of some crustaceans (e. g. Tanais) have
imperfect, closed mouths, and cannot feed. The complemental males of
certain cirripedes live like epiphytic plants either on the female
or the hermaphrodite form, and are destitute of a mouth and of
prehensile limbs. In these cases it is the male which has been
modified, and has lost certain important organs, which the females
possess. In other cases it is the female which has lost such parts;
for instance, the female glow-worm is destitute of wings, as also
are many female moths, some of which never leave their cocoons. Many
female parasitic crustaceans have lost their natatory legs. In some
weevil-beetles (Curculionidae) there is a great difference between the
male and female in the length of the rostrum or snout;*(2) but the
meaning of this and of many analogous differences, is not at all
understood. Differences of structure between the two sexes in relation
to different habits of life are generally confined to the lower
animals; but with some few birds the beak of the male differs from
that of the female. In the Huia of New Zealand the difference is
wonderfully great, and we hear from Dr. Buller*(3) that the male
uses his strong beak in chiselling the larvae of insects out of
decayed wood, whilst the female probes the softer parts with her far
longer, much curved and pliant beak: and thus they mutually aid each
other. In most cases, differences of structure between the sexes are
more or less directly connected with the propagation of the species:
thus a female, which has to nourish a multitude of ova, requires
more food than the male, and consequently requires special means for
procuring it. A male animal, which lives for a very short time,
might lose its organs for procuring food through disuse, without
detriment; but he would retain his locomotive organs in a perfect
state, so that he might reach the female. The female, on the other
hand, might safely lose her organs for flying, swimming, or walking,
if she gradually acquired habits which rendered such powers useless.
* Westwood, Modern Classification of Insects, vol. ii., 1840, p.
541. For the statement about Tanais, mentioned below, I am indebted to
Fritz Muller.
*(2) Kirby and Spence, Introduction to Entomology, vol. iii.,
1826, p. 309.
*(3) Birds of New Zealand, 1872, p. 66.
We are, however, here concerned only with sexual selection. This
depends on the advantage which certain individuals have over others of
the same sex and species solely in respect of reproduction. When, as
in the cases above mentioned, the two sexes differ in structure in
relation to different habits of life, they have no doubt been modified
through natural selection, and by inheritance, limited to one and
the same sex. So again the primary sexual organs, and those for
nourishing or protecting the young, come under the same influence; for
those individuals which generated or nourished their offspring best,
would leave, ceteris paribus, the greatest number to inherit their
superiority; whilst those which generated or nourished their offspring
badly, would leave but few to inherit their weaker powers. As the male
has to find the female, he requires organs of sense and locomotion,
but if these organs are necessary for the other purposes of life, as
is generally the case, they will have been developed through natural
selection. When the male has found the female, he sometimes absolutely
requires prehensile organs to hold her; thus Dr. Wallace informs me
that the males of certain moths cannot unite with the females if their
tarsi or feet are broken. The males of many oceanic crustaceans,
when adult, have their legs and antennae modified in an
extraordinary manner for the prehension of the female; hence we may
suspect that it is because these animals are washed about by the waves
of the open sea, that they require these organs in order to
propagate their kind, and if so, their development has been the result
of ordinary or natural selection. Some animals extremely low in the
scale have been modified for this same purpose; thus the males of
certain parasitic worms, when fully grown, have the lower surface of
the terminal part of their bodies roughened like a rasp, and with this
they coil round and permanently hold the females.*
* M. Perrier advances this case (Revue Scientifique, Feb. 1, 1873,
p. 865) as one fatal to the belief in sexual election, inasmuch as
he supposes that I attribute all the differences between the sexes
to sexual selection. This distinguished naturalist, therefore, like so
many other Frenchmen, has not taken the trouble to understand even the
first principles of sexual selection. An English naturalist insists
that the claspers of certain male animals could not have been
developed through the choice of the female! Had I not met with this
remark, I should not have thought it possible for any one to have read
this chapter and to have imagined that I maintain that the choice of
the female had anything to do with the development of the prehensile
organs in the male.
When the two sexes follow exactly the same habits of life, and the
male has the sensory or locomotive organs more highly developed than
those of the female, it may be that the perfection of these is
indispensable to the male for finding the female; but in the vast
majority of cases, they serve only to give one male an advantage
over another, for with sufficient time, the less well-endowed males
would succeed in pairing with the females; and judging from the
structure of the female, they would be in all other respects equally
well adapted for their ordinary habits of life. Since in such cases
the males have acquired their present structure, not from being better
fitted to survive in the struggle for existence, but from having
gained an advantage over other males, and from having transmitted this
advantage to their male offspring alone, sexual selection must here
have come into action. It was the importance of this distinction which
led me to designate this form of selection as Sexual Selection. So
again, if the chief service rendered to the male by his prehensile
organs is to prevent the escape of the female before the arrival of
other males, or when assaulted by them, these organs will have been
perfected through sexual selection, that is by the advantage
acquired by certain individuals over their rivals. But in most cases
of this kind it is impossible to distinguish between the effects of
natural and sexual selection. Whole chapters could be filled with
details on the differences between the sexes in their sensory,
locomotive, and prehensile organs. As, however, these structures are
not more interesting than others adapted for the ordinary purposes
of life, I shall pass them over almost entirely, giving only a few
instances under each class.
There are many other structures and instincts which must have been
developed through sexual selection- such as the weapons of offence and
the means of defence- of the males for fighting with and driving
away their rivals- their courage and pugnacity- their various
ornaments- their contrivances for producing vocal or instrumental
music- and their glands for emitting odours, most of these latter
structures serving only to allure or excite the female. It is clear
that these characters are the result of sexual and not of ordinary
selection, since unarmed, unornamented, or unattractive males would
succeed equally well in the battle for life and in leaving a
numerous progeny, but for the presence of better endowed males. We may
infer that this would be the case, because the females, which are
unarmed and unornamented, are able to survive and procreate their
kind. Secondary sexual characters of the kind just referred to, will
be fully discussed in the following chapters, as being in many
respects interesting, but especially as depending on the will, choice,
and rivalry of the individuals of either sex. When we behold two males
fighting for the possession of the female, or several male birds
displaying their gorgeous plumage, and performing strange antics
before an assembled body of females, we cannot doubt that, though
led by instinct, they know what they are about, and consciously
exert their mental and bodily powers.
Just as man can improve the breeds of his game-cocks by the
selection of those birds which are victorious in the cock-pit, so it
appears that the strongest and most vigorous males, or those
provided with the best weapons, have prevailed under nature, and
have led to the improvement of the natural breed or species. A
slight degree of variability leading to some advantage, however
slight, in reiterated deadly contests would suffice for the work of
sexual selection; and it is certain that secondary sexual characters
are eminently variable. Just as man can give beauty, according to
his standard of taste, to his male poultry, or more strictly can
modify the beauty originally acquired by the parent species, can
give to the Sebright bantam a new and elegant plumage, an erect and
peculiar carriage- so it appears that female birds in a state of
nature, have by a long selection of the more attractive males, added
to their beauty or other attractive qualities. No doubt this implies
powers of discrimination and taste on the part of the female which
will at first appear extremely improbable; but by the facts to be
adduced hereafter, I hope to be able to shew that the females actually
have these powers. When, however, it is said that the lower animals
have a sense of beauty, it must not be supposed that such sense is
comparable with that of a cultivated man, with his multiform and
complex associated ideas. A more just comparison would be between
the taste for the beautiful in animals, and that in the lowest
savages, who admire and deck themselves with any brilliant,
glittering, or curious object.
From our ignorance on several points, the precise manner in which
sexual selections acts is somewhat uncertain. Nevertheless if those
naturalists who already believe in the mutability of species, will
read the following chapters, they will, I think, agree with me, that
sexual selection has played an important part in the history of the
organic world. It is certain that amongst almost all animals there
is a struggle between the males for the possession of the female. This
fact is so notorious that it would be superfluous to give instances.
Hence the females have the opportunity of selecting one out of several
males, on the supposition that their mental capacity suffices for
the exertion of a choice. In many cases special circumstances tend
to make the struggle between the males particularly severe. Thus the
males of our migratory birds generally arrive at their places of
breeding before the females, so that many males are ready to contend
for each female. I am informed by Mr. Jenner Weir, that the
bird-catchers assert that this is invariably the case with the
nightingale and blackcap, and with respect to the latter he can
himself confirm the statement.
Mr. Swaysland of Brighton has been in the habit, during the last
forty years, of catching our migratory birds on their first arrival,
and he has never known the females of any species to arrive before
their males. During one spring he shot thirty-nine males of Ray's
wagtail (Budytes raii) before he saw a single female. Mr. Gould has
ascertained by the dissection of those snipes which arrive the first
in this country, that the males come before the females. And the
like holds good with most of the migratory birds of the United
States.* The majority of the male salmon in our rivers, on coming up
from the sea, are ready to breed before the females. So it appears
to be with frogs and toads. Throughout the great class of insects
the males almost always are the first to emerge from the pupal
state, so that they generally abound for a time before any females can
be seen.*(2) The cause of this difference between the males and
females in their periods of arrival and maturity is sufficiently
obvious. Those males which annually first migrated into any country,
or which in the spring were first ready to breed, or were the most
eager, would leave the largest number of offspring; and these would
tend to inherit similar instincts and constitutions. It must be
borne in mind that it would have been impossible to change very
materially the time of sexual maturity in the females, without at
the same time interfering with the period of the production of the
young- a period which must be determined by the seasons of the year.
On the whole there can be no doubt that with almost all animals, in
which the sexes are separate, there is a constantly recurrent struggle
between the males for the possession of the females.
* J. A. Allen, on the "Mammals and Winter Birds of Florida,"
Bulletin of Comparative Zoology, Harvard College, p. 268.
*(2) Even with those plants in which the sexes are separate, the
male flowers are generally mature before the female. As first shewn by
C. K. Sprengel, many hermaphrodite plants are dichogamous; that is,
their male and female organs are not ready at the same time, so that
they cannot be self-fertilised. Now in such flowers, the pollen is
in general matured before the stigma, though there are exceptional
cases in which the female organs are before-hand.
Our difficulty in regard to sexual selection lies in understanding
how it is that the males which conquer other males, or those which
prove the most attractive to the females, leave a greater number of
offspring to inherit their superiority than their beaten and less
attractive rivals. Unless this result does follow, the characters
which give to certain males an advantage over others, could not be
perfected and augmented through sexual selection. When the sexes exist
in exactly equal numbers, the worst-endowed males will (except where
polygamy prevails), ultimately find females, and leave as many
offspring, as well fitted for their general habits of life, as the
best-endowed males. From various facts and considerations, I
formerly inferred that with most animals, in which secondary sexual
characters are well developed, the males considerably exceeded the
females in number; but this is not by any means always true. If the
males were to the females as two to one, or as three to two, or even
in a somewhat lower ratio, the whole affair would be simple; for the
better-armed or more attractive males would leave the largest number
of offspring. But after investigating, as far as possible, the
numerical proportion of the sexes, I do not believe that any great
inequality in number commonly exists. In most cases sexual selection
appears to have been effective in the following manner.
Let us take any species, a bird for instance, and divide the females
inhabiting a district into two equal bodies, the one consisting of the
more vigorous and better-nourished individuals, and the other of the
less vigorous and healthy. The former, there can be little doubt,
would be ready to breed in the spring before the others; and this is
the opinion of Mr. Jenner Weir, who has carefully attended to the
habits of birds during many years. There can also be no doubt that the
most vigorous, best-nourished and earliest breeders would on an
average succeed in rearing the largest number of fine offspring.*
The males, as we have seen, are generally ready to breed before the
females; the strongest, and with some species the best armed of the
males, drive away the weaker; and the former would then unite with the
more vigorous and better-nourished females, because they are the first
to breed.*(2) Such vigorous pairs would surely rear a larger number of
offspring than the retarded females, which would be compelled to unite
with the conquered and less powerful males, supposing the sexes to
be numerically equal; and this is all that is wanted to add, in the
course of successive generations, to the size, strength and courage of
the males, or to improve their weapons.
* Here is excellent evidence on the character of the offspring
from an experienced ornithologist. Mr. J. A. Allen, in speaking
(Mammals and Winter Birds of E. Florida, p. 229) of the later
broods, after the accidental destruction of the first, says, that
these "are found to be smaller and paler-coloured than those hatched
earlier in the season. In cases where several broods are reared each
year, as a general rule the birds of the earlier broods seem in all
respects the most perfect and vigorous."
*(2) Hermann Muller has come to this same conclusion with respect to
those female bees which are the first to emerge from the pupa each
year. See his remarkable essay, "Anwendung der Darwin'schen Lehre
auf Bienen," Verh. d. V. Jahrg., xxix., p. 45
But in very many cases the males which conquer their rivals, do
not obtain possession of the females, independently of the choice of
the latter. The courtship of animals is by no means so simple and
short an affair as might be thought. The females are most excited
by, or prefer pairing with, the more ornamented males, or those
which are the best songsters, or play the best antics; but it is
obviously probable that they would at the same time prefer the more
vigorous and lively males, and this has in some cases been confirmed
by actual observation.* Thus the more vigorous females, which are
the first to breed, will have the choice of many males; and though
they may not always select the strongest or best armed, they will
select those which are vigorous and well armed, and in other
respects the most attractive. Both sexes, therefore, of such early
pairs would as above explained, have an advantage over others in
rearing offspring; and this apparently has sufficed during a long
course of generations to add not only to the strength and fighting
powers of the males, but likewise to their various ornaments or
other attractions.
* With respect to poultry, I have received information, hereafter to
be given, to this effect. Even birds, such as pigeons, which pair
for life, the female, as I hear from Mr. Jenner Weir, will desert
her mate if he is injured or grows weak.
In the converse and much rarer case of the males selecting
particular females, it is plain that those which were the most
vigorous and had conquered others, would have the freest choice; and
it is almost certain that they would select vigorous as well as
attractive females. Such pairs would have an advantage in rearing
offspring, more especially if the male had the power to defend the
female during the pairing-season as occurs with some of the higher
animals, or aided her in providing for the young. The same
principles would apply if each sex preferred and selected certain
individuals of the opposite sex; supposing that they selected not only
the more attractive, but likewise the more vigorous individuals.
Numerical Proportion of the Two Sexes.- I have remarked that
sexual selection would be a simple affair if the males were
considerably more numerous than the females. Hence I was led to
investigate, as far as I could, the proportions between the two
sexes of as many animals as possible; but the materials are scanty.
I will here give only a brief abstract of the results, retaining the
details for a supplementary discussion, so as not to interfere with
the course of my argument. Domesticated animals alone afford the means
of ascertaining the proportional numbers at birth; but no records have
been specially kept for this purpose. By indirect means, however, I
have collected a considerable body of statisties, from which it
appears that with most of our domestic animals the sexes are nearly
equal at birth. Thus 25,560 births of race-horses have been recorded
during twenty-one years, and the male births were to the female births
as 99.7 to 100. In greyhounds the inequality is greater than with
any other animal, for out of 6878 births during twelve years, the male
births were to the female as 110.1 to 100. It is, however, in some
degree doubtful whether it is safe to infer that the proportion
would be the same under natural conditions as under domestication; for
slight and unknown differences in the conditions affect the proportion
of the sexes. Thus with mankind, the male births in England are as
104.5, in Russia as 108.9, and with the Jews of Livonia as 120, to 100
female births. But I shall recur to this curious point of the excess
of male births in the supplement to this chapter. At the Cape of
Good Hope, however, male children of European extraction have been
born during several years in the proportion of between 90 and 99 to
100 female children.
For our present purpose we are concerned with the proportions of the
sexes, not only at birth, but also at maturity, and this adds
another element of doubt; for it is a well-ascertained fact that
with man the number of males dying before or during birth, and
during the first two years of infancy, is considerably larger than
that of females. So it almost certainly is with male lambs, and
probably with some other animals. The males of some species kill one
another by fighting; or they drive one another about until they become
greatly emaciated. They must also be often exposed to various dangers,
whilst wandering about in eager search for the females. In many
kinds of fish the males are much smaller than the females, and they
are believed often to be devoured by the latter, or by other fishes.
The females of some birds appear to die earlier than the males; they
are also liable to be destroyed on their nests, or whilst in charge of
their young. With insects the female larvae are often larger than
those of the males, and would consequently be more likely to be
devoured. In some cases the mature females are less active and less
rapid in their movements than the males, and could not escape so
well from danger. Hence, with animals in a state of nature, we must
rely on mere estimation, in order to judge of the proportions of the
sexes at maturity; and this is but little trustworthy, except when the
inequality is strongly marked. Nevertheless, as far as a judgment
can be formed, we may conclude from the facts given in the supplement,
that the males of some few mammals, of many birds, of some fish and
insects, are considerably more numerous than the females.
The proportion between the sexes fluctuates slightly during
successive years: thus with race-horses, for every 100 mares born
the stallions varied from 107.1 in one year to 92.6 in another year,
and with greyhounds from 116.3 to 95.3. But had larger numbers been
tabulated throughout an area more extensive than England, these
fluctuations would probably have disappeared; and such as they are,
would hardly suffice to lead to effective sexual selection in a
state of nature. Nevertheless, in the cases of some few wild
animals, as shewn in the supplement, the proportions seem to fluctuate
either during different seasons or in different localities in a
sufficient degree to lead to such selection. For it should be observed
that any advantage, gained during certain years or in certain
localities by those males which were able to conquer their rivals,
or were the most attractive to the females, would probably be
transmitted to the offspring, and would not subsequently be
eliminated. During the succeeding seasons, when, from the equality
of the sexes, every male was able to procure a female, the stronger or
more attractive males previously produced would still have at least as
good a chance of leaving offspring as the weaker or less attractive.
Polygamy.- The practice of polygamy leads to the same results as
would follow from an actual inequality in the number of the sexes; for
if each male secures two or more females, many males cannot pair;
and the latter assuredly will be the weaker or less attractive
individuals. Many mammals and some few birds are polygamous, but
with animals belonging to the lower classes I have found no evidence
of this habit. The intellectual powers of such animals are, perhaps,
not sufficient to lead them to collect and guard a harem of females.
That some relation exists between polygamy and the development of
secondary sexual characters, appears nearly certain; and this supports
the view that a numerical preponderance of males would be eminently
favourable to the action of sexual selection. Nevertheless many
animals, which are strictly monogamous, especially birds, display
strongly-marked secondary sexual characters; whilst some few
animals, which are polygamous, do not have such characters.
We will first briefly run through the mammals, and then turn to
birds. The gorilla seems to be polygamous, and the male differs
considerably from the female; so it is with some baboons, which live
in herds containing twice as many adult females as males. In South
America the Mycetes caraya present well-marked sexual differences,
in colour, beard, and vocal organs; and the male generally lives
with two or three wives: the male of the Cebus capucinus differs
somewhat from the female, and appears to be polygamous.* Little is
known on this head with respect to most other monkeys, but some
species are strictly monogamous. The ruminants are eminently
polygamous, and they present sexual differences more frequently than
almost any other group of mammals; this holds good, especially in
their weapons, but also in other characters. Most deer, cattle, and
sheep are polygamous; as are most antelopes, though some are
monogamous. Sir Andrew Smith, in speaking of the antelopes of South
Africa, says that in herds of about a dozen there was rarely more than
one mature male. The Asiatic Antilope saiga appears to be the most
inordinate polygamist in the world; for Pallas*(2) states that the
male drives away all rivals, and collects a herd of about a hundred
females and kids together; the female is hornless and has softer hair,
but does not otherwise differ much from the male. The wild horse of
the Falkland Islands and of the western states of N. America is
polygamous, but, except in his greater size and in the proportions
of his body, differs but little from the mare. The wild boar
presents well-marked sexual characters, in his great tusks and some
other points. In Europe and in India he leads a solitary life,
except during the breeding-season; but as is believed by Sir W.
Elliot, who has had many opportunities in India of observing this
animal, he consorts at this season with several females. Whether
this holds good in Europe is doubtful, but it is supported by some
evidence. The adult male Indian elephant, like the boar, passes much
of his time in solitude; but as Dr. Campbell states, when with others,
"It is rare to find more than one male with a whole herd of
females"; the larger males expelling or killing the smaller and weaker
ones. The male differs from the female in his immense tusks, greater
size, strength, and endurance; so great is the difference in these
respects that the males when caught are valued at one-fifth more
than the females.*(3) The sexes of other pachydermatous animals differ
very little or not at all, and, as far as known, they are not
polygamists. Nor have I heard of any species in the Orders of
Cheiroptera, Edentata, Insectivora and rodents being polygamous,
excepting that amongst the rodents, the common rat, according to
some rat-catchers, lives with several females. Nevertheless the two
sexes of some sloths (Edentata) differ in the character and colour
of certain patches of hair on their shoulders.*(4) And many kinds of
bats (Cheiroptera) present well-marked sexual differences, chiefly
in the males possessing odoriferous glands and pouches, and by their
being of a lighter colour.*(5) In the great order of rodents, as far
as I can learn, the sexes rarely differ, and when they do so, it is
but slightly in the tint of the fur.
* On the Gorilla, Savage and Wyman, Boston Journal of Natural
History, vol. v., 1845-47, p. 423. On Cynocephalus, Brehm,
Illustriertes Thierleben, B. i., 1864, s. 77. On Mycetes, Rengger,
Naturgeschichte der Saugethiere von Paraguay, 1830, ss. 14, 20. On
Cebus, Brehm, ibid., s. 108.
*(2) Pallas, Spicilegia Zoolog., fasc. xii., 1777, p. 29. Sir Andrew
Smith, Illustrations of the Zoology of S. Africa, 1849, pl. 29, on the
Kobus. Owen, in his Anatomy of Vertebrates (vol. iii., 1868, p. 633)
gives a table shewing incidentally which species of antelopes are
gregarious.
*(3) Dr. Campbell, in Proc., Zoolog. Soc., 1869, p. 138. See also an
interesting paper by Lieut. Johnstone, in Proceedings, Asiatic Society
of Bengal, May, 1868.
*(4) Dr. Gray, in Annals and Magazine of Natural History, 1871, p.
302.
*(5) See Dr. Dobson's excellent paper in Proceedings of the
Zoological Society, 1873, p. 241.
As I hear from Sir Andrew Smith, the lion in South Africa
sometimes lives with a single female, but generally with more, and, in
one case, was found with as many as five females; so that he is
polygamous. As far as I can discover, he is the only polygamist
amongst all the terrestrial Carnivora, and he alone presents
well-marked sexual characters. If, however, we turn to the marine
Carnivora, as we shall hereafter see, the case is widely different;
for many species of seals offer extraordinary sexual differences,
and they are eminently polygamous. Thus, according to Peron, the
male sea-elephant of the southern ocean always possesses several
females, and the sea-lion of Forster is said to be surrounded by
from twenty to thirty females. In the North, the male sea-bear of
Steller is accompanied by even a greater number of females. It is an
interesting fact, as Dr. Gill remarks,* that in the monogamous
species, "or those living in small communities, there is little
difference in size between the males and females; in the social
species, or rather those of which the males have harems, the males are
vastly larger than the females."
* "The Eared Seals," American Naturalist, vol. iv., Jan. 1871.
Amongst birds, many species, the sexes of which differ greatly
from each other, are certainly monogamous. In Great Britain we see
well-marked sexual differences, for instance, in the wild-duck which
pairs with a single female, the common blackbird, and the bullfinch
which is said to pair for life. I am informed by Mr. Wallace that
the like is true of chatterers or Cotingidae of South America, and
of many other birds. In several groups I have not been able to
discover whether the species are polygamous or monogamous. Lesson says
that birds of paradise, so remarkable for their sexual differences,
are polygamous, but Mr. Wallace doubts whether he had sufficient
evidence. Mr. Salvin tells me he has been led to believe that
humming-birds are polygamous. The male widow-bird, remarkable for
his caudal plumes, certainly seems to be a polygamist.* I have been
assured by Mr. Jenner Weir and by others, that it is somewhat common
for three starlings to frequent the same nest; but whether this is a
case of polygamy or polyandry has not been ascertained.
* The Ibis, vol. iii., 1861, p. 133, on the Progne widow-bird. See
also on the Vidua axillaris, ibid., vol. ii., 1860, p. 211. On the
polygamy of the capercailzie and great bustard, see L. Lloyd, Game
Birds of Sweden, 1867, pp. 19, and 182. Montagu and Selby speak of the
black grouse as polygamous and of the red grouse as monogamous.
The Gallinaceae exhibit almost as strongly marked sexual differences
as birds of paradise or humming-birds, and many of the species are, as
is well know, polygamous; others being strictly monogamous. What a
contrast is presented between the sexes of the polygamous peacock or
pheasant, and the monogamous guinea-fowl or partridge! Many similar
cases could be given, as in the grouse tribe, in which the males of
the polygamous capercailzie and black-cock differ greatly from the
females; whilst the sexes of the monogamous red grouse and ptarmigan
differ very little. In the Cursores, except amongst the bustards,
few species offer strongly-marked sexual differences, and the great
bustard (Otis tarda) is said to be polygamous. With the Grallatores,
extremely few species differ sexually, but the ruff (Machetes
pugnax) affords a marked exception, and this species is believed by
Montagu to be a polygamist. Hence it appears that amongst birds
there often exists a close relation between polygamy and the
development of strongly-marked sexual differences. I asked Mr.
Bartlett, of the Zoological Gardens, who has had very large experience
with birds, whether the male tragopan (one of the Gallinaceae) was
polygamous, and I was struck by his answering, "I do not know, but
should think so from his splendid colours."
It deserves notice that the instinct of pairing with a single female
is easily lost under domestication. The wild-duck is strictly
monogamous, the domestic-duck highly polygamous. The Rev. W. D. Fox
informs me that out of some half-tamed wild-ducks, on a large pond
in his neighborhood, so many mallards were shot by the game-keeper
that only one was left for every seven or eight females; yet unusually
large broods were reared. The guinea-fowl is strictly monogamous;
but Mr. Fox finds that his birds succeed best when he keeps one cock
to two or three hens. Canary-birds pair in a state of nature, but
the breeders in England successfully put one male to four or five
females. I have noticed these cases, as rendering it probable that
wild monogamous species might readily become either temporarily or
permanently polygamous.
Too little is known of the habits of reptiles and fishes to enable
us to speak of their marriage arrangements. The stickle-back
(Gasterosteus), however, is said to be a polygamist;* and the male
during the breeding-season differs conspicuously from the female.
* Noel Humphreys, River Gardens, 1857.
To sum up on the means through which, as far as we can judge, sexual
selection has led to the development of secondary sexual characters.
It has been shewn that the largest number of vigorous offspring will
be reared from the pairing of the strongest and best-armed males,
victorious in contests over other males, with the most vigorous and
best-nourished females, which are the first to breed in the spring. If
such females select the more attractive, and at the same time vigorous
males, they will rear a larger number of offspring than the retarded
females, which must pair with the less vigorous and less attractive
males. So it will be if the more vigorous males select the more
attractive and at the same time healthy and vigorous females; and this
will especially hold good if the male defends the female, and aids
in providing food for the young. The advantage thus gained by the more
vigorous pairs in rearing a larger number of offspring has
apparently sufficed to render sexual selection efficient. But a
large numerical preponderance of males over females will be still more
efficient; whether the preponderance is only occasional and local,
or permanent; whether it occurs at birth, or afterwards from the
greater destruction of the females; or whether it indirectly follows
from the practice of polygamy.
The Male generally more modified than the Female.- Throughout the
animal kingdom, when the sexes differ in external appearance, it is,
with rare exceptions, the male which has been the more modified;
for, generally, the female retains a closer resemblance to the young
of her own species, and to other adult members of the same group.
The cause of this seems to lie in the males of almost all animals
having stronger passions than the females. Hence it is the males
that fight together and sedulously display their charms before the
females; and the victors transmit their superiority to their male
offspring. Why both sexes do not thus acquire the characters of
their fathers, will be considered hereafter. That the males of all
mammals eagerly pursue the females is notorious to every one. So it is
with birds; but many cock birds do not so much pursue the hen, as
display their plumage, perform strange antics, and pour forth their
song in her presence. The male in the few fish observed seems much
more eager than the female; and the same is true of alligators, and
apparently of batrachians. Throughout the enormous class of insects,
as Kirby remarks, "the law is that the male shall seek the female."*
Two good authorities, Mr. Blackwell and Mr. C. Spence Bate, tell me
that the males of spiders and crustaceans are more active and more
erratic in their habits than the females. When the organs of sense
or locomotion are present in the one sex of insects and crustaceans
and absent in the other, or when, as is frequently the case, they
are more highly developed in the one than in the other, it is, as
far as I can discover, almost invariably the male which retains such
organs, or has them most developed; and this shews that the male is
the more active member in the courtship of the sexes.*(2)
* Kirby and Spence, Introduction to Entomology, vol. iii., 1826,
p. 342.
*(2) One parasitic hymenopterous insect (Westwood, Modern Class.
of Insects, vol. ii., p. 160) forms an exception to the rule, as the
male has rudimentary wings, and never quits the cell in which it is
born, whilst the female has well-developed wings. Audouin believes
that the females of this species are impregnated by the males which
are born in the same cells with them; but it is much more probable
that the females visit other cells, so that close inter-breeding is
thus avoided. We shall hereafter meet in various classes, with a few
exceptional cases, in which the female, instead of the male, is the
seeker and wooer.
The female, on the other hand, with the rarest exceptions, is less
eager than the male. As the illustrious Hunter* long ago observed, she
generally "requires to be courted"; she is coy, and may often be
seen endeavouring for a long time to escape from the male. Every
observer of the habits of animals will be able to call to mind
instances of this kind. It is shown by various facts, given hereafter,
and by the results fairly attributable to sexual selection, that the
female, though comparatively passive, generally exerts some choice and
accepts one male in preference to others. Or she may accept, as
appearances would sometimes lead us to believe, not the male which
is the most attractive to her, but the one which is the least
distasteful. The exertion of some choice on the part of the female
seems a law almost as general as the eagerness of the male.
* Essays and Observations, edited by Owen, vol. i., 1861, p. 194.
We are naturally led to enquire why the male, in so many and such
distinct classes, has become more eager than the female, so that he
searches for her, and plays the more active part in courtship. It
would be no advantage and some loss of power if each sex searched
for the other; but why should the male almost always be the seeker?
The ovules of plants after fertilisation have to be nourished for a
time; hence the pollen is necessarily brought to the female organs-
being placed on the stigma, by means of insects or the wind, or by the
spontaneous movements of the stamens; and in the Algae, &c., by the
locomotive power of the antherozooids. With lowly-organised aquatic
animals, permanently affixed to the same spot and having their sexes
separate, the male element is invariably brought to the female; and of
this we can see the reason, for even if the ova were detached before
fertilisation, and did not require subsequent nourishment or
protection, there would yet be greater difficulty in transporting them
than the male element, because, being larger than the latter, they are
produced in far smaller numbers. So that many of the lower animals
are, in this respect, analogous with plants.* The males of affixed and
aquatic animals having been led to emit their fertilising element in
this way, it is natural that any of their descendants, which rose in
the scale and became locomotive, should retain the same habit; and
they would approach the female as closely as possible, in order not to
risk the loss of the fertilising element in a long passage of it
through the water. With some few of the lower animals, the females
alone are fixed, and the males of these must be the seekers. But it is
difficult to understand why the males of species, of which the
progenitors were primordially free, should invariably have acquired
the habit of approaching the females, instead of being approached by
them. But in all cases, in order that the males should seek
efficiently, it would be necessary that they should be endowed with
strong passions; and the acquirement of such passions would
naturally follow from the more eager leaving a larger number of
offspring than the less eager.
* Prof. Sachs (Lehrbuch der Botanik, 1870, S. 633) in speaking of
the male and female reproductive cells, remarks, "verhalt sich die
eine bei der Vereinigung activ,... die andere erscheint bei der
Vereinigung passiv."
The great eagerness of the males has thus indirectly led to their
much more frequently developing secondary sexual characters than the
females. But the development of such characters would be much aided,
if the males were more liable to vary than the females- as I concluded
they were- after a long study of domesticated animals. Von
Nathusius, who has had very wide experience, is strongly of the same
opinion.* Good evidence also in favour of this conclusion can be
produced by a comparison of the two sexes in mankind. During the
Novara expedition*(2) a vast number of measurements was made of
various parts of the body in different races, and the men were found
in almost every case to present a greater range of variation than
the women; but I shall have to recur to this subject in a future
chapter. Mr. J. Wood,*(3) who has carefully attended to the
variation of the muscles in man, puts in italics the conclusion that
"the greatest number of abnormalities in each subject is found in
the males." He had previously remarked that "altogether in 102
subjects, the varieties of redundancy were found to be half as many
again as in females, contrasting widely with the greater frequency
of deficiency in females before described." Professor Macalister
likewise remarks*(4) that variations in the muscles "are probably more
common in males than females." Certain muscles which are not
normally present in mankind are also more frequently developed in
the male than in the female sex, although exceptions to this rule
are said to occur. Dr. Burt Wilder*(5) has tabulated the cases of
152 individuals with supernumerary digits, of which 86 were males, and
39, or less than half, females, the remaining 27 being of unknown sex.
It should not, however, be overlooked that women would more frequently
endeavour to conceal a deformity of this kind than men. Again, Dr.
L. Meyer asserts that the ears of man are more variable in form than
those of a woman.*(6) Lastly the temperature is more variable in man
than in woman.*(7)
* Vortrage uber Viehzucht, 1872, p. 63.
*(2) Reise der Novara: Anthropolog. Theil, 1867, ss. 216-269. The
results were calculated by Dr. Weisbach from measurements made by Drs.
K. Scherzer and Schwarz. On the greater variability of the males of
domesticated animals, see my Variation of Animals and Plants under
Domestication, vol. ii., 1868, p. 75.
*(3) Proceedings of the Royal Society, vol. xvi., July, 1868, pp.
519 and 524.
*(4) Proc. Royal Irish Academy, vol. x., 1868, p. 123.
*(5) Mass. Medical Society, ii., No. 3, 1868, p. 9.
*(6) Archiv fur Path. Anat. und Phys., 1871, p. 488.
*(7) The conclusions recently arrived at by Dr. J. Stockton Hough,
on the temperature of man, are given in the Pop. Sci. Review, Jan.
1, 1874, p. 97.
The cause of the greater general variability in the male sex, than in
the female is unknown, except in so far as secondary sexual characters
are extraordinarily variable, and are usually confined to the males;
and, as we shall presently see, this fact is, to a certain extent,
intelligible. Through the action of sexual and natural selection
male animals have been rendered in very many instances widely
different from their females; but independently of selection the two
sexes, from differing constitutionally, tend to vary in a somewhat
different manner. The female has to expend much organic matter in
the formation of her ova, whereas the male expends much force in
fierce contests with his rivals, in wandering about in search of the
female, in exerting his voice, pouring out odoriferous secretions,
&c.: and this expenditure is generally concentrated within a short
period. The great vigour of the male during the season of love seems
often to intensify his colours, independently of any marked difference
from the female.* In mankind, and even as low down in the organic
scale as in the Lepidoptera, the temperature of the body is higher
in the male than in the female, accompanied in the case of man by a
slower pulse.*(2) On the whole the expenditure of matter and force
by the two sexes is probably nearly equal, though effected in very
different ways and at different rates.
* Prof. Mantegazza is inclined to believe ("Lettera a Carlo Darwin,"
Archivio per l'Anthropologia, 1871, p. 306) that the bright colours,
common in so many male animals, are due to the presence and
retention by them of the spermatic fluid; but this can hardly be the
case; for many male birds, for instance young pheasants, become
brightly coloured in the autumn of their first year.
*(2) For mankind, see Dr. J. Stockton Hough, whose conclusions are
given in the Popular Science Review, 1874, p. 97. See Girard's
observations on the Lepidoptera, as given in the Zoological Record,
1869, p. 347.
From the causes just specified the two sexes can hardly fail to
differ somewhat in constitution, at least during the
breeding-season; and, although they may be subjected to exactly the
same conditions, they will tend to vary in a different manner. If such
variations are of no service to either sex, they will not be
accumulated and increased by sexual or natural selection.
Nevertheless, they may become permanent if the exciting cause acts
permanently; and in accordance with a frequent form of inheritance
they may be transmitted to that sex alone in which they first
appeared. In this case the two sexes will come to present permanent,
yet unimportant, differences of character. For instance, Mr. Allen
shews that with a large number of birds inhabiting the northern and
southern United States, the specimens from the south are
darker-coloured than those from the north; and this seems to be the
direct result of the difference in temperature, light, &c., between
the two regions. Now, in some few cases, the two sexes of the same
species appear to have been differently affected; in the Agelaeus
phoeniceus the males have had their colours greatly intensified in the
south; whereas with Cardinalis virginianus it is the females which
have been thus affected; with Quiscalus major the females have been
rendered extremely variable in tint, whilst the males remain nearly
uniform.*
* Mammals and Birds of E. Florida, pp. 234, 280, 295.
A few exceptional cases occur in various classes of animals, in
which the females instead of the males have acquired well pronounced
secondary sexual characters, such as brighter colours, greater size,
strength, or pugnacity. With birds there has sometimes been a complete
transposition of the ordinary characters proper to each sex; the
females having become the more eager in courtship, the males remaining
comparatively passive, but apparently selecting the more attractive
females, as we may infer from the results. Certain hen birds have thus
been rendered more brightly coloured or otherwise ornamented, as
well as more powerful and pugnacious than the cocks; these
characters being transmitted to the female offspring alone.
It may be suggested that in some cases a double process of selection
has been carried on; that the males have selected the more
attractive females, and the latter the more attractive males. This
process, however, though it might lead to the modification of both
sexes, would not make the one sex different from the other, unless
indeed their tastes for the beautiful differed; but this is a
supposition too improbable to be worth considering in the case of
any animal, excepting man. There are, however, many animals in which
the sexes resemble each other, both being furnished with the same
ornaments, which analogy would lead us to attribute to the agency of
sexual selection. In such cases it may be suggested with more
plausibility, that there has been a double or mutual process of sexual
selection; the more vigorous and precocious females selecting the more
attractive and vigorous males, the latter rejecting all except the
more attractive females. But from what we know of the habits of
animals, this view is hardly probable, for the male is generally eager
to pair with any female. It is more probable that the ornaments common
to both sexes were acquired by one sex, generally the male, and then
transmitted to the offspring of both sexes. If, indeed, during a
lengthened period the males of any species were greatly to exceed
the females in number, and then during another lengthened period,
but under different conditions, the reverse were to occur, a double,
but not simultaneous, process of sexual selection might easily be
carried on, by which the two sexes might be rendered widely different.
We shall hereafter see that many animals exist, of which neither sex
is brilliantly coloured or provided with special ornaments, and yet
the members of both sexes or of one alone have probably acquired
simple colours, such as white or black, through sexual selection.
The absence of bright tints or other ornaments may be the result of
variations of the right kind never having occurred, or of the
animals themselves having preferred plain black or white. Obscure
tints have often been developed through natural selection for the sake
of protection, and the acquirement through sexual selection of
conspicuous colours, appears to have been sometimes checked from the
danger thus incurred. But in other cases the males during long ages
may have struggled together for the possession of the females, and yet
no effect will have been produced, unless a larger number of offspring
were left by the more successful males to inherit their superiority,
than by the less successful: and this, as previously shewn, depends on
many complex contingencies.
Sexual selection acts in a less rigorous manner than natural
selection. The latter produces its effects by the life or death at all
ages of the more or less successful individuals. Death, indeed, not
rarely ensues from the conflicts of rival males. But generally the
less successful male merely fails to obtain a female, or obtains a
retarded and less vigorous female later in the season, or, if
polygamous, obtains fewer females; so that they leave fewer, less
vigorous, or no offspring. In regard to structures acquired through
ordinary or natural selection, there is in most cases, as long as
the conditions of life remain the same, a limit to the amount of
advantageous modification in relation to certain special purposes; but
in regard to structures adapted to make one male victorious over
another, either in fighting or in charming the female, there is no
definite limit to the amount of advantageous modification; so that
as long as the proper variations arise the work of sexual selection
will go on. This circumstance may partly account for the frequent
and extraordinary amount of variability presented by secondary
sexual characters. Nevertheless, natural selection will determine that
such characters shall not be acquired by the victorious males, if they
would be highly injurious, either by expending too much of their vital
powers, or by exposing them to any great danger. The development,
however, of certain structures- of the horns, for instance, in certain
stags- has been carried to a wonderful extreme; and in some cases to
an extreme which, as far as the general conditions of life are
concerned, must be slightly injurious to the male. From this fact we
learn that the advantages which favoured males derive from
conquering other males in battle or courtship, and thus leaving a
numerous progeny, are in the long run greater than those derived
from rather more perfect adaptation to their conditions of life. We
shall further see, and it could never have been anticipated, that
the power to charm the female has sometimes been more important than
the power to conquer other males in battle.
LAWS OF INHERITANCE.
In order to understand how sexual selection has acted on many
animals of many classes, and in the course of ages has produced a
conspicuous result, it is necessary to bear in mind the laws of
inheritance, as far as they are known. Two distinct elements are
included under the term "inheritance"- the transmission, and the
development of characters; but as these generally go together, the
distinction is often overlooked. We see this distinction in those
characters which are transmitted through the early years of life,
but are developed only at maturity or during old age. We see the
same distinction more clearly with secondary sexual characters, for
these are transmitted through both sexes, though developed in one
alone. That they are present in both sexes, is manifest when two
species, having strongly-marked sexual characters, are crossed, for
each transmits the characters proper to its own male and female sex to
the hybrid offspring of either sex. The same fact is likewise
manifest, when characters proper to the male are occasionally
developed in the female when she grows old or becomes diseased, as,
for instance, when the common hen assumes the flowing tail-feathers,
hackles, comb, spurs, voice, and even pugnacity of the cock.
Conversely, the same thing is evident, more or less plainly, with
castrated males. Again, independently of old age or disease,
characters are occasionally transferred from the male to the female,
as when, in certain breeds of the fowl, spurs regularly appear in
the young and healthy females. But in truth they are simply
developed in the female; for in every breed each detail in the
structure of the spur is transmitted through the female to her male
offspring. Many cases will hereafter be given, where the female
exhibits, more or less perfectly, characters proper to the male, in
whom they must have been first developed, and then transferred to
the female. The converse case of the first development of characters
in the female and of transference to the male, is less frequent; it
will therefore be well to give one striking instance. With bees the
pollen-collecting apparatus is used by the female alone for
gathering pollen for the larvae, yet in most of the species it is
partially developed in the males to whom it is quite useless, and it
is perfectly developed in the males of Bombus or the humble-bee.* As
not a single other hymenopterous insect, not even the wasp, which is
closely allied to the bee, is provided with a pollen-collecting
apparatus, we have no grounds for supposing that male bees
primordially collected pollen as well as the females; although we have
some reason to suspect that male mammals primordially suckled their
young as well as the females. Lastly, in all cases of reversion,
characters are transmitted through two, three, or many more
generations, and are then developed under certain unknown favourable
conditions. This important distinction between transmission and
development will be best kept in mind by the aid of the hypothesis
of pangenesis. According to this hypothesis, every unit or cell of the
body throws off gemmules or undeveloped atoms, which are transmitted
to the offspring of both sexes, and are multiplied by self-division.
They may remain undeveloped during the early years of life or during
successive generations; and their development into units or cells,
like those from which they were derived, depends on their affinity
for, and union with other units or cells previously developed in the
due order of growth.
* H. Muller, "Anwendung der Darwin'schen Lehre, &c.," Verh. d. n. V.
Jahrg., xxix. p. 42.
Inheritance at corresponding Periods of Life.- This tendency is well
established. A new character, appearing in a young animal, whether
it lasts throughout life or is only transient, will, in general,
reappear in the offspring at the same age and last for the same
time. If, on the other hand, a new character appears at maturity, or
even during old age, it tends to reappear in the offspring at the same
advanced age. When deviations from this rule occur, the transmitted
characters much oftener appear before, than after the corresponding
age. As I have dwelt on this subject sufficiently in another work,*
I will here merely give two or three instances, for the sake of
recalling the subject to the reader's mind. In several breeds of the
fowl, the down-covered chickens, the young birds in their first true
plumage, and the adults differ greatly from one another, as well as
from their common parent-form, the Gallus bankiva; and these
characters are faithfully transmitted by each breed to their offspring
at the corresponding periods of life. For instance, the chickens of
spangled Hamburgs, whilst covered with down have a few dark spots on
the head and rump, but are not striped longitudinally, as in many
other breeds; in their first true plumage, "they are beautifully
pencilled," that is each feather is transversely marked by numerous
dark bars; but in their second plumage the feathers all become
spangled or tipped with a dark round spot.*(2) Hence in this breed
variations have occurred at, and been transmitted to, three
distinct periods of life. The pigeon offers a more remarkable case,
because the aboriginal parent species does not undergo any change of
plumage with advancing age, excepting that at maturity the breast
becomes more iridescent; yet there are breeds which do not acquire
their characteristic colours until they have moulted two, three, or
four times; and these modifications of plumage are regularly
transmitted.
* The Variation of Animals and Plants under Domestication, vol. ii.,
1868, p. 75. In the last chapter but one, the provisional hypothesis
of pangenesis, above alluded to, is fully explained.
*(2) These facts are given on the high authority of a great breeder,
Mr. Teebay; see Tegetmeier's Poultry Book, 1868, p. 158. On the
characters of chickens of different breeds, and on the breeds of the
pigeon, alluded to in the following paragraph, see Variation of
Animals, &c., vol. i., pp. 160, 249; vol. ii., p. 77.
Inheritance at corresponding Seasons of the Year.- With animals in a
state of nature, innumerable instances occur of characters appearing
periodically at different seasons. We see this in the horns of the
stag, and in the fur of arctic animals which becomes thick and white
during the winter. Many birds acquire bright colours and other
decorations during the breeding-season alone. Pallas states,* that
in Siberia domestic cattle and horses become lighter-coloured during
the winter; and I have myself observed, and heard of similar
strongly marked changes of colour, that is, from brownish cream-colour
or reddish-brown to a perfect white, in several ponies in England.
Although I do not know that this tendency to change the colour of
the coat during different seasons is transmitted, yet it probably is
so, as all shades of colour are strongly inherited by the horse. Nor
is this form of inheritance, as limited by the seasons, more
remarkable than its limitation by age or sex.
* Novae species Quadrupedum e Glirium ordine, 1778, p. 7. On the
transmission of colour by the horse, see Variation of Animals and
Plants under Domestication, vol. i., p. 51. Also vol. ii., p. 71,
for a general discussion on "Inheritance as limited by Sex."
Inheritance as Limited by Sex.- The equal transmission of characters
to both sexes is the commonest form of inheritance, at least with
those animals which do not present strongly-marked sexual differences,
and indeed with many of these. But characters are somewhat commonly
transferred exclusively to that sex, in which they first appear. Ample
evidence on this head has been advanced in my work on Variation
under Domestication, but a few instances may here be given. There
are breeds of the sheep and goat, in which the horns of the male
differ greatly in shape from those of the female; and these
differences, acquired under domestication, are regularly transmitted
to the same sex. As a rule, it is the females alone in cats which
are tortoise-shell, the corresponding colour in the males being
rusty-red. With most breeds of the fowl, the characters proper to each
sex are transmitted to the same sex alone. So general is this form
of transmission that it is an anomaly when variations in certain
breeds are transmitted equally to both sexes. There are also certain
sub-breeds of the fowl in which the males can hardly be
distinguished from one another, whilst the females differ considerably
in colour. The sexes of the pigeon in the parent-species do not differ
in any external character; nevertheless, in certain domesticated
breeds the male is coloured differently from the female.* The wattle
in the English carrier pigeon, and the crop in the pouter, are more
highly developed in the male than in the female; and although these
characters have been gained through long-continued selection by man,
the slight differences between the sexes are wholly due to the form of
inheritance which has prevailed; for they have arisen, not from, but
rather in opposition to, the wish of the breeder.
* Dr. Chapuis, Le Pigeon Voyageur Belge, 1865, p. 87. Boitard et
Corbie, Les Pigeons de Voliere, &c., 1824, p. 173. See, also, on
similar differences in certain breeds at Modena, Le variazioni dei
Colombi domestici, del Paolo Bonizzi, 1873.
Most of our domestic races have been formed by the accumulation of
many slight variations; and as some of the successive steps have
been transmitted to one sex alone, and some to both sexes, we find
in the different breeds of the same species all gradations between
great sexual dissimilarity and complete similarity. Instances have
already been given with the breeds of the fowl and pigeon, and under
nature analogous cases are common. With animals under domestication,
but whether in nature I will not venture to say, one sex may lose
characters proper to it, and may thus come somewhat to resemble the
opposite sex; for instance, the males of some breeds of the fowl
have lost their masculine tail-plumes and hackles. On the other
hand, the differences between the sexes may be increased under
domestication, as with merino sheep, in which the ewes have lost their
horns. Again, characters proper to one sex may suddenly appear in
the other sex; as in those sub-breeds of the fowl in which the hens
acquire spurs whilst young; or, as in certain Polish sub-breeds, in
which the females, as there is reason to believe, originally
acquired a crest, and subsequently transferred it to the males. All
these cases are intelligible on the hypothesis of pangenesis; for they
depend on the gemmules of certain parts, although present in both
sexes, becoming, through the influence of domestication, either
dormant or developed in either sex.
There is one difficult question which it will be convenient to defer
to a future chapter; namely, whether a character at first developed in
both sexes, could through selection be limited in its development to
one sex alone. If, for instance, a breeder observed that some of his
pigeons (of which the characters are usually transferred in an equal
degree to both sexes) varied into pale blue, could he by
long-continued selection make a breed, in which the males alone should
be of this tint, whilst the females remained unchanged? I will here
only say, that this, though perhaps not impossible, would be extremely
difficult; for the natural result of breeding from the pale-blue males
would be to change the whole stock of both sexes to this tint. If,
however, variations of the desired tint appeared, which were from
the first limited in their development to the male sex, there would
not be the least difficulty in making a breed with the two sexes of
a different colour, as indeed has been effected with a Belgian
breed, in which the males alone are streaked with black. In a
similar manner, if any variation appeared in a female pigeon, which
was from the first sexually limited in its development to the females,
it would be easy to make a breed with the females alone thus
characterised; but if the variation was not thus originally limited,
the process would be extremely difficult, perhaps impossible.*
* Since the publication of the first edition of this work, it has
been highly satisfactory to me to find the following remarks (the
Field, Sept., 1872) from so experienced a breeder as Mr. Tegetmeier.
After describing some curious cases in pigeons, of the transmission of
colour by one sex alone, and the formation of a sub-breed with this
character, he says: "It is a singular circumstance that Mr. Darwin
should have suggested the possibility of modifying the sexual
colours of birds by a course of artificial selection. When he did
so, he was in ignorance of these facts that I have related; but it
is remarkable how very closely he suggested the right method of
procedure."
On the Relation between the Period of Development of a Character and
its Transmission to one Sex or to both Sexes.- Why certain
characters should be inherited by both sexes, and other characters
by one sex alone, namely by that sex in which the character first
appeared, is in most cases quite unknown. We cannot even conjecture
why with certain sub-breeds of the pigeon, black striae, though
transmitted through the female, should be developed in the male alone,
whilst every other character is equally transferred to both sexes.
Why, again, with cats, the tortoise-shell colour should, with rare
exceptions, be developed in the female alone. The very same character,
such as deficient or super-numerary digits, colour-blindness, &c., may
with mankind be inherited by the males alone of one family, and in
another family by the females alone, though in both cases
transmitted through the opposite as well as through the same sex.*
Although we are thus ignorant, the two following rules seem often to
hold good- that variations which first appear in either sex at a
late period of life tend to be developed in the same sex alone; whilst
variations which first appear early in life in either sex tend to be
developed in both sexes. I am, however, far from supposing that this
is the sole determining cause. As I have not elsewhere discussed
this subject, and it has an important bearing on sexual selection, I
must here enter into lengthy and somewhat intricate details.
* References are given in my Variation of Animals and Plants under
Domestication, vol. ii., p. 72.
It is in itself probable that any character appearing at an early
age would tend to be inherited equally by both sexes, for the sexes do
not differ much in constitution before the power of reproduction is
gained. On the other hand, after this power has been gained and the
sexes have come to differ in constitution, the gemmules (if I may
again use the language of pangenesis) which are cast off from each
varying part in the one sex would be much more likely to possess the
proper affinities for uniting with the tissues of the same sex, and
thus becoming developed, than with those of the opposite sex.
I was first led to infer that a relation of this kind exists, from
the fact that whenever and in whatever manner the adult male differs
from the adult female, he differs in the same manner from the young of
both sexes. The generality of this fact is quite remarkable: it
holds good with almost all mammals, birds, amphibians, and fishes;
also with many crustaceans, spiders, and some few insects, such as
certain Orthoptera and Libellulae. In all these cases the
variations, through the accumulation of which the male acquired his
proper masculine characters, must have occurred at a somewhat late
period of life; otherwise the young males would have been similarly
characterised; and conformably with our rule, the variations are
transmitted to and developed in the adult males alone. When, on the
other hand, the adult male closely resembles the young of both sexes
(these, with rare exceptions, being alike), he generally resembles the
adult female; and in most of these cases the variations through
which the young and old acquired their present characters, probably
occurred, according to our rule, during youth. But there is here
room for doubt, for characters are sometimes transferred to the
offspring at an earlier age than that at which they first appeared
in the parents, so that the parents may have varied when adult, and
have transferred their characters to their offspring whilst young.
There are, moreover, many animals, in which the two sexes closely
resemble each other, and yet both differ from their young: and here
the characters of the adults must have been acquired late in life;
nevertheless, these characters, in apparent contradiction to our rule,
are transferred to both sexes. We must not however, overlook the
possibility or even probability of successive variations of the same
nature occurring, under exposure to similar conditions, simultaneously
in both sexes at a rather late period of life; and in this case the
variations would be transferred to the offspring of both sexes at a
corresponding late age; and there would then be no real
contradiction to the rule that variations occurring late in life are
transferred exclusively to the sex in which they first appeared.
This latter rule seems to hold true more generally than the second
one, namely, that variations which occur in either sex early in life
tend to be transferred to both sexes. As it was obviously impossible
even to estimate in how large a number of cases throughout the
animal kingdom these two propositions held good, it occurred to me
to investigate some striking or crucial instances, and to rely on
the result.
An excellent case for investigation is afforded by the deer
family. In all the species, but one, the horns are developed only in
the males, though certainly transmitted through the females, and
capable of abnormal development in them. In the reindeer, on the other
hand, the female is provided with horns; so that in this species,
the horns ought, according to our rule, to appear early in life,
long before the two sexes are mature and have come to differ much in
constitution. In all the other species the horns ought to appear later
in life, which would lead to their development in that sex alone, in
which they first appeared in the progenitor of the whole family. Now
in seven species, belonging to distinct sections of the family and
inhabiting different regions, in which the stags alone bear horns, I
find that the horns first appear at periods, varying from nine
months after birth in the roebuck to ten, twelve or even more months
in the stags of the six other and larger species.* But with the
reindeer the case is widely different; for, as I hear from Prof.
Nilsson, who kindly made enquiries for me in Lapland, the horns appear
in the young animals within four or five weeks after birth, and at the
same time in both sexes. So that here we have a structure, developed
at a most unusually early age in one species of the family, and
likewise common to both sexes in this one species alone.
* I am much obliged to Mr. Cupples for having made enquiries for
me in regard to the roebuck and red deer of Scotland from Mr.
Robertson, the experienced head-forester to the Marquis of
Breadalbane. In regard to fallow-deer, I have to thank Mr. Eyton and
others for information. For the Cervus alces of N. America, see Land
and Water, 1868, pp. 221 and 254; and for the C. Virginianus and C.
strongyloceros of the same continent, see J. D. Caton, in Ottawa Acad.
of Nat. Sc., 1868, p. 13. For Cervus eldi of Pegu, see Lieut.
Beaven, Proccedings of the Zoological Society, 1867, p. 762.
In several kinds of antelopes, only the males are provided with
horns, whilst in the greater number both sexes bear horns. With
respect to the period of development, Mr. Blyth informs me that
there was at one time in the Zoological Gardens a young koodoo (A.
strepsiceros), of which the males alone are horned, and also the young
of a closely-allied species, the eland (A. oreas), in which both sexes
are horned. Now it is in strict conformity with our rule, that in
the young male koodoo, although ten months old, the horns were
remarkably small, considering the size ultimately attained by them;
whilst in the young male eland, although only three months old, the
horns were already very much larger than in the koodoo. It is also a
noticeable fact that in the prong-horned antelope,* only a few of
the females, about one in five, have horns, and these are in a
rudimentary state, though sometimes above four inches long: so that as
far as concerns the possession of horns by the males alone, this
species is in an intermediate condition, and the horns do not appear
until about five or six months after birth. Therefore in comparison
with what little we know of the development of the horns in other
antelopes, and from what we do know with respect to the horns of deer,
cattle, &c., those of the prong-horned antelope appear at an
intermediate period of life,- that is, not very early, as in cattle
and sheep, nor very late, as in the larger deer and antelopes. The
horns of sheep, goats, and cattle, which are well developed in both
sexes, though not quite equal in size, can be felt, or even seen, at
birth or soon afterwards.*(2) Our rule, however, seems to fail in some
breeds of sheep, for instance merinos, in which the rams alone are
horned; for I cannot find on enquiry,*(3) that the horns are developed
later in life in this breed than in ordinary sheep in which both sexes
are horned. But with domesticated sheep the presence or absence of
horns is not a firmly fixed character; for a certain proportion of the
merino ewes bear small horns, and some of the rams are hornless; and
in most breeds hornless ewes are occasionally produced.
* Antilocapra Americana. I have to thank Dr. Canfield for
information with respect to the horns of the female: see also his
paper in Proceedings of the Zoological Society, 1866, p. 109. Also
Owen, Anatomy of Vertebrates, vol. iii., p. 627.
*(2) I have been assured that the horns of the sheep in north
Wales can always be felt, and are sometimes even an inch in length, at
birth. Youatt says (Cattle, 1834, p. 277), that the prominence of
the frontal bone in cattle penetrates the cutis at birth, and that the
horny matter is soon formed over it.
*(3) I am greatly indebted to Prof. Victor Carus for having made
enquiries for me, from the highest authorities, with respect to the
merino sheep of Saxony. On the Guinea coast of Africa there is,
however, a breed of sheep in which, as with merinos, the rams alone
bear horns; and Mr. Winwood Reade informs me that in one case observed
by him, a young ram, born on Feb. 10th, first shewed horns on March
6th, so that in this instance, in conformity with rule, the
development of the horns occurred at a later period of life than in
Welsh sheep, in which both sexes are horned.
Dr. W. Marshall has lately made a special study of the protuberances
so common on the heads of birds,* and he comes to the following
conclusion:- that with those species in which they are confined to the
males, they are developed late in life; whereas with those species
in which they are common to the two sexes, they are developed at a
very early period. This is certainly a striking confirmation of my two
laws of inheritance.
* "Uber die knochernen Schadelhocker der Vogel", in the
Niederland. Archiv fur Zoologie, B.i., Heft 2, 1872.
In most of the species of the splendid family of the pheasants,
the males differ conspicuously from the females, and they acquire
their ornaments at a rather late period of life. The eared pheasant
(Crossoptilon auritum), however, offers a remarkable exception, for
both sexes possess the fine caudal plumes, the large ear-tufts and the
crimson velvet about the head; I find that all these characters appear
very early in life in accordance with rule. The adult male can,
however, be distinguished from the adult female by the presence of
spurs; and conformably with our rule, these do not begin to be
developed before the age of six months, as I am assured by Mr.
Bartlett, and even at this age, the two sexes can hardly be
distinguished.* The male and female peacock differ conspicuously
from each other in almost every part of their plumage, except in the
elegant head-crest, which is common to both sexes; and this is
developed very early in life, long before the other ornaments, which
are confined to the male. The wild-duck offers an analogous case,
for the beautiful green speculum on the wings is common to both sexes,
though duller and somewhat smaller in the female, and it is
developed early in life, whilst the curled tail-feathers and other
ornaments of the male are developed later.*(2) Between such extreme
cases of close sexual resemblance and wide dissimilarity, as those
of the Crossoptilon and peacock, many intermediate ones could be
given, in which the characters follow our two rules in their order
of development.
* In the common peacock (Pavo cristatus) the male alone possesses
spurs, whilst both sexes of the Java peacock (P. muticus) offer the
unusual case of being furnished with spurs. Hence I fully expected
that in the latter species they would have been developed earlier in
life than in the common peacock; but M. Hegt of Amsterdam informs
me, that with young birds of the previous year, of both species,
compared on April 23rd, 1869, there was no difference in the
development of the spurs. The spurs, however, were as yet
represented merely by slight knobs or elevations. I presume that I
should have been informed if any difference in the rate of development
had been observed subsequently.
*(2) In some other species of the duck family the speculum differs
in a greater degree in the two sexes; but I have not been able to
discover whether its full development occurs later in life in the
males of such species, than in the male of the common duck, as ought
to be the case according to our rule. With the allied Mergus
cucullatus we have, however, a case of this kind: the two sexes differ
conspicuously in general plumage, and to a considerable degree in
the speculum, which is pure white in the male and greyish-white in the
female. Now the young males at first entirely resemble the females,
and have a greyish-white speculum, which becomes pure white at an
earlier age than that at which the adult male acquires his other and
more strongly-marked sexual differences: see Audubon, Ornithological
Biography, vol. iii., 1835, pp. 249-250.
As most insects emerge from the pupal state in a mature condition,
it is doubtful whether the period of development can determine the
transference of their characters to one or to both sexes. But we do
not know that the coloured scales, for instance, in two species of
butterflies, in one of which the sexes differ in colour, whilst in the
other they are alike, are developed at the same relative age in the
cocoon. Nor do we know whether all the scales are simultaneously
developed on the wings of the same species of butterfly, in which
certain coloured marks are confined to one sex, whilst others are
common to both sexes. A difference of this kind in the period of
development is not so improbable as it may at first appear; for with
the Orthoptera, which assume their adult state, not by a single
metamorphosis, but by a succession of moults, the young males of
some species at first resemble the females, and acquire their
distinctive masculine characters only at a later moult. Strictly
analogous cases occur at the successive moults of certain male
crustaceans.
We have as yet considered the transference of characters, relatively
to their period of development, only in species in a natural state; we
will now turn to domesticated animals, and first touch on
monstrosities and diseases. The presence of supernumerary digits,
and the absence of certain phalanges, must be determined at an early
embryonic period- the tendency to profuse bleeding is at least
congenital, as is probably colour-blindness- yet these
peculiarities, and other similar ones, are often limited in their
transmission to one sex; so that the rule that characters, developed
at an early period, tend to be transmitted to both sexes, here
wholly fails. But this rule, as before remarked, does not appear to be
nearly so general as the converse one, namely, that characters which
appear late in life in one sex are transmitted exclusively to the same
sex. From the fact of the above abnormal peculiarities becoming
attached to one sex, long before the sexual functions are active, we
may infer that there must be some difference between the sexes at an
extremely early age. With respect to sexually-limited diseases, we
know too little of the period at which they originate, to draw any
safe conclusion. Gout, however, seems to fall under our rule, for it
is generally caused by intemperance during manhood, and is transmitted
from the father to his sons in a much more marked manner than to his
daughters.
In the various domestic breeds of sheeps, goats, and cattle, the
males differ from their respective females in the shape or development
of their horns, forehead, mane, dewlap, tail, and hump on the
shoulders; and these peculiarities, in accordance with our rule, are
not fully developed until a rather late period of life. The sexes of
dogs do not differ, except that in certain breeds, especially in the
Scotch deerhound, the male is much larger and heavier than the female;
and, as we shall see in a future chapter, the male goes on
increasing in size to an unusually late period of life, which,
according to rule, will account for his increased size being
transmitted to his male offspring alone. On the other hand, the
tortoise-shell colour, which is confined to female cats, is quite
distinct at birth, and this case violates the rule. There is a breed
of pigeons in which the males alone are streaked with black, and the
streaks can be detected even in the nestlings; but they become more
conspicuous at each successive moult, so that this case partly opposes
and partly supports the rule. With the English carrier and pouter
pigeons, the full development of the wattle and the crop occurs rather
late in life, and conformably with the rule, these characters are
transmitted in full perfection to the males alone. The following cases
perhaps come within the class previously alluded to, in which both
sexes have varied in the same manner at a rather late period of
life, and have consequently transferred their new characters to both
sexes at a corresponding late period; and if so, these cases are not
opposed to our rule:- there exist sub-breeds of the pigeon,
described by Neumeister,* in which both sexes change their colour
during two or three moults (as is likewise the case with the almond
tumbler); nevertheless, these changes, though occurring rather late in
life, are common to both sexes. One variety of the canary-bird, namely
the London Prize, offers a nearly analogous case.
* Das Ganze der Taubenzucht, 1837, ss. 21, 24. For the case of the
streaked pigeons, see Dr. Chapuis, Le Pigeon Voyageur Belge, 1855,
p. 87.
With the breeds of the fowl the inheritance of various characters by
one or both sexes, seems generally determined by the period at which
such characters are developed. Thus in all the many breeds in which
the adult male differs greatly in colour from the female, as well as
from the wild parent-species, he differs also from the young male,
so that the newly-acquired characters must have appeared at a rather
late period of life. On the other hand, in most of the breeds in which
the two sexes resemble each other, the young are coloured in nearly
the same manner as their parents, and this renders it probable that
their colours first appeared early in life. We have instances of
this fact in all black and white breeds, in which the young and old of
both sexes are alike; nor can it be maintained that there is something
peculiar in a black or white plumage, which leads to its
transference to both sexes; for the males alone of many natural
species are either black or white, the females being differently
coloured. With the so-called cuckoo sub-breeds of the fowl, in which
the feathers are transversely pencilled with dark stripes, both
sexes and the chickens are coloured in nearly the same manner. The
laced plumage of the Sebright bantam is the same in both sexes, and in
the young chickens the wing-feathers are distinctly, though
imperfectly laced. Spangled Hamburgs, however, offer a partial
exception; for the two sexes, though not quite alike, resemble each
other more closely than do the sexes of the aboriginal parent-species;
yet they acquire their characteristic plumage late in life, for the
chickens are distinctly pencilled. With respect to other characters
beside colour, in the wild-parent species and in most of the
domestic breeds, the males alone possess a well-developed comb; but in
the young of the Spanish fowl it is largely developed at a very
early age, and, in accordance with this early development in the male,
it is of unusual size in the adult female. In the game breeds
pugnacity is developed at a wonderfully early age, of which curious
proofs could be given; and this character is transmitted to both
sexes, so that the hens, from their extreme pugnacity, are now
generally exhibited in separate pens. With the Polish breeds the
bony protuberance of the skull which supports the crest is partially
developed even before the chickens are hatched, and the crest itself
soon begins to grow, though at first feebly;* and in this breed the
adults of both sexes are characterised by a great bony protuberance
and an immense crest.
* For full particulars and references on all these points respecting
the several breeds of the fowl, see Variation of Animals and Plants
under Domestication, vol. i., pp. 250, 256. In regard to the higher
animals, the sexual differences which have arisen under
domestication are described in the same work under the head of each
species.
Finally, from what we have now seen of the relation which exists
in many natural species and domesticated races, between the period
of the development of their characters and the manner of their
transmission- for example, the striking fact of the early growth of
the horns in the reindeer, in which both sexes bear horns, in
comparison with their much later growth in the other species in
which the male alone bears horns- we may conclude that one, though not
the sole cause of characters being exclusively inherited by one sex,
is their development at a late age. And secondly, that one, though
apparently a less efficient cause of characters being inherited by
both sexes, is their development at an early age, whilst the sexes
differ but little in constitution. It appears, however, that some
difference must exist between the sexes even during a very early
embryonic period, for characters developed at this age not rarely
become attached to one sex.
Summary and concluding remarks.- From the foregoing discussion on
the various laws of inheritance, we learn that the characters of the
parents often, or even generally, tend to become developed in the
offspring of the same sex, at the same age, and periodically at the
same season of the year, in which they first appeared in the
parents. But these rules, owing to unknown causes, are far from
being fired. Hence during the modification of a species, the
successive changes may readily be transmitted in different ways;
some to one sex, and some to both; some to the offspring at one age,
and some to the offspring at all ages. Not only are the laws of
inheritance extremely complex, but so are the causes which induce
and govern variability. The variations thus induced are preserved
and accumulated by sexual selection, which is in itself an extremely
complex affair, depending, as it does, on the ardour in love, the
courage, and the rivalry of the males, as well as on the powers of
perception, the taste, and will of the female. Sexual selection will
also be largely dominated by natural selection tending towards the
general welfare of the species. Hence the manner in which the
individuals of either or both sexes have been affected through
sexual selection cannot fail to be complex in the highest degree.
When variations occur late in life in one sex, and are transmitted
to the same sex at the same age, the other sex and the young are
left unmodified. When they occur late in life, but are transmitted
to both sexes at the same age, the young alone are left unmodified.
Variations, however, may occur at any period of life in one sex or
in both, and be transmitted to both sexes at all ages, and then all
the individuals of the species are similarly modified. In the
following chapters it will be seen that all these cases frequently
occur in nature.
Sexual selection can never act on any animal before the age for
reproduction arrives. From the great eagerness of the male it has
generally acted on this sex and not on the females. The males have
thus become provided with weapons for fighting with their rivals, with
organs for discovering and securely holding the female, and for
exciting or charming her. When the sexes differ in these respects,
it is also, as we have seen, an extremely general law that the adult
male differs more or less from the young male; and we may conclude
from this fact that the successive variations, by which the adult male
became modified, did not generally occur much before the age for
reproduction. Whenever some or many of the variations occurred early
in life, the young males would partake more or less of the
characters of the adult males; and differences of this kind between
the old and young males may be observed in many species of animals.
It is probable that young male animals have often tended to vary
in a manner which would not only have been of no use to them at an
early age, but would have been actually injurious- as by acquiring
bright colours, which would render them conspicuous to their
enemies, or by acquiring structures, such as great horns, which
would expend much vital force in their development. Variations of this
kind occurring in the young males would almost certainly be eliminated
through natural selection. With the adult and experienced males, on
the other hand, the advantages derived from the acquisition of such
characters, would more than counterbalance some exposure to danger,
and some loss of vital force.
As variations which give to the male a better chance of conquering
other males, or of finding, securing, or charming the opposite sex,
would, if they happened to arise in the female, be of no service to
her, they would not be preserved in her through sexual selection. We
have also good evidence with domesticated animals, that variations
of all kinds are, if not carefully selected, soon lost through
inter-crossing and accidental deaths. Consequently in a state of
nature, if variations of the above kind chanced to arise in the female
line, and be transmitted exclusively in this line, they would be
extremely liable to be lost. If, however, the females varied and
transmitted their newly acquired characters to their offspring of both
sexes, the characters which were advantageous to the males would be
preserved by them through sexual selection, and the two sexes would in
consequence be modified in the same manner, although such characters
were of no use to the females: but I shall hereafter have to recur
to these more intricate contingencies. Lastly, the females may
acquire, and apparently have often acquired by transference,
characters from the male sex.
As variations occurring later in life, and transmitted to one sex
alone, have incessantly been taken advantage of and accumulated
through sexual selection in relation to the reproduction of the
species; therefore it appears, at first sight, an unaccountable fact
that similar variations have not frequently been accumulated through
natural selection, in relation to the ordinary habits of life. If this
had occurred, the two sexes would often have been differently
modified, for the sake, for instance, of capturing prey or of escaping
from danger. Differences of this kind between the two sexes do
occasionally occur, especially in the lower classes. But this
implies that the two sexes follow different habits in their
struggles for existence, which is a rare circumstance with the
higher animals. The case, however, is widely different with the
reproductive functions, in which respect the sexes necessarily differ.
For variations in structure which are related to these functions, have
often proved of value to one sex, and from having arisen at a late
period of life, have been transmitted to one sex alone; and such
variations, thus preserved and transmitted, have given rise to
secondary sexual characters.
In the following chapters, I shall treat of the secondary sexual
characters in animals of all classes, and shall endeavour in each case
to apply the principles explained in the present chapter. The lowest
classes will detain us for a very short time, but the higher
animals, especially birds, must be treated at considerable length.
It should be borne in mind that for reasons already assigned, I intend
to give only a few illustrative instances of the innumerable
structures by the aid of which the male finds the female, or, when
found, holds her. On the other hand, all structures and instincts by
the aid of which the male conquers other males, and by which he
allures or excites the female, will be fully discussed, as these are
in many ways the most interesting.
Supplement on the proportional numbers of the two sexes in animals
belonging to various classes.
As no one, as far as I can discover, has paid attention to the
relative numbers of the two sexes throughout the animal kingdom, I
will here give such materials as I have been able to collect, although
they are extremely imperfect. They consist in only a few instances
of actual enumeration, and the numbers are not very large. As the
proportions are known with certainty only in mankind, I will first
give them as a standard of comparison.
Man.- In England during ten years (from 1857 to 1866) the average
number of children born alive yearly was 707,120, in the proportion of
104.5 males to 100 females. But in 1857 the male births throughout
England were as 105.2, and in 1865 as 104.0 to 100. Looking to
separate districts, in Buckinghamshire (where about 5000 children
are annually born) the mean proportion of male to female births,
during the whole period of the above ten years, was as 102.8 to 100;
whilst in N. Wales (where the average annual births are 12,873) it was
as high as 106.2 to 100. Taking a still smaller district, viz.,
Rutlandshire (where the annual births average only 739), in 1864 the
male births were as 114.6, and in 1862 as only 97.0 to 100; but even
in this small district the average of the 7385 births during the whole
ten years, was as 104.5 to 100: that is in the same ratio as
throughout England.* The proportions are sometimes slightly
disturbed by unknown causes; thus Prof. Faye states "that in some
districts of Norway there has been during a decennial period a
steady deficiency of boys, whilst in others the opposite condition has
existed." In France during forty-four years the male to the female
births have been as 106.2 to 100; but during this period it has
occurred five times in one department, and six times in another,
that the female births have exceeded the males. In Russia the
average proportion is as high as 108.9, and in Philadelphia in the
United States as 110.5 to 100.*(2) The average for Europe, deduced
by Bickes from about seventy million births, is 106 males to 100
females. On the other hand, with white children born at the Cape of
Good Hope, the proportion of males is so low as to fluctuate during
successive years between 90 and 99 males for every 100 females. It
is a singular fact that with Jews the proportion of male births is
decidedly larger than with Christians: thus in Prussia the
proportion is as 113, in Breslau as 114, and in Livonia as 120 to 100;
the Christian births in these countries being the same as usual, for
instance, in Livonia as 104 to 100.*(3)
* Twenty-ninth Annual Report of the Registrar-General for 1866. In
this report (p. xii.) a special decennial table is given.
*(2) For Norway and Russia, see abstract of Prof. Faye's researches,
in British and Foreign Medico-Chirurg. Review, April, 1867, pp. 343,
345. For France, the Annuaire pour l'An 1867, p. 213. For
Philadelphia, Dr. Stockton-Hough, Social Science Assoc., 1874. For the
Cape of Good Hope, Quetelet as quoted by Dr. H. H. Zouteveen, in the
Dutch translation of this work (vol. i., p. 417), where much
information is given on the proportion of the sexes.
*(3) In regard to the Jews, see M. Thury, La Loi de Production des
Sexes, 1863, p. 25.
Prof. Faye remarks that "a still greater preponderance of males
would be met with, if death struck both sexes in equal proportion in
the womb and during birth. But the fact is, that for every 100
still-born females, we have in several countries from 134.6 to 144.9
stillborn males. During the first four or five years of life, also,
more male children die than females, for example in England, during
the first year, 126 boys die for every 100 girls- a proportion which
in France is still more unfavourable."* Dr. Stockton-Hough accounts
for these facts in part by the more frequent defective development
of males than of females. We have before seen that the male sex is
more variable in structure than the female; and variations in
important organs would generally be injurious. But the size of the
body, and especially of the head, being greater in male than female
infants is another cause: for the males are thus more liable to be
injured during parturition. Consequently the still-born males are more
numerous; and, as a highly competent judge, Dr. Crichton Browne,*(2)
believes, male infants often suffer in health for some years after
birth. Owing to this excess in the death-rate of male children, both
at birth and for some time subsequently, and owing to the exposure
of grown men to various dangers, and to their tendency to emigrate,
the females in all old-settled countries, where statistical records
have been kept,*(3) are found to preponderate considerably over the
males.
* British and Foreign Medico-Chirurg. Review, April, 1867, p. 343.
Dr. Stark also remarks (Tenth Annual Reports of Births, Deaths, &c.,
in Scotland, 1867, p. xxviii.) that "These examples may suffice to
show that, at almost every stage of life, the males in Scotland have a
greater liability to death and a higher death-rate than the females.
The fact, however, of this peculiarity being most strongly developed
at that infantile period of life when the dress, food, and general
treatment of both sexes are alike, seems to prove that the higher male
death-rate is an impressed, natural, and constitutional peculiarity
due to sex alone."
*(2) West Riding Lunatic Asylum Reports, vol. i., 1871, p. 8. Sir J.
Simpson has proved that the head of the male infant exceeds that of
the female by 3/8ths of an inch in circumference, and by 1/8th in
transverse diameter. Quetelet has shown that woman is born smaller
than man; see Dr. Duncan, Fecundity, Fertility, and Sterility, 1871,
p. 382.
*(3) With the savage Guaranys of Paraguay, according to the accurate
Azara (Voyages dans l'Amerique merid., tom. ii., 1809, pp. 60, 179),
the women are to the men in the proportion of 14 to 13.
It seems at first sight a mysterious fact that in different nations,
under different conditions and climates, in Naples, Prussia,
Westphalia, Holland, France, England and the United States, the excess
of male over female births is less when they are illegitimate than
when legitimate.* This has been explained by different writers in many
different ways, as from the mothers being generally young, from the
large proportion of first pregnancies, &c. But we have seen that
male infants, from the large size of their heads, suffer more than
female infants during parturition; and as the mothers of
illegitimate children must be more liable than other women to
undergo bad labours, from various causes, such as attempts at
concealment by tight lacing, hard work, distress of mind, &c., their
male infants would proportionably suffer. And this probably is the
most efficient of all the causes of the proportion of males to females
born alive being less amongst illegitimate children than amongst the
legitimate. With most animals the greater size of the adult male
than of the female, is due to the stronger males having conquered
the weaker in their struggles for the possession of the females, and
no doubt it is owing to this fact that the two sexes of at least
some animals differ in size at birth. Thus we have the curious fact
that we may attribute the more frequent deaths of male than female
infants, especially amongst the illegitimate, at least in part to
sexual selection.
* Babbage, Edinburgh Journal of Science, 1829, vol. i., p. 88;
also p. 90, on still-born children. On illegitimate children in
England, see Report of Registrar-General for 1866, p. xv.
It has often been supposed that the relative age of the two
parents determine the sex of the offspring; and Prof. Leuckart* has
advanced what he considers sufficient evidence, with respect to man
and certain domesticated animals, that this is one important though
not the sole factor in the result. So again the period of impregnation
relatively to the state of the female has been thought by some to be
the efficient cause; but recent observations discountenance this
belief. According to Dr. Stockton-Hough,*(2) the season of the year,
the poverty or wealth of the parents, residence in the country or in
cities, the crossing of foreign immigrants, &c., all influence the
proportion of the sexes. With mankind, polygamy has also been supposed
to lead to the birth of a greater proportion of female infants; but
Dr. J. Campbell*(3) carefully attended to this subject in the harems
of Siam, and concludes that the proportion of male to female births is
the same as from monogamous unions. Hardly any animal has been
rendered so highly polygamous as the English race-horse, and we
shall immediately see that his male and female offspring are almost
exactly equal in number. I will now give the facts which I have
collected with respect to the proportional numbers of the sexes of
various animals; and will then briefly discuss how far selection has
come into play in determining the result.
* Leuckart, in Wagner's Handworterbuch der Phys., B. iv., 1853, s.
774.
*(2) Social Science Association of Philadelphia, 1874.
*(3) Anthropological Review, April, 1870, p. cviii.
Horses.- Mr. Tegetmeier has been so kind as to tabulate for me
from the Racing Calendar the births of race-horses during a period
of twenty-one years, viz., from 1846 to 1867; 1849 being omitted, as
no returns were that year published. The total births were 25,560,*
consisting of 12,763 males and 12,797 females, or in the proportion of
99.7 males to 100 females. As these numbers are tolerably large, and
as they are drawn from all parts of England, during several years,
we may with much confidence conclude that with the domestic horse,
or at least with the race-horse, the two sexes are produced in
almost equal numbers. The fluctuations in the proportions during
successive years are closely like those which occur with mankind, when
a small and thinly-populated area is considered; thus in 1856 the male
horses were as 107.1, and in 1867 as only 92.6 to 100 females. In
the tabulated returns the proportions vary in cycles, for the males
exceeded the females during six successive years; and the females
exceeded the males during two periods each of four years; this,
however, may be accidental; at least I can detect nothing of the
kind with man in the decennial table in the Registrar's Report for
1866.
* During eleven years a record was kept of the number of mares which
proved barren or prematurely slipped their foals; and it deserves
notice, as shewing how infertile these highly-nurtured and rather
closely-interbred animals have become, that not far from one-third
of the mares failed to produce living foals. Thus during 1866, 809
male colts and 816 female colts were born, and 743 mares failed to
produce offspring. During 1867, 836 males and 902 females were born,
and 794 mares failed.
Dogs.- During a period of twelve years, from 1857 to 1868, the
births of a large number of greyhounds, throughout England, were
sent to the Field newspaper; and I am again indebted to Mr. Tegetmeier
for carefully tabulating the results. The recorded births were 6878,
consisting of 3605 males and 3273 females, that is, in the
proportion of 110.1 males to 100 females. The greatest fluctuations
occurred in 1864, when the proportion was as 95.3 males, and in
1867, as 116.3 males to 100 females. The above average proportion of
110.1 to 100 is probably nearly correct in the case of the
greyhound, but whether it would hold with other domesticated breeds is
in some degree doubtful. Mr. Cupples has enquired from several great
breeders of dogs, and finds that all without exception believe that
females are produced in excess; but he suggests that this belief may
have arisen from females being less valued, and from the consequent
disappointment producing a stronger impression on the mind.
Sheep.- The sexes of sheep are not ascertained by agriculturists
until several months after birth, at the period when the males are
castrated; so that the following returns do not give the proportions
at birth. Moreover, I find that several great breeders in Scotland,
who annually raise some thousand sheep, are firmly convinced that a
larger proportion of males than of females die during the first year
or two. Therefore the proportion of males would be somewhat larger
at birth than at the age of castration. This is a remarkable
coincidence with what, as we have seen, occurs with mankind, and
both cases probably depend on the same cause. I have received
returns from four gentlemen in England who have bred lowland sheep,
chiefly Leicesters, during the last ten to sixteen years; they
amount altogether to 8965 births, consisting of 4407 males and 4558
females; that is in the proportion of 96.7 males to 100 females.
With respect to Cheviot and black-faced sheep bred in Scotland, I have
received returns from six breeders, two of them on a large scale,
chiefly for the years 1867-1869, but some of the returns extend back
to 1862. The total number recorded amounts to 50,685, consisting of
25,071 males and 25,614 females or in the proportion of 97.9 males
to 100 females. If we take the English and Scotch returns together,
the total number amounts to 59,650, consisting of 29,478 males and
30,172 females, or as 97.7 to 100. So that with sheep at the age of
castration the females are certainly in excess of the males, but
probably this would not hold good at birth.*
*I am much indebted to Mr. Cupples for having procured for me the
above returns from Scotland, as well as some of the following
returns on cattle. Mr. R. Elliot, of Laighwood, first called my
attention to the premature deaths of the males,- a statement
subsequently confirmed by Mr. Aitchison and others. To this latter
gentleman, and to Mr. Payan, I owe my thanks for large returns as to
sheep.
Of Cattle I have received returns from nine gentlemen of 982 births,
too few to be trusted; these consisted of 477 bull-calves and 505
cow-calves; i.e., in the proportion of 94.4 males to 100 females.
The Rev. W. D. Fox informs me that in 1867 out of 34 calves born on
a farm in Derbyshire only one was a bull. Mr. Harrison Weir has
enquired from several breeders of Pigs, and most of them estimate
the male to the female births as about 7 to 6. This same gentleman has
bred rabbits for many years, and has noticed that a far greater number
of bucks are produced than does. But estimations are of little value.
Of Mammalia in a state of nature I have been able to learn very
little. In regard to the common rat, I have received conflicting
statements. Mr. R. Elliot, of Laighwood, informs me that a rat-catcher
assured him that he had always found the males in great excess, even
with the young in the nest. In consequence of this, Mr. Elliot himself
subsequently examined some hundred old ones, and found the statement
true. Mr. F. Buckland has bred a large number of white rats, and he
also believes that the males greatly exceed the females. In regard
to moles, it is said that "the males are much more numerous than the
females":* and as the catching of these animals is a special
occupation, the statement may perhaps be trusted. Sir A. Smith, in
describing an antelope of S. Africa*(2) (Kobus ellipsiprymnus),
remarks, that in the herds of this and other species, the males are
few in number compared with the females: the natives believe that they
are born in this proportion; others believe that the younger males are
expelled from the herds, and Sir A. Smith says, that though he has
himself never seen herds consisting of young males alone, others
affirm that this does occur. It appears probable that the young when
expelled from the herd, would often fall a prey to the many beasts
of prey of the country.
* Bell, History of British Quadrupeds, p. 100.
*(2) Illustrations of the Zoology of S. Africa, 1849, pl. 29.
BIRDS.
With respect to the Fowl, I have received only one account,
namely, that out of 1001 chickens of a highly-bred stock of Cochins,
reared during eight years by Mr. Stretch, 487 proved males and 514
females; i.e., as 94.7 to 100. In regard to domestic pigeons there
is good evidence either that the males are produced in excess, or that
they live longer; for these birds invariably pair, and single males,
as Mr. Tegetmeier informs me, can always be purchased cheaper than
females. Usually the two birds reared from the two eggs laid in the
same nest are a male and a female; but Mr. Harrison Weir, who has been
so large a breeder, says that he has often bred two cocks from the
same nest, and seldom two hens; moreover, the hen is generally the
weaker of the two, and more liable to perish.
With respect to birds in a state of nature, Mr. Gould and others*
are convinced that the males are generally the more numerous; and as
the young males of many species resemble the females, the latter would
naturally appear to be the more numerous. Large numbers of pheasants
are reared by Mr. Baker of Leadenhall from eggs laid by wild birds,
and he informs Mr. Jenner Weir that four or five males to one female
are generally produced. An experienced observer remarks,*(2) that in
Scandinavia the broods of the capercailzie and black-cock contain more
males than females; and that with the Dal-ripa (a kind of ptarmigan)
more males than females attend the leks or places of courtship; but
this latter circumstance is accounted for by some observers by a
greater number of hen birds being killed by vermin. From various facts
given by White of Selborne,*(3) it seems clear that the males of the
partridge must be in considerable excess in the south of England;
and I have been assured that this is the case in Scotland. Mr. Weir on
enquiring from the dealers, who receive at certain seasons large
numbers of ruffs (Machetes pugnax), was told that the males are much
the more numerous. This same naturalist has also enquired for me
from the birdcatchers, who annually catch an astonishing number of
various small species alive for the London market, and he was
unhesitatingly answered by an old and trustworthy man, that with the
chaffinch the males are in large excess: he thought as high as 2 males
to 1 female, or at least as high as 5 to 3.*(4) The males of the
blackbird, he likewise maintained, were by far the more numerous,
whether caught by traps or by netting at night. These statements may
apparently be trusted, because this same man said that the sexes are
about equal with the lark, the twite (Linaria montana), and goldfinch.
On the other hand, he is certain that with the common linnet, the
females preponderate greatly, but unequally during different years;
during some years he has found the females to the males as four to
one. It should, however, be borne in mind, that the chief season for
catching birds does not begin till September, so that with some
species partial migrations may have begun, and the flocks at this
period often consist of hens alone. Mr. Salvin paid particular
attention to the sexes of the humming-birds in Central America, and is
convinced that with most of the species the males are in excess;
thus one year he procured 204 specimens belonging to ten species,
and these consisted of 166 males and of only 38 females. With two
other species the females were in excess: but the proportions
apparently vary either during different seasons or in different
localities; for on one occasion the males of Campylopterus
hemileucurus were to the females as 5 to 2, and on another
occasion*(5) in exactly the reversed ratio. As bearing on this
latter point, I may add, that Mr. Powys found in Corfu and Epirus
the sexes of the chaffinch keeping apart, and "the females by far
the most numerous"; whilst in Palestine Mr. Tristram found "the male
flocks appearing greatly to exceed the female in number."*(6) So again
with the Quiscalus major, Mr. G. Taylor says, that in Florida there
were "very few females in proportion to the males,"*(7) whilst in
Honduras the proportion was the other way, the species there having
the character of a polygamist.
* Brehm (Illustriertes Thierleben, B. iv., s. 990) comes to the same
conclusion.
*(2) On the authority of L. Lloyd, Game Birds of Sweden, 1867, pp.
12, 132.
*(3) Nat. Hist. of Selborne, letter xxix., ed. of 1825, vol. i.,
p. 139.
*(4) Mr. Jenner Weir received similar information, on making
enquiries during the following year. To shew the number of living
chaffinches caught, I may mention that in 1869 there was a match
between two experts, and one man caught in a day 62, and another 40,
male chaffinches. The greatest number ever caught by one man in a
single day was 70.
*(5) Ibis, vol. ii. p. 260, as quoted in Gould's Trochilidae,
1861, p. 52. For the foregoing proportions, I am indebted to Mr.
Salvin for a table of his results.
*(6) Ibis, 1860, p. 137; and 1867, p. 369.
*(7) Ibis, 1862, p. 187.
FISH.
With fish the proportional numbers of the sexes can be ascertained
only by catching them in the adult or nearly adult state; and there
are many difficulties in arriving at any just conclusion.* Infertile
females might readily be mistaken for males, as Dr. Gunther has
remarked to me in regard to trout. With some species the males are
believed to die soon after fertilising the ova. With many species
the males are of much smaller size than the females, so that a large
number of males would escape from the same net by which the females
were caught. M. Carbonnier,*(2) who has especially attended to the
natural history of the pike (Esox lucius), states that many males,
owing to their small size, are devoured by the larger females; and
he believes that the males of almost all fish are exposed from this
same cause to greater danger than the females. Nevertheless, in the
few cases in which the proportional numbers have been actually
observed, the males appear to be largely in excess. Thus Mr. R. Buist,
the superintendent of the Stormontfield experiments, says that in
1865, out of 70 salmon first landed for the purpose of obtaining the
ova, upwards of 60 were males. In 1867 he again "calls attention to
the vast disproportion of the males to the females. We had at the
outset at least ten males to one female." Afterwards females
sufficient for obtaining ova were procured. He adds, "from the great
proportion of the males, they are constantly fighting and tearing each
other on the spawning-beds."*(3) This disproportion, no doubt, can
be accounted for in part, but whether wholly is doubtful, by the males
ascending the rivers before the females. Mr. F. Buckland remarks in
regard to trout, that "it is a curious fact that the males
preponderate very largely in number over the females. It invariably
happens that when the first rush of fish is made to the net, there
will be at least seven or eight males to one female found captive. I
cannot quite account for this; either the males are more numerous than
the females, or the latter seek safety by concealment rather than
flight." He then adds, that by carefully searching the banks
sufficient females for obtaining ova can be found.*(4) Mr. H. Lee
informs me that out of 212 trout taken for this purpose in Lord
Portsmouth's park, 150 were males and 62 females.
* Leuckart quotes Bloch (Wagner, Handworterbuch der Phys., B. iv.,
1853, s. 775), that with fish there are twice as many males as
females.
*(2) Quoted in the Farmer, March 18, 1869, p. 369.
*(3) The Stormontfield Piscicultural Experiments, 1866, p. 23. The
Field newspaper, June 29, 1867.
*(4) Land and Water, 1868, p. 41.
The males of the Cyprinidae likewise seem to be in excess; but
several members of this family, viz., the carp, tench, bream and
minnow, appear regularly to follow the practice, rare in the animal
kingdom, of polyandry; for the female whilst spawning is always
attended by two males, one on each side, and in the case of the
bream by three or four males. This fact is so well known, that it is
always recommended to stock a pond with two male tenches to one
female, or at least with three males to two females. With the
minnow, an excellent observer states, that on the spawning-beds the
males are ten times as numerous as the females; when a female comes
amongst the males, "she is immediately pressed closely by a male on
each side; and when they have been in that situation for a time, are
superseded by other two males."*
* Yarrell, Hist. British Fishes, vol. i., 1826, p. 307; on the
Cyprinus carpio, p. 331; on the Tinca vulgaris, p. 331; on the Abramis
brama, p. 336. See, for the minnow (Leuciscus phoxinus), Loudon's
Magazine of Natural History, vol. v., 1832, p. 682.
INSECTS.
In this great class, the Lepidoptera almost alone affords means
for judging of the proportional numbers of the sexes; for they have
been collected with special care by many good observers, and have been
largely bred from the egg or caterpillar state. I had hoped that
some breeders of silk-moths might have kept an exact record, but after
writing to France and Italy, and consulting various treatises, I
cannot find that this has ever been done. The general opinion
appears to be that the sexes are nearly equal, but in Italy, as I hear
from Professor Canestrini, many breeders are convinced that the
females are produced in excess. This same naturalist, however, informs
me, that in the two yearly broods of the ailanthus silk-moth (Bombyx
cynthia), the males greatly preponderate in the first, whilst in the
second the two sexes are nearly equal, or the females rather in
excess.
In regard to butterflies in a state of nature, several observers
have been much struck by the apparently enormous preponderance of
the males.* Thus Mr. Bates,*(2) in speaking of several species,
about a hundred in number, which inhabit the upper Amazons, says
that the males are much more numerous than the females, even in the
proportion of a hundred to one. In North America, Edwards, who had
great experience, estimates in the genus Papilio the males to the
females as four to one; and Mr. Walsh, who informs me of this
statement, says that with P. turnus this is certainly the case. In
South Africa, Mr. R. Trimen found the males in excess in 19
species;*(3) and in one of these, which swarms in open places, he
estimated the number of males as fifty to one female. With another
species, in which the males are numerous in certain localities, he
collected only five females during seven years. In the island of
Bourbon, M. Maillard states that the males of one species of Papilio
are twenty times as numerous as the females.*(4) Mr. Trimen informs me
that as far as he has himself seen, or heard from others, it is rare
for the females of any butterfly to exceed the males in number; but
three South African species perhaps offer an exception. Mr.
Wallace*(5) states that the females of Ornithoptera croesus, in the
Malay Archipelago, are more common and more easily caught than the
males; but this is a rare butterfly. I may here add, that in
Hyperythra, a genus of moths, Guenee says, that from four to five
females are sent in collections from India for one male.
* Leuckart quotes Meinecke (Wagner, Handworterbuch der Phys., B.
iv., 1853, s. 775) that the males of butterflies are three or four
times as numerous as the females.
*(2) The Naturalist on the Amazons, vol. ii., 1863, pp. 228, 347.
*(3) Four of these cases are given by Mr. Trimen in his
Rhopalocera Africae Australis.
*(4) Quoted by Trimen, Transactions of the Ent. Society, vol. v.,
part iv., 1866, p. 330.
*(5) Transactions, Linnean Society, vol. xxv., p. 37.
When this subject of the proportional numbers of the sexes of
insects was brought before the Entomological Society,* it was
generally admitted that the males of most Lepidoptera, in the adult or
imago state, are caught in greater numbers than the females: but
this fact was attributed by various observers to the more retiring
habits of the females, and to the males emerging earlier from the
cocoon. This latter circumstance is well known to occur with most
Lepidoptera, as well as with other insects. So that, as M. Personnat
remarks, the males of the domesticated Bombyx yamamai., are useless at
the beginning of the season, and the females at the end, from the want
of mates.*(2) I cannot, however, persuade myself that these causes
suffice to explain the great excess of males, in the above cases of
certain butterflies which are extremely common in their native
countries. Mr. Stainton, who has paid very close attention during many
years to the smaller moths, informs me that when he collected them
in the imago state, he thought that the males were ten times as
numerous as the females, but that since he has reared them on a
large scale from the caterpillar state, he is convinced that the
females are the more numerous. Several entomologists concur in this
view. Mr. Doubleday, however, and some others, take an opposite
view, and are convinced that they have reared from the eggs and
caterpillars a larger proportion of males than of females.
* Proceedings, Entomological Society, Feb. 17, 1868.
*(2) Quoted by Dr. Wallace in Proceedings, Entomological Society,
3rd series, vol. v., 1867, p. 487.
Besides the more active habits of the males, their earlier emergence
from the cocoon, and in some cases their frequenting more open
stations, other causes may be assigned for an apparent or real
difference in the proportional numbers of the sexes of Lepidoptera,
when captured in the imago state, and when reared from the egg or
caterpillar state. I hear from Professor Canestrini, that it is
believed by many breeders in Italy, that the female caterpillar of the
silk-moth suffers more from the recent disease than the male; and
Dr. Staudinger informs me that in rearing Lepidoptera more females die
in the cocoon than males. With many species the female caterpillar
is larger than the male, and a collector would naturally choose the
finest specimens, and thus unintentionally collect a larger number
of females. Three collectors have told me that this was their
practice; but Dr. Wallace is sure that most collectors take all the
specimens which they can find of the rarer kinds, which alone are
worth the trouble of rearing. Birds when surrounded by caterpillars
would probably devour the largest; and Professor Canestrini informs me
that in Italy some breeders believe, though on insufficient
evidence, that in the first broods of the ailanthus silkmoth, the
wasps destroy a larger number of the female than of the male
caterpillars. Dr. Wallace further remarks that female caterpillars,
from being larger than the males, require more time for their
development, and consume more food and moisture: and thus they would
be exposed during a longer time to danger from ichneumons, birds, &c.,
and in times of scarcity would perish in greater numbers. Hence it
appears quite possible that in a state of nature, fewer female
Lepidoptera may reach maturity than males; and for our special
object we are concerned with their relative numbers at maturity,
when the sexes are ready to propagate their kind.
The manner in which the males of certain moths congregate in
extraordinary numbers round a single female, apparently indicates a
great excess of males, though this fact may perhaps be accounted for
by the earlier emergence of the males from their cocoons. Mr. Stainton
informs me that from twelve to twenty males, may often be seen
congregated round a female Elachista rufocinerea. It is well known
that if a virgin Lasiocampa quercus or Saturnia carpini be exposed
in a cage, vast numbers of males collect round her, and if confined in
a room will even come down the chimney to her. Mr. Doubleday
believes that he has seen from fifty to a hundred males of both
these species attracted in the course of a single day by a female in
confinement. In the Isle of Wight Mr. Trimen exposed a box in which
a female of the Lasiocampa had been confined on the previous day,
and five males soon endeavored to gain admittance. In Australia, Mr.
Verreaux, having placed the female of a small Bombyx in a box in his
pocket, was followed by a crowd of males, so that about 200 entered
the house with him.*
* Blanchard, Metamorphoses, Moeurs des Insectes, 1868, pp. 225-226.
Mr. Doubleday has called my attention to M. Staudinger's* list of
Lepidoptera, which gives the prices of the males and females of 300
species or well-marked varieties of butterflies (Rhopalocera). The
prices for both sexes of the very common species are of course the
same; but in 114 of the rarer species they differ; the males being
in all cases, excepting one, the cheaper. On an average of the
prices of the 113 species, the price of the male to that of the female
is as 100 to 149; and this apparently indicates that inversely the
males exceed the females in the same proportion. About 2000 species or
varieties of moths (Heterocera) are catalogued, those with wingless
females being here excluded on account of the difference in habits
between the two sexes: of these 2000 species, 141 differ in price
according to sex, the males of 130 being cheaper, and those of only 11
being dearer than the females. The average price of the males of the
130 species, to that of the females, is as 100 to 143. With respect to
the butterflies in this priced list, Mr. Doubleday thinks (and no
man in England has had more experience), that there is nothing in
the habits of the species which can account for the difference in
the prices of the two sexes, and that it can be accounted for only
by an excess in the number of the males. But I am bound to add that
Dr. Staudinger informs me, that he is himself of a different
opinion. He thinks that the less active habits of the females and
the earlier emergence of the males will account for his collectors
securing a larger number of males than of females, and consequently
for the lower prices of the former. With respect to specimens reared
from the caterpillar-state, Dr. Staudinger believes, as previously
stated, that a greater number of females than of males die whilst
confined to the cocoons. He adds that with certain species one sex
seems to preponderate over the other during certain years.
* Lepidopteren-Doubletten Liste, Berlin, No. x., 1866.
Of direct observations on the sexes of Lepidoptera, reared either
from eggs or caterpillars, I have received only the few following
cases:*
* See following table.
So that in these eight lots of cocoons and eggs, males were produced
in excess. Taken together the proportion of males is as 122.7 to 100
females. But the numbers are hardly large enough to be trustworthy.
On the whole, from these various sources of evidence, all pointing
in the same direction, I infer that with most species of
Lepidoptera, the mature males generally exceed the females in
number, whatever the proportions may be at their first emergence
from the egg.
Males Females
The Rev. J. Hellins* of Exeter reared, during
1868, imagos of 73 species, which
consisted of 153 137
Mr. Albert Jones of Eltham reared, during
1868, imagos of 9 species, which
consisted of 159 126
During 1869 he reared imagoes from 4 species
consisting of 114 112
Mr. Buckler of Emsworth, Hants, during 1869,
reared imagos from 74 species,
consisting of 180 169
Dr. Wallace of Colchester reared from one
brood of Bombyx cynthia 52 48
Dr. Wallace raised, from cocoons of Bombyx
pernyi sent from China, during 1869 224 123
Dr. Wallace raised, during 1868 and 1869, from
two lots of cocoons of Bombyx yamamai 52 46
Total 934 761
* This naturalist has been so kind as to send me some results from
former years, in which the females seemed to preponderate; but so many
of the figures were estimates, that I found it impossible to
tabulate them
With reference to the other orders of insects, I have been able to
collect very little reliable information. With the stag-beetle
(Lucanus cervus) "the males appear to be much more numerous than the
females"; but when, as Cornelius remarked during 1867, an unusal
number of these beetles appeared in one part of Germany, the females
appeared to exceed the males as six to one. With one of the
Elateridae, the males are said to be much more numerous than the
females, and "two or three are often found united with one female;* so
that here polyandry seems to prevail." With Siagonium (Staphylinidae),
in which the males are furnished with horns, "the females are far more
numerous than the opposite sex." Mr. Janson stated at the
Entomological Society that the females of the bark feeding Tomicus
villosus are so common as to be a plague, whilst the males are so rare
as to be hardly known.
* Gunther's Record of Zoological Literature, 1867, p. 260. On the
excess of female Lucanus, ibid, p. 250. On the males of Lucanus in
England, Westwood, Modern Classification of Insects, vol. i., p.
187. On the Siagonium, ibid., p. 172.
It is hardly worthwhile saying anything about the proportion of
the sexes in certain species and even groups of insects, for the males
are unknown or very rare, and the females are parthenogenetic, that
is, fertile without sexual union; examples of this are afforded by
several of the Cynipidae.* In all the gall-making Cynipidae known to
Mr. Walsh, the females are four or five times as numerous as the
males; and so it is, as he informs me, with the gall-making
Cecidomyiidae (Diptera). With some common species of saw-flies
(Tenthredinae) Mr. F. Smith has reared hundreds of specimens from
larvae of all sizes, but has never reared a single male; on the
other hand, Curtis says,*(2) that with certain species (Athalia), bred
by him, the males were to the females as six to one; whilst exactly
the reverse occurred with the mature insects of the same species
caught in the fields. In the family of bees, Hermann Muller,*(3)
collected a large number of specimens of many species, and reared
others from the cocoons, and counted the sexes. He found that the
males of some species greatly exceeded the females in number; in
others the reverse occurred; and in others the two sexes were nearly
equal. But as in most cases the males emerge from the cocoons before
the females, they are at the commencement of the breeding-season
practically in excess. Muller also observed that the relative number
of the two sexes in some species differed much in different
localities. But as H. Muller has himself remarked to me, these remarks
must be received with some caution, as one sex might more easily
escape observation than the other. Thus his brother Fritz Muller has
noticed in Brazil that the two sexes of the same species of bee
sometimes frequent different kinds of flowers. With respect to the
Orthoptera, I know hardly anything about the relative number of the
sexes: Korte,*(4) however, says that out of 500 locusts which he
examined, the males were to the females as five to six. With the
Neuroptera, Mr. Walsh states that in many, but by no means in all
the species of the odonatous group, there is a great overplus of
males: in the genus Hetaerina, also, the males are generally at
least four times as numerous as the females. In certain species in the
genus Gomphus the males are equally in excess, whilst in two other
species, the females the are twice or thrice as numerous as the males.
In some European species of Psocus thousands of females may be
collected without a single male, whilst with other species of the same
genus both sexes are common.*(5) In England, Mr. MacLachlan has
captured hundreds of the female Apatania muliebris, but has never seen
the male; and of Boreus hyemalis only four or five males have been
seen here.*(6) With most of these species (excepting the Tenthredinae)
there is at present no evidence that the females are subject to
parthenogenesis; and thus we see how ignorant we are of the causes
of the apparent discrepancy in the proportion of the two sexes.
* Walsh in the American Entomologist, vol. i., 1869, p. 103. F.
Smith, Record of Zoological Lit, 1867, p. 328.
*(2) Farm Insects, pp. 45-46.
*(3) "Anwendung der Darwin'schen Lehre," Verh. d. n. Jahrg., xxiv.
*(4) Die Strich. Zug oder Wanderheuschrecke, 1828, p. 20.
*(5) "Observations on N. American Neuroptera," by H. Hagen and B. D.
Walsh, Proceedings, Ent. Soc. Philadelphia, Oct., 1863, pp. 168,
223, 239.
*(6) Proceedings, Ent. Soc. London, Feb. 17, 1868.
In the other classes of the Articulata I have been able to collect
still less information. With spiders, Mr. Blackwall, who has carefully
attended to this class during many years, writes to me that the
males from their more erratic habits are more commonly seen, and
therefore appear more numerous. This is actually the case with a few
species; but he mentions several species in six genera, in which the
females appear to be much more numerous than the males.* The small
size of the males in comparison with the females (a peculiarity
which is sometimes carried to an extreme degree), and their widely
different appearance, may account in some instances for their rarity
in collections.*(2)
8888
* Another great authority with respect to this class, Prof.
Thorell of Upsala (On European Spiders, 1869-70, part i., p. 205),
speaks as if female spiders were generally commoner than the males.
*(2) See, on this subject, Mr. O. P. Cambridge, as quoted in
Quarterly Journal of Science, 1868, page 429.
Some of the lower crustaceans are able to propagate their kind
sexually, and this will account for the extreme rarity of the males;
thus von Siebold* carefully examined no less than 13,000 specimens
of Apus from twenty-one localities, and amongst these he found only
319 males. With some other forms (as Tanais and Cypris), as Fritz
Muller informs me, there is reason to believe that the males are
much shorter-lived than the females; and this would explain their
scarcity, supposing the two sexes to be at first equal in number. On
the other hand, Muller has invariably taken far more males than
females of the Diastylidae and of Cypridina on the shores of Brazil:
thus with a species in the latter genus, 63 specimens caught the
same day included 57 males; but he suggests that this preponderance
may be due to some unknown difference in the habits of the two
sexes. With one of the higher Brazilian crabs, namely a Gelasimus,
Fritz Muller found the males to be more numerous than the females.
According to the large experience of Mr. C. Spence Bate, the reverse
seems to be the case with six common British crabs, the names of which
he has given me.
* Beitrage zur Parthenogenesis, p. 174.
The proportion of the sexes in relation to natural selection.
There is reason to suspect that in some cases man has by
selection6 indirectly influenced his own sex-producing powers. Certain
women tend to produce during their whole lives more children of one
sex than of the other: and the same holds good of many animals, for
instance, cows and ho6rses; thus Mr. Wright of Yeldersley House
informs me that one of his Arab mares, though put seven times to
different horses, produced seven fillies. Though I have very little
evidence on this head, analogy would lead to the belief, that the
tendency to produce either sex would be inherited like almost every
other peculiarity, for instance, that of producing twins; and
concerning the above tendency a good authority, Mr. J. Downing, has
communicated to me facts which seem to prove that this does occur in
certain families of short-horn cattle. Col. Marshall* has recently
found on careful examination that the Todas, a hill-tribe of India,
consist of 112 males and 84 females of all ages- that is in a ratio of
133.3 males to 100 females. The Todas, who are polyandrous in their
marriages, during former times invariably practised female
infanticide; but this practice has now been discontinued for a
considerable period. Of the children born within late years, the males
are more numerous than the females, in the proportion of 124 to 100.
Colonel Marshall accounts for this fact in the following ingenious
manner. "Let us for the purpose of illustration take three families as
representing an average of the entire tribe; say that one mother gives
birth to six daughters and no sons; a second mother has six sons only,
whilst the third mother has three sons and three daughters. The
first mother, following the tribal custom, destroys four daughters and
preserves two. The second retains her six sons. The third kills two
daughters and keeps one, as also her three sons. We have then from the
three families, nine sons and three daughters, with which to
continue the breed. But whilst the males belong to families in which
the tendency to produce sons is great, the females are of those of a
converse inclination. Thus the bias strengthens with each
generation, until, as we find, families grow to have habitually more
sons than daughters."
* The Todas, 1873, pp. 100, 111, 194, 196.
That this result would follow from the above form of infanticide
seems almost certain; that is if we assume that a sex-producing
tendency is inherited. But as the above numbers are so extremely
scanty, I have searched for additional evidence, but cannot decide
whether what I have found is trustworthy; nevertheless the facts
are, perhaps, worth giving. The Maories of New Zealand have long
practised infanticide; and Mr. Fenton* states that he "has met with
instances of women who have destroyed four, six, and even seven
children, mostly females. However, the universal testimony of those
best qualified to judge, is conclusive that this custom has for many
years been almost extinct. Probably the year 1835 may be named as
the period of its ceasing to exist." Now amongst the New Zealanders,
as with the Todas, male births are considerably in excess. Mr.
Fenton remarks (p. 30), "One fact is certain, although the exact
period of the commencement of this singular condition of the
disproportion of the sexes cannot be demonstratively fixed, it is
quite clear that this course of decrease was in full operation
during the years 1830 to 1844, when the non-adult population of 1844
was being produced, and has continued with great energy up to the
present time." The following statements are taken from Mr. Fenton
(p. 26), but as the numbers are not large, and as the census was not
accurate, uniform results cannot be expected. It should be borne in
mind in this and the following cases, that the normal state of every
population is an excess of women, at least in all civilised countries,
chiefly owing to the greater mortality of the male sex during youth,
and partly to accidents of all kinds later in life. In 1858, the
native population of New Zealand was estimated as consisting of 31,667
males and 24,303 females of all ages, that is in the ratio of 130.3
males to 100 females. But during this same year, and in certain
limited districts, the numbers were ascertained with much care, and
the males of all ages were here 753 and the females 616; that is in
the ratio of 122.2 males to 100 females. It is more important for us
that during this same year of 1858, the non-adult males within the
same district were found to be 178, and the non-adult females 142,
that is in the ratio of 125.3 to 100. It may be added that in 1844, at
which period female infanticide had only lately ceased, the
non-adult males in one district were 281, and the non-adult females
only 194, that is in the ratio of 144.8 males to 100 females.
* Aboriginal Inhabitants of New Zealand (Government Report), 1859,
p. 36.
In the Sandwich Islands, the males exceed the females in number.
Infanticide was formerly practised there to a frightful extent, but
was by no means confined to female infants, as is shown by Mr. Ellis,*
and as I have been informed by Bishop Staley and the Rev. Mr. Coan.
Nevertheless, another apparently trustworthy writer, Mr. Jarves,*(2)
whose observations apply to the whole archipelago, remarks:-
"Numbers of women are to be found, who confess to the murder of from
three to six or eight children," and he adds, "females from being
considered less useful than males were more often destroyed." From
what is known to occur in other parts of the world, this statement
is probable; but must be received with much caution. The practice of
infanticide ceased about the year 1819, when idolatry was abolished
and missionaries settled in the islands. A careful census in 1839 of
the adult and taxable men and women in the island of Kauai and in
one district of Oahu (Jarves, p. 404), gives 4723 males and 3776
females; that is in the ratio of 125.08 to 100. At the same time the
number of males under fourteen years in Kauai and under eighteen in
Oahu was 1797, and of females of the same ages 1429; and here we
have the ratio of 125.75 males to 100 females.
* Narrative of a Tour through Hawaii, 1826, p. 298.
*(2) History of the Sandwich Islands, 1843, p. 93.
In a census of all the islands in 1850,* the males of all ages
amount to 36,272, and the females to 33,128, or as 109.49 to 100.
The males under seventeen years amounted to 10,773, and the females
under the same age to 9593, or as 112.3 to 100. From the census of
1872, the proportion of males of all ages (including half-castes) to
females, is as 125.36 to 100. It must be borne in mind that all
these returns for the Sandwich Islands give the proportion of living
males to living females, and not of the births; and judging from all
civilised countries the proportion of males would have been
considerably higher if the numbers had referred to births.*(2)
* This is given in the Rev. H. T. Cheever's Life in the Sandwich
Islands, 1851, p. 277.
*(2) Dr. Coulter, in describing (Journal R. Geograph. Soc., vol. v.,
1835, p. 67) the state of California about the year 1830, says that
the natives reclaimed by the Spanish missionaries, have nearly all
perished, or are perishing, although well treated, not driven from
their native land, and kept from the use of spirits. He attributes
this, in great part, to the undoubted fact that the men greatly exceed
the women in number; but he does not know whether this is due to a
failure of female offspring, or to more females dying during early
youth. The latter alternative, according to all analogy, is very
improbable. He adds that "infanticide, properly so called, is not
common, though very frequent recourse is had to abortion." If Dr.
Coulter is correct about infanticide, this case cannot be advanced
in support of Colonel Marshall's view. From the rapid decrease of
the reclaimed natives, we may suspect that, as in the cases lately
given, their fertility has been diminished from changed habits of
life.
I had hoped to gain some light on this subject from the breeding
of dogs; inasmuch as most breeds, with the exception, perhaps, of
greyhounds, many more female puppies are destroyed than males, just as
with the Toda infants. Mr. Cupples assures me that this is usual
with Scotch deerhounds. Unfortunately, I know nothing of the
proportion of the sexes in any breed, excepting greyhounds, and
there the male births are to the females as 110.1 to 100. Now from
enquiries made from many breeders, it seems that the females are in
some respects more esteemed, though otherwise troublesome; and it does
not appear that the female puppies of the best-bred dogs are
systematically destroyed more than the males, though this does
sometimes take place to a limited extent. Therefore I am unable to
decide whether we can, on the above principles, account for the
preponderance of male births in greyhounds. On the other hand, we have
seen that with horses, cattle, and sheep, which are too valuable for
the young of either sex to be destroyed, if there is any difference,
the females are slightly in excess.
From the several foregoing cases we have some reason to believe that
infanticide practised in the manner above explained, tends to make a
male-producing race; but I am far from supposing that this practice in
the case of man, or some analogous process with other species, has
been the sole determining cause of an excess of males. There may be
some unknown law leading to this result in decreasing races, which
have already become somewhat infertile. Besides the several causes
previously alluded to, the greater facility of parturition amongst
savages, and the less consequent injury to their male infants, would
tend to increase the proportion of live-born males to females. There
does not, however, seem to be any necessary connection between
savage life and a marked excess of males; that is if we may judge by
the character of the scanty offspring of the lately existing
Tasmanians and of the crossed offspring of the Tahitians now
inhabiting Norfolk Island.
As the males and females of many animals differ somewhat in habits
and are exposed in different degrees to danger, it is probable that in
many cases, more of one sex than of the other are habitually
destroyed. But as far as I can trace out the complication of causes,
an indiscriminate though large destruction of either sex would not
tend to modify the sex-producing power of the species. With strictly
social animals, such as bees or ants, which produce a vast number of
sterile and fertile females in comparison with the males, and to
whom this preponderance is of paramount importance, we can see that
those communities would flourish best which contained females having a
strong inherited tendency to produce more and more females; and in
such cases an unequal sex-producing tendency would be ultimately
gained through natural selection. With animals living in herds or
troops, in which the males come to the front and defend the herd, as
with the bisons of North America and certain baboons, it is
conceivable that a male-producing tendency might be gained by
natural selection; for the individuals of the better defended herds
would leave more numerous descendants. In the case of mankind the
advantage arising from having a preponderance of men in the tribe is
supposed to be one chief cause of the practice of female infanticide.
In no case, as far as we can see, would an inherited tendency to
produce both sexes in equal numbers or to produce one sex in excess,
be a direct advantage or disadvantage to certain individuals more than
to others; for instance, an individual with a tendency to produce more
males than females would not succeed better in the battle for life
than an individual with an opposite tendency; and therefore a tendency
of this kind could not be gained through natural selection.
Nevertheless, there are certain animals (for instance, fishes and
cirripedes) in which two or more males appear to be necessary for
the fertilisation of the female; and the males accordingly largely
preponderate, but it is by no means obvious how this male-producing
tendency could have been acquired. I formerly thought that when a
tendency to produce the two sexes in equal numbers was advantageous to
the species, it would follow from natural selection, but I now see
that the whole problem is so intricate that it is safer to leave its
solution for the future.
CHAPTER IX.
SECONDARY SEXUAL CHARACTERS IN THE LOWER CLASSES
OF THE ANIMAL KINGDOM.
WITH animals belonging to the lower classes, the two sexes are not
rarely united in the same individual, and therefore secondary sexual
characters cannot be developed. In many cases where the sexes are
separate, both are permanently attached to some support, and the one
cannot search or struggle for the other. Moreover it is almost certain
that these animals have too imperfect senses and much too low mental
powers to appreciate each other's beauty or other attractions, or to
feel rivalry.
Hence in these classes or sub-kingdoms, such as the Protozoa,
Coelenterata, Echinodermata, Scolecida, secondary sexual characters,
of the kind which we have to consider, do not occur: and this fact
agrees with the belief that such characters in the higher classes have
been acquired through sexual selection, which depends on the will,
desire, and choice of either sex. Nevertheless some few apparent
exceptions occur; thus, as I hear from Dr. Baird, the males of certain
Entozoa, or internal parasitic worms, differ slightly in colour from
the females; but we have no reason to suppose that such differences
have been augmented through sexual selection. Contrivances by which
the male holds the female, and which are indispensable for the
propagation of the species, are independent of sexual selection, and
have been acquired through ordinary selection.
Many of the lower animals, whether hermaphrodites or with separate
sexes, are ornamented with the most brilliant tints, or are shaded and
striped in an elegant manner; for instance, many corals and
sea-anemones (Actiniae), some jelly-fish (Medusae, Porpita, &c.), some
Planariae, many star-fishes, Echini, ascidians, &c.; but we may
conclude from the reasons already indicated, namely, the union of
the two sexes in some of these animals, the permanently affixed
condition of others, and the low mental powers of all, that such
colours do not serve as a sexual attraction, and have not been
acquired through sexual selection. It should be borne in mind that
in no case have we sufficient evidence that colours have been thus
acquired, except where one sex is much more brilliantly or
conspicuously coloured than the other, and where there is no
difference in habits between the sexes sufficient to account for their
different colours. But the evidence is rendered as complete as it
can ever be, only when the more ornamented individuals, almost
always the males, voluntarily display their attractions before the
other sex; for we cannot believe that such display is useless, and
if it be advantageous, sexual selection will almost inevitably follow.
We may, however, extend this conclusion to both sexes, when coloured
alike, if their colours are plainly analogous to those of one sex
alone in certain other species of the same group.
How, then, are we to account for the beautiful or even gorgeous
colours of many animals in the lowest classes? It appears doubtful
whether such colours often serve as a protection; but that we may
easily err on this head, will be admitted by every one who reads Mr.
Wallace's excellent essay on this subject. It would not, for instance,
at first occur to any one that the transparency of the Medusae, or
jelly-fish, is of the highest service to them as a protection; but
when we are reminded by Haeckel that not only the Medusae, but many
floating Mollusca, crustaceans, and even small oceanic fishes
partake of this same glass-like appearance, often accompanied by
prismatic colours, we can hardly doubt that they thus escape the
notice of pelagis birds and other enemies. M. Giard is also convinced*
that the bright tints of certain sponges and ascidians serve as a
protection. Conspicuous colours are likewise beneficial to many
animals as a warning to their would-be devourers that they are
distasteful, or that they possess some special means of defence; but
this subject will be discussed more conveniently hereafter.
* Archives de Zoolog. Exper., Oct., 1872, p. 563.
We can, in our ignorance of most of the lowest animals, only say
that their bright tints result either from the chemical nature or
the minute structure of their tissues, independently of any benefit
thus derived. Hardly any colour is finer than that of arterial
blood; but there is no reason to suppose that the colour of the
blood is in itself any advantage; and though it adds to the beauty
of the maiden's cheek, no one will pretend that it has been acquired
for this purpose. So again with many animals, especially the lower
ones, the bile is richly coloured; thus, as I am informed by Mr.
Hancock, the extreme beauty of the Eolidae (naked sea-slugs) is
chiefly due to the biliary glands being seen through the translucent
integuments- this beauty being probably of no service to these
animals. The tints of the decaying leaves in an American forest are
described by every one as gorgeous; yet no one supposes that these
tints are of the least advantage to the trees. Bearing in mind how
many substances closely analogous to natural organic compounds have
been recently formed by chemists, and which exhibit the most
splendid colours, it would have been a strange fact if substances
similarly coloured had not often originated, independently of any
useful end thus gained, in the complex laboratory of living organisms.
The sub-kingdom of the MOLLUSCA.- Throughout this great division
of the animal kingdom, as far as I can discover, secondary sexual
characters, such as we are here considering, never occur. Nor could
they be expected in the three lowest classes, namely, in the
ascidians, Polyzoa, and brachiopods (constituting the Molluscoida of
some authors), for most of these animals are permanently affixed to
a support or have their sexes united in the same individual. In the
Lamellibranchiata, or bivalve shells, hermaphroditism is not rare.
In the next higher classes of the Gasteropoda, or univalve shells, the
sexes are either united or separate. But in the latter case the
males never possess special organs for finding, securing, or
charming the females, or for fighting with other males. As I am
informed by Mr. Gwyn Jeffreys, the sole external difference between
the sexes consists in the shell sometimes differing a little in
form; for instance, the shell of the male periwinkle (Littorina
littorea) is narrower and has a more elongated spire than that of
the female. But differences of this nature, it may be presumed, are
directly connected with the act of reproduction, or with the
development of the ova.
The Gasteropoda, though capable of locomotion and furnished with
imperfect eyes, do not appear to be endowed with sufficient mental
powers for the members of the same sex to struggle together in
rivalry, and thus to acquire secondary sexual characters. Nevertheless
with the pulmoniferous gasteropods, or land-snails, the pairing is
preceded by courtship; for these animals, though hermaphrodites, are
compelled by their structure to pair together. Agassiz remarks,
"Quiconque a eu l'occasion d'observer les amours des limacons, ne
saurait mettre en doute la seduction deployee dans les mouvements et
les allures qui preparent et accomplissent le double embrassement de
ces hermaphrodites."* These animals appear also susceptible of some
degree of permanent attachment: an accurate observer, Mr. Lonsdale,
informs me that he placed a pair of land-snails (Helix pomatia), one
of which was weakly, into a small and ill-provided garden. After a
short time the strong and healthy individual disappeared, and was
traced by its track of slime over a wall into an adjoining
well-stocked garden. Mr. Lonsdale concluded that it had deserted its
sickly mate; but after an absence of twenty-four hours it returned,
and apparently communicated the result of its successful
exploration, for both then started along the same track and
disappeared over the wall.
* De l'Espece et de la Class. &c., 1869, p. 106.
Even in the highest class of the Mollusca, the Cephalopoda or
cuttle-fishes, in which the sexes are separate, secondary sexual
characters of the present kind do not, as far as I can discover,
occur. This is a surprising circumstance, as these animals possess
highly-developed sense-organs and have considerable mental powers,
as will be admitted by every one who has watched their artful
endeavours to escape from an enemy.* Certain Cephalopoda, however, are
characterised by one extraordinary sexual character, namely that the
male element collects within one of the arms or tentacles, which is
then cast off, and clinging by its sucking-discs to the female,
lives for a time an independent life. So completely does the
cast-off arm resemble a separate animal, that it was described by
Cuvier as a parasitic worm under the name of Hectocotyle. But this
marvellous structure may be classed as a primary rather than as a
secondary sexual character.
* See, for instance, the account which I have given in my Journal of
Researches, 1845, p. 7.
Although with the Mollusca sexual selection does not seem to have
come into play; yet many univalve and bivalve shells, such as volutes,
cones, scallops, &c., are beautifully coloured and shaped. The colours
do not appear in most cases to be of any use as a protection; they are
probably the direct result, as in the lowest classes, of the nature of
the tissues; the patterns and the sculpture of the shell depending
on its manner of growth. The amount of light seems to be influential
to a certain extent; for although, as repeatedly stated by Mr. Gwyn
Jeffreys, the shells of some species living at a profound depth are
brightly coloured, yet we generally see the lower surfaces, as well as
the parts covered by the mantle, less highly-coloured than the upper
and exposed surfaces.* In some cases, as with shells living amongst
corals or brightly-tinted seaweeds, the bright colours may serve as
a protection.*(2) But that many of the nudibranch Mollusca, or
sea-slugs, are as beautifully coloured as any shells, may be seen in
Messrs. Alder and Hancock's magnificent work; and from information
kindly given me by Mr. Hancock, it seems extremely doubtful whether
these colours usually serve as a protection. With some species this
may be the case, as with one kind which lives on the green leaves of
algae, and is itself bright-green. But many brightly-coloured,
white, or otherwise conspicuous species, do not seek concealment;
whilst again some equally conspicuous species, as well as other
dull-coloured kinds live under stones and in dark recesses. So that
with these nudibranch molluscs, colour apparently does not stand in
any close relation to the nature of the places which they inhabit.
* I have given (Geological Observations on Volcanic Islands, 1844,
p. 53) a curious instance of the influence of light on the colours
of a frondescent incrustation, deposited by the surf on the
coast-rocks of Ascension and formed by the solution of triturated
sea-shells.
*(2) Dr. Morse has lately discussed this subject in his paper on the
"Adaptive Coloration of Mollusca," Proc. Boston Soc. of Nat. Hist.,
vol. xiv., April, 1871.
These naked sea-slugs are hermaphrodites, yet they pair together, as
do land-snails, many of which have extremely pretty shells. It is
conceivable that two hermaphrodites, attracted by each other's greater
beauty, might unite and leave offspring which would inherit their
parents' greater beauty. But with such lowly-organised creatures
this is extremely improbable. Nor is it at all obvious how the
offspring from the more beautiful pairs of hermaphrodites would have
any advantage over the offspring of the less beautiful, so as to
increase in number, unless indeed vigour and beauty generally
coincided. We have not here the case of a number of males becoming
mature before the females, with the more beautiful males selected by
the more vigorous females. If, indeed, brilliant colours were
beneficial to a hermaphrodite animal in relation to its general habits
of life, the more brightly-tinted individuals would succeed best and
would increase in number; but this would be a case of natural and
not of sexual selection.
Sub-kingdom of the VERMES; Class: ANNELIDA (or Sea-worms).- In
this class, although the sexes, when separate, sometimes differ from
each other in characters of such importance that they have been placed
under distinct genera or even families, yet the differences do not
seem of the kind which can be safely attributed to sexual selection.
These animals are often beautifully coloured, but as the sexes do
not differ in this respect, we are but little concerned with them.
Even the nemertians, though so lowly organised, "vie in beauty and
variety of colouring with any other group in the invertebrate series";
yet Dr. McIntosh* cannot discover that these colours are of any
service. The sedentary annelids become duller-coloured, according to
M. Quatrefages,*(2) after the period of reproduction; and this I
presume may be attributed to their less vigorous condition at that
time. All these worm-like animals apparently stand too low in the
scale for the individuals of either sex to exert any choice in
selecting a partner, or for the individuals of the same sex to
struggle together in rivalry.
* See his beautiful monograph on British Annelids, part i., 1873, p.
3.
*(2) See M. Perrier: "L'Origine de l'Homme d'apres Darwin," Revue
Scientifique, Feb., 1873, p. 866.
Sub-kingdom of the ARTHROPODA; Class: CRUSTACEA.- In this great
class we first meet with undoubted secondary sexual characters,
often developed in a remarkable manner. Unfortunately the habits of
crustaceans are very imperfectly known, and we cannot explain the uses
of many structures peculiar to one sex. With the lower parasitic
species the males are of small size, and they alone are furnished with
perfect swimming-legs, antennae and sense-organs; the females being
destitute of these organs, with their bodies often consisting of a
mere distorted mass. But these extraordinary differences between the
two sexes are no doubt related to their widely different habits of
life, and consequently do not concern us. In various crustaceans,
belonging to distinct families, the anterior antennae are furnished
with peculiar thread-like bodies, which are believed to act as
smelling-organs, and these are much more numerous in the males than in
the females. As the males, without any unusual development of their
olfactory organs, would almost certainly be able sooner or later to
find the females, the increased number of the smelling-threads has
probably been acquired through sexual selection, by the better
provided males having been the more successful in finding partners and
in producing offspring. Fritz Muller has described a remarkable
dimorphic species of Tanais, in which the male is represented by two
distinct forms, which never graduate into each other. In the one
form the male is furnished with more numerous smelling-threads, and in
the other form with more powerful and more elongated chelae or
pincers, which serve to hold the female. Fritz Muller suggests that
these differences between the two male forms of the same species may
have originated in certain individuals having varied in the number
of the smelling-threads, whilst other individuals varied in the
shape and size of their chelae; so that of the former, those which
were best able to find the female, and of the latter, those which were
best able to hold her, have left the greatest number of progeny to
inherit their respective advantages.*
* Facts and arguments for Darwin, English translat., 1869, p. 20.
See the previous discussion on the olfactory threads. Sars has
described a somewhat analogous case (as quoted in Nature, 1870, p.
455) in a Norwegian crustacean, the Pontoporeia affinis.
In some of the lower crustaceans, the right anterior antenna of
the male differs greatly in structure from the left, the latter
resembling in its simple tapering joints the antennae of the female.
In the male the modified antenna is either swollen in the middle or
angularly bent, or converted (see fig. 4) into an elegant, and
sometimes wonderfully complex, prehensile organ.* It serves, as I hear
from Sir J. Lubbock, to hold the female, and for this same purpose one
of the two posterior legs (b) on the same side of the body is
converted into a forceps. In another family the inferior or
posterior antennae are "curiously zigzagged" in the males alone.
* See Sir J. Lubbock in Annals and Mag. of Nat. Hist., vol. xi.,
1853, pls. i. and x.; and vol. xii. (1853), pl. vii. See also
Lubbock in Transactions, Entomological Society, vol. iv., new
series, 1856-1858, p. 8. With respect to the zigzagged antennae
mentioned below, see Fritz Muller, Facts and Arguments for Darwin,
1869, p. 40, footnote.
In the higher crustaceans the anterior legs are developed into
chelae or pincers; and these are generally larger in the male than
in the female,- so much so that the market value of the male edible
crab (Cancer pagurus), according to Mr. C. Spence Bate, is five
times as great as that of the female. In many species the chelae are
of unequal size on the opposite side of the body, the right-hand one
being, as I am informed by Mr. Bate, generally, though not invariably,
the largest. This inequality is also often much greater in the male
than in the female. The two chelae of the male often differ in
structure (see figs. 5, 6, and 7), the smaller one resembling that
of the female. What advantage is gained by their inequality in size on
the opposite sides of the body, and by the inequality being much
greater in the male than in the female; and why, when they are of
equal size, both are often much larger in the male than in the female,
is not known. As I hear from Mr. Bate, the chelae are sometimes of
such length and size that they cannot possibly be used for carrying
food to the mouth. In the males of certain fresh-water prawns
(Palaemon) the right leg is actually longer than the whole body.*
The great size of the one leg with its chelae may aid the male in
fighting with his rivals; but this will not account for their
inequality in the female on the opposite sides of the body. In
Gelasimus, according to a statement quoted by Milne Edwards,*(2) the
male and the female live in the same burrow, and this shews that
they pair; the male closes the mouth of the burrow with one of its
chelae, which is enormously developed; so that here it indirectly
serves as a means of defence. Their main use, however, is probably
to seize and to secure the female, and this in some instances, as with
Gammarus, is known to be the case. The male of the hermit or soldier
crab (Pagurus) for weeks together, carries about the shell inhabited
by the female.*(3) The sexes, however, of the common shore-crab
(Carcinus manas), as Mr. Bate informs me, unite directly after the
female has moulted her hard shell, when she is so soft that she
would be injured if seized by the strong pincers of the male; but as
she is caught and carried about by the male before moulting, she could
then be seized with impunity.
* See a paper by Mr. C. Spence Bate, with figures, in Proceedings,
Zoological Society, 1868, p. 363; and on the nomenclature of the
genus, ibid., p. 585. I am greatly indebted to Mr. Spence Bate for
nearly all the above statements with respect to the chelae of the
higher crustaceans.
*(2) Hist. Nat. des Crust., tom. ii., 1837, p. 50.
*(3) Mr. C. Spence Bate, British Association, Fourth Report on the
Fauna of S. Devon.
Fritz Muller states that certain species of Melita are distinguished
from all other amphipods by the females having "the coxal lemellae
of the penultimate pair of feet produced into hook-like processes,
of which the males lay hold with the hands of the first pair." The
development of these hook-like processes has probably followed from
those females which were the most securely held during the act of
reproduction, having left the largest number of offspring. Another
Brazilian amphipod (see Orchestia darwinii, fig. 8) presents a case of
dimorphism, like that of Tanais; for there are two male forms, which
differ in the structure of their chelae.* As either chela would
certainly suffice to hold the female,- for both are now used for
this purpose,- the two male forms probably originated by some having
varied in one manner and some in another; both forms having derived
certain special, but nearly equal advantages, from their differently
shaped organs.
* Fritz Muller, Facts and Arguments for Darwin, 1869, pp. 25-28.
It is not known that male crustaceans fight together for the
possession of the females, but it is probably the case; for with
most animals when the male is larger than the female, he seems to
owe his greater size to his ancestors having fought with other males
during many generations. In most of the orders, especially in the
highest or the Brachyura, the male is larger than the female; the
parasitic genera, however, in which the sexes follow different
habits of life, and most of the Entomostraca must be excepted. The
chelae of many crustaceans are weapons well adapted for fighting. Thus
when a devil-crab (Portunus puber) was seen by a son of Mr. Bate
fighting with a Carcinus maenas, the latter was soon thrown on its
back, and had every limb torn from its body. When several males of a
Brazilian Gelasimus, a species furnished with immense pincers, were
placed together in a glass vessel by Fritz Muller, they mutilated
and killed one another. Mr. Bate put a large male Carcinus maenas into
a pan of water, inhabited by a female which was paired with a
smaller male; but the latter was soon dispossessed. Mr. Bate adds, "if
they fought, the victory was a bloodless one, for I saw no wounds."
This same naturalist separated a male sand-skipper (so common on our
sea-shores), Gammarus marinus, from its female, both of whom were
imprisoned in the same vessel with many individuals of the same
species. The female, when thus divorced, soon joined the others. After
a time the male was put again into the same vessel; and he then, after
swimming about for a time, dashed into the crowd, and without any
fighting at once took away his wife. This fact shews that in the
Amphipoda, an order low in the scale, the males and females
recognise each other, and are mutually attached.
The mental powers of the Crustacea are probably higher than at first
sight appears probable. Any one who tries to catch one of the
shore-crabs, so common on tropical coasts, will perceive how wary
and alert they are. There is a large crab (Birgus latro), found on
coral islands, which makes a thick bed of the picked fibres of the
cocoa-nut, at the bottom of a deep burrow. It feeds on the fallen
fruit of this tree by tearing off the husk, fibre by fibre; and it
always begins at that end where the three eye-like depressions are
situated. It then breaks through one of these eyes by hammering with
its heavy front pincers, and turning round, extracts the albuminous
core with its narrow posterior pincers. But these actions are probably
instinctive, so that they would be performed as well by a young animal
as by an old one. The following case, however, can hardly be so
considered: a trustworthy naturalist, Mr. Gardner,* whilst watching
a shore-crab (Gelasimus) making its burrow, threw some shells
towards the hole. One rolled in, and three other shells remained
within a few inches of the mouth. In about five minutes the crab
brought out the shell which had fallen in, and carried it away to a
distance of a foot; it then saw the three other shells lying near, and
evidently thinking that they might likewise roll in, carried them to
the spot where it had laid the first. It would, I think, be
difficult to distinguish this act from one performed by man by the aid
of reason.
* Travels in the Interior of Brazil, 1846, p. 111. I have given,
in my Journal of Researches, p. 463, an account of the habits of the
Birgus.
Mr. Bate does not know of any well-marked case of difference of
colour in the two sexes of our British crustaceans, in which respect
the sexes of the higher animals so often differ. In some cases,
however, the males and females differ slightly in tint, but Mr. Bate
thinks not more than may be accounted for by their different habits of
life, such as by the male wandering more about, and being thus more
exposed to the light. Dr. Power tried to distinguish by colour the
sexes of the several species which inhabit Mauritius, but failed,
except with one species of Squilla, probably S. stylifera, the male of
which is described as being "of a beautiful bluish-green," with some
of the appendages cherry-red, whilst the female is clouded with
brown and grey, "with the red about her much less vivid than in the
male."* In this case, we may suspect the agency of sexual selection.
From M. Bert's observations on Daphnia, when placed in a vessel
illuminated by a prism, we have reason to believe that even the lowest
crustaceans can distinguish colours. With Saphirina (an oceanic
genus of Entomostraca), the males are furnished with minute shields or
cell-like bodies, which exhibit beautiful changing colours; these
are absent in the females, and in both sexes of one species.*(2) It
would, however, be extremely rash to conclude that these curious
organs serve to attract the females. I am informed by Fritz Muller,
that in the female of a Brazilian species of Gelasimus, the whole body
is of a nearly uniform greyish-brown. In the male the posterior part
of the cephalo-thorax is pure white, with the anterior part of a
rich green, shading into dark brown; and it is remarkable that these
colours are liable to change in the course of a few minutes- the white
becoming dirty grey or even black, the green "losing much of its
brilliancy." It deserves especial notice that the males do not acquire
their bright colours until they become mature. They appear to be
much more numerous than the females; they differ also in the larger
size of their chelae. In some species of the genus, probably in all,
the sexes pair and inhabit the same burrow. They are also, as we
have seen, highly intelligent animals. From these various
considerations it seems probable that the male in this species has
become gaily ornamented in order to attract or excite the female.
* Mr. Ch. Fraser, in Proc. Zoolog. Soc., 1869, p. 3.
*(2) Claus, Die freilebenden Copepoden, 1863, s. 35.
It has just been stated that the male Gelasimus does not acquire his
conspicuous colours until mature and nearly ready to breed. This seems
a general rule in the whole class in respect to the many remarkable
structural differences between the sexes. We shall hereafter find
the same law prevailing throughout the great sub-kingdom of the
Vertebrata; and in all cases it is eminently distinctive of characters
which have been acquired through sexual selection. Fritz Muller* gives
some striking instances of this law; thus the male sand-hopper
(Orchestia) does not, until nearly full grown, acquire his large
claspers, which are very differently constructed from those of the
female; whilst young, his claspers resemble those of the female.
* Facts and Arguments, &c., p. 79.
I am indebted to Mr. Bate for Dr. Power's statement.
Class: ARACHNIDA (Spiders).- The sexes do not generally differ
much in colour, but the males are often darker than the females, as
may be seen in Mr. Blackwall's magnificent work.* In some species,
however, the difference is conspicuous: thus the female of Sparassus
smaragdulus is dullish green, whilst the adult male has the abdomen of
a fine yellow, with three longitudinal stripes of rich red. In certain
species of Thomisus the sexes closely resemble each other, in others
they differ much; and analogous cases occur in many other genera. It
is often difficult to say which of the two sexes departs most from the
ordinary coloration of the genus to which the species belong; but
Mr. Blackwall thinks that, as a general rule, it is the male; and
Canestrini*(2) remarks that in certain genera the males can be
specifically distinguished with ease, but the females with great
difficulty. I am informed by Mr. Blackwall that the sexes whilst young
usually resemble each other; and both often undergo great changes in
colour during their successive moults, before arriving at maturity. In
other cases the male alone appears to change colour. Thus the male
of the above bright-coloured Sparassus at first resembles the
female, and acquires his peculiar tints only when nearly adult.
Spiders are possessed of acute senses, and exhibit much
intelligence; as is well known, the females often shew the strongest
affection for their eggs, which they carry about enveloped in a silken
web. The males search eagerly for the females, and have been seen by
Canestrini and others to fight for possession of them. This same
author says that the union of the two sexes has been observed in about
twenty species; and he asserts positively that the female rejects some
of the males who court her, threatens them with open mandibles, and at
last after long hesitation accepts the chosen one. From these
several considerations, we may admit with some confidence that the
well-marked differences in colour between the sexes of certain species
are the results of sexual selection; though we have not here the
best kind of evidence,- the display by the male of his ornaments. From
the extreme variability of colour in the male of some species, for
instance of Theridion lineatum, it would appear that these sexual
characters of the males have not as yet become well fixed.
Canestrini draws the same conclusion from the fact that the males of
certain species present two forms, differing from each other in the
size and length of their jaws; and this reminds us of the above
cases of dimorphic crustaceans.
* A History of the Spiders of Great Britain, 1861-64. For the
following facts, see pp. 77, 88, 102.
*(2) This author has recently published a valuable essay on the
"Caratteri sessuali secondarii degli Arachnidi," in the Atti della
Soc. Veneto-Trentina di Sc. Nat. Padova, vol. i., fasc. 3, 1873.
The male is generally much smaller than the female, sometimes to
an extraordinary degree,* and he is forced to be extremely cautious in
making his advances, as the female often carries her coyness to a
dangerous pitch. De Greer saw a male that "in the midst of his
preparatory caresses was seized by the object of his attentions,
enveloped by her in a web and then devoured, a sight which, as he
adds, filled him with horror and indignation."*(2) The Rev. O. P.
Cambridge*(3) accounts in the following manner for the extreme
smallness of the male in the genus Nephila. "M. Vinson gives a graphic
account of the agile way in which the diminutive male escapes from the
ferocity of the female, by gliding about and playing hide and seek
over her body and along her gigantic limbs: in such a pursuit it is
evident that the chances of escape would be in favour of the
smallest males, whilst the larger ones would fall early victims;
thus gradually a diminutive race of males would be selected, until
at last they would dwindle to the smallest possible size compatible
with the exercise of their generative functions,- in fact, probably to
the size we now see them, i. e., so small as to be a sort of
parasite upon the female, and either beneath her notice, or too
agile and too small for her to catch without great difficulty."
* Aug. Vinson (Araneides des Iles de la Reunion, pl. vi., figs. 1
and 2) gives a good instance of the small size of the male in Epeira
nigra. In this species, as I may add, the male is testaceous and the
female black with legs banded with red. Other even more striking cases
of inequality in size between the sexes have been recorded
(Quarterly Journal of Science, July, 1868, p. 429); but I have not
seen the original accounts.
*(2) Kirby and Spence, Introduction to Entomology, vol. i., 1818, p.
280.
*(3) Proceedings, Zoological Society, 1871, p. 621.
Westring has made the interesting discovery that the males of
several species of Theridion* have the power of making a
stridulating sound, whilst the females are mute. The apparatus
consists of a serrated ridge at the base of the abdomen, against which
the hard hinder part of the thorax is rubbed; and of this structure
not a trace can be detected in the females. It deserves notice that
several writers, including the well-known arachnologist Walckenaer,
have declared that spiders are attracted by music.*(2) From the
analogy of the Orthoptera and Homoptera, to be described in the next
chapter, we may feel almost sure that the stridulation serves, as
Westring also believes, to call or to excite the female; and this is
the first case known to me in the ascending scale of the animal
kingdom of sounds emitted for this purpose.*(3)
* Theridion (Asagena, Sund.) serratipes, 4-punctatum et guttatum;
see Westring, in Kroyer, Naturhist. Tidskrift, vol. iv., 1842-1843, p.
349; and vol. ii., 1846-1849, p. 342. See, also, for other species,
Araneae Suecicae, p. 184.
*(2) Dr. H. H. van Zouteveen, in his Dutch translation of this
work (vol. i., p. 444), has collected several cases.
*(3) Hilgendorf, however, has lately called attention to an
analogous structure in some of the higher crustaceans, which seems
adapted to produce sound; see Zoological Record, 1869, p. 603.
Class: MYRIAPODA.- In neither of the two orders in this class, the
millipedes and centipedes, can I find any well-marked instances of
such sexual differences as more particularly concern us. In Glomeris
limbata, however, and perhaps in some few other species, the males
differ slightly in colour from the females; but this Glomeris is a
highly variable species. In the males of the Diplopoda, the legs
belonging either to one of the anterior or of the posterior segments
of the body are modified into prehensile hooks which serve to secure
the female. In some species of Iulus the tarsi of the male are
furnished with membraneous suckers for the same purpose. As we shall
see when we treat of insects, it is a much more unusual
circumstance, that it is the female in Lithobius, which is furnished
with prehensile appendages at the extremity of her body for holding
the male.*
* Walckenaer et P. Gervais, Hist. Nat. des Insectes: Apteres, tom.
iv., 1847, pp. 17, 19, 68.
CHAPTER X.
SECONDARY SEXUAL CHARACTERS OF INSECTS.
IN the immense class of insects the sexes sometimes differ in
their locomotive-organs, and often in their sense-organs, as in the
pectinated and beautifully plumose antennae of the males of many
species. In Chloeon, one of the Ephemerae, the male has great pillared
eyes, of which the female is entirely destitute.* The ocelli are
absent in the females of certain insects, as in the Multillidae; and
here the females are likewise wingless. But we are chiefly concerned
with structures by which one male is enabled to conquer another,
either in battle or courtship, through his strength, pugnacity,
ornaments, or music. The innumerable contrivances, therefore, by which
the male is able to seize the female, may be briefly passed over.
Besides the complex structures at the apex of the abdomen, which ought
perhaps to be ranked as primary organs,*(2) "it is astonishing," as
Mr. B. D. Walsh*(3) has remarked, "how many different organs are
worked in by nature for the seemingly insignificant object of enabling
the male to grasp the female firmly." The mandibles or jaws are
sometimes used for this purpose; thus the male Corydalis cornutus (a
neuropterous insect in some degree allied to the dragon flies, &c.)
has immense curved jaws, many times longer than those of the female;
and they are smooth instead of being toothed, so that he is thus
enabled to seize her without injury.*(4) One of the stag-beetles of
North America (Lucanus elaphus) uses his jaws, which are much larger
than those of the female, for the same purpose, but probably
likewise for fighting. In one of the sand-wasps (Ammophila) the jaws
in the two sexes are closely alike, but are used for widely
different purposes: the males, as Professor Westwood observes, "are
exceedingly ardent, seizing their partners round the neck with their
sickle-shaped jaws";*(5) whilst the females use these organs for
burrowing in sand-banks and making their nests.
* Sir J. Lubbock, Transact. Linnean Soc., vol. xxv, 1866, p. 484.
With respect to the Mutillidae, see Westwood, Modern Class. of
Insects, vol. ii., p. 213.
*(2) These organs in the male often differ in closely-allied
species, and afford excellent specific characters. But their
importance, from a functional point of view, as Mr. R. MacLachlan
has remarked to me, has probably been overrated. It has been
suggested, that slight differences in these organs would suffice to
prevent the intercrossing of well-marked varieties or incipient
species, and would thus aid in their development. That this can hardly
be the case, we may infer from the many recorded cases (see, for
instance, Bronn, Geschichte der Natur, B. ii., 1843, s. 164; and
Westwood, Transact. Ent. Soc., vol. iii., 1842, p. 195) of distinct
species having been observed in union. Mr. MacLachlan informs me (vide
Stett. Ent. Zeitung, 1867, s. 155) that when several species of
Phryganidae, which present strongly-pronounced differences of this
kind, were confined together by Dr. Aug. Meyer, they coupled, and
one pair produced fertile ova.
*(3) The Practical Entomologist, Philadelphia, vol. ii., May,
1867, p 88.
*(4) Mr. Walsh, ibid., p. 107.
*(5) Modern Classification of Insects, vol. ii., 1840, pp. 205, 206.
Mr. Walsh, who called my attention to the double use of the jaws, says
that he has repeatedly observed this fact.
The tarsi of the front-legs are dilated in many male beetles, or are
furnished with broad cushions of hairs; and in many genera of
water-beetles they are armed with a round flat sucker, so that the
male may adhere to the slippery body of the female. It is a much
more unusual circumstance that the females of some water-beetles
(Dytiscus) have their elytra deeply grooved, and in Acilius sulcatus
thickly set with hairs, as an aid to the male. The females of some
other water-beetles (Hydroporus) have their elytra punctured for the
same purpose.* In the male of Crabrocribrarius (see fig. 9), it is the
tibia which is dilated into a broad horny plate, with minute
membraneous dots, giving to it a singular appearance like that of a
riddle.*(2) In the male of Penthe (a genus of beetles) a few of the
middle joints of the antennae are dilated and furnished on the
inferior surface with cushions of hair, exactly like those on the
tarsi of the Carabidae, "and obviously for the same end." In male
dragon-flies, "the appendages at the tip of the tail are modified in
an almost infinite variety of curious patterns to enable them to
embrace the neck of the female." Lastly, in the males of many insects,
the legs are furnished with peculiar spines, knobs or spurs; or the
whole leg is bowed or thickened, but this is by no means invariably
a sexual character; or one pair, or all three pairs are elongated,
sometimes to an extravagant length.*(3)
* We have here a curious and inexplicable case of dimorphism, for
some of the females of four European species of Dysticus, and of
certain species of Hydroporus, have their elytra smooth; and no
intermediate gradations between the sulcated or punctured, and the
quite smooth elytra have been observed. See Dr. H. Schaum, as quoted
in the Zoologist, vols. v.-vi., 1847-48, p. 1896. Also Kirby and
Spence, Introduction to Entomology, vol. iii., 1826, p. 305.
*(2) Westwood, Modern Class., vol. ii., p. 193. The following
statement about Penthe, and others in inverted commas, are taken
from Mr. Walsh, Practical Entomologist, Philadelphia, vol. iii., p.
88.
*(3) Kirby and Spence, Introduct. &c., vol. iii., pp. 332-336.
The sexes of many species in all the orders present differences,
of which the meaning is not understood. One curious case is that of
a beetle (see fig. 10), the male of which has left mandible much
enlarged; so that the mouth is greatly distorted. In another
carabidous beetle, Eurygnathus,* we have the case, unique as far as
known to Mr. Wollaston, of the head of the female being much broader
and larger, though in a variable degree, than that of the male. Any
number of such cases could be given. They abound in the Lepidoptera:
one of the most extraordinary is that certain male butterflies have
their fore-legs more or less atrophied, with the tibiae and tarsi
reduced to mere rudimentary knobs. The wings, also, in the two sexes
often differ in neuration,*(2) and sometimes considerably in
outline, as in the Aricoris epitus, which was shewn to me in the
British Museum by Mr. A. Butler. The males of certain South American
butterflies have tufts of hair on the margins of the wings, and
horny excrescences on the discs of the posterior pair.*(3) In
several British butterflies, as shewn by Mr. Wonfor, the males alone
are in parts clothed with peculiar scales.
* Insecta Maderensia, 1854, page 20.
*(2) E. Doubleday, Annals and Mag. of Nat. Hist., vol. i., 1848,
p. 379. I may add that the wings in certain Hymenoptera (see Shuckard,
Fossorial Hymenoptera, 1837, pp. 39-43) differ in neuration
according to sex.
*(3) H. W. Bates, in Journal of Proc. Linn. Soc., vol. vi., 1862, p.
74. Mr. Wonfor's observations are quoted in Popular Science Review,
1868, p. 343.
The use of the bright light of the female glow-worm has been subject
to much discussion. The male is feebly luminous, as are the larvae and
even the eggs. It has been supposed by some authors that the light
serves to frighten away enemies, and by others to guide the male to
the female. At last, Mr. Belt* appears to have solved the
difficulty: he finds that all the Lampyridae which he has tried are
highly distasteful to insectivorous mammals and birds. Hence it is
in accordance with Mr. Bates' view, hereafter to be explained, that
many insects mimic the Lampyridae closely, in order to be mistaken for
them, and thus to escape destruction. He further believes that the
luminous species profit by being at once recognised as unpalatable. It
is probable that the same explanation may be extended to the
elaters, both sexes of which are highly luminous. It is not known
why the wings of the female glow-worm have not been developed; but
in her present state she closely resembles a larva, and as larvae
are so largely preyed on by many animals, we can understand why she
has been rendered so much more luminous and conspicuous than the male;
and why the larvae themselves are likewise luminous.
* The Naturalist in Nicaragua, 1874, pp. 316-320. On the
phosphorescence of the eggs, see Annals and Magazine of Natural
History, Nov., 1871, p. 372.
Difference in Size between the Sexes.- With insects of all kinds the
males are commonly smaller than the females; and this difference can
often be detected even in the larval state. So considerable is the
difference between the male and female cocoons of the silk-moth
(Bombyx mori), that in France they are separated by a particular
mode of weighing.* In the lower classes of the animal kingdom, the
greater size of the females seems generally to depend on their
developing an enormous number of ova; and this may to a certain extent
hold good with insects. But Dr. Wallace has suggested a much more
probable explanation. He finds, after carefully attending to the
development of the caterpillars of Bombyx cynthia and yamamai, and
especially to that of some dwarfed caterpillars reared from a second
brood on unnatural food, "that in proportion as the individual moth is
finer, so is the time required for its metamorphosis longer; and for
this reason the female, which is the larger and heavier insect, from
having to carry her numerous eggs, will be preceded by the male, which
is smaller and has less to mature."*(2) Now as most insects are
short-lived, and as they are exposed to many dangers, it would
manifestly be advantageous to the female to be impregnated as soon
as possible. This end would be gained by the males being first matured
in large numbers ready for the advent of the females; and this again
would naturally follow, as Mr. A. R. Wallace has remarked,*(3) through
natural selection; for the smaller males would be first matured, and
thus would procreate a large number of offspring which would inherit
the reduced size of their male parents, whilst the larger males from
being matured later would leave fewer offspring.
* Robinet, Vers a Soie, 1848, p. 207.
*(2) Transact. Ent. Soc., 3rd series, vol. v., p. 486.
*(3) Journal of Proc. Ent. Soc., Feb. 4, 1867, p. lxxi.
There are, however, exceptions to the rule of male insects being
smaller than the females: and some of these exceptions are
intelligible. Size and strength would be an advantage to the males,
which fight for the possession of the females; and in these cases,
as with the stagbeetle (Lucanus), the males are larger than the
females. There are, however, other beetles which are not known to
fight together, of which the males exceed the females in size; and the
meaning of this fact is not known; but in some of these cases, as with
the huge Dynastes and Megasoma, we can at least see that there would
be no necessity for the males to be smaller than the females, in order
to be matured before them, for these beetles are not short-lived,
and there would be ample time for the pairing of the sexes. So
again, male dragon-flies (Libellulidae) are sometimes sensibly larger,
and never smaller, than the females;* and as Mr. MacLachlan
believes, they do not generally pair with the females until a week
or fortnight has elapsed, and until they have assumed their proper
masculine colours. But the most curious case, shewing on what
complex and easily-overlooked relations, so trifling a character as
difference in size between the sexes may depend, is that of the
aculeate Hymenoptera; for Mr. F. Smith informs me that throughout
nearly the whole of this large group, the males, in accordance with
the general rule, are smaller than the females, and emerge about a
week before them; but amongst the bees, the males of Apis mellifica,
Anthidium manicatum, and Anthophora acervorum, and amongst the
fosseres, the males of the Methoca ichneumonides, are larger than
the females. The explanation of this anomaly is that a marriage flight
is absolutely necessary with these species, and the male requires
great strength and size in order to carry the female through the
air. Increased size has here been acquired in opposition to the
usual relation between size and the period of development, for the
males, though larger, emerge before the smaller females.
* For this and other statements on the size of the sexes, see
Kirby and Spence, ibid., vol. iii., p. 300; on the duration of life in
insects, see p. 344.
We will now review the several Orders, selecting such facts as
more particularly concern us. The Lepidoptera (butterflies and
moths) will be retained for a separate chapter.
Order: THYSANURA.- The members of this lowly organised order are
wingless, dull-coloured, minute insects, with ugly, almost
mis-shapen heads and bodies. Their sexes do not differ, but they are
interesting as shewing us that the males pay sedulous court to the
females even low down in the animal scale. Sir J. Lubbock* says: "It
is very amusing to see these little creatures (Smynthurus luteus)
coquetting together. The male, which is much smaller than the
female, runs round her, and they butt one another, standing face to
face and moving backward and forward like two playful lambs. Then
the female pretends to run away and the male runs after her with a
queer appearance of anger, gets in front and stands facing her
again; then she turns coyly round, but he, quicker and more active,
scuttles round too, and seems to whip her with his antennae; then
for a bit they stand face to face, play with their antennae, and
seem to be all in all to one another."
* Transact. Linnean Soc., vol. xxvi., 1868, p. 296.
Order: DIPTERA (Flies).- The sexes differ little in colour. The
greatest difference, known to Mr. F. Walker, is in the genus Bibio, in
which the males are blackish or quite black, and the females obscure
brownish-orange. The genus Elaphomyia, discovered by Mr. Wallace* in
New Guinea, is highly remarkable, as the males are furnished with
horns, of which the females are quite destitute. The horns spring from
beneath the eyes, and curiously resemble those of a stag, being either
branched or palmated. In one of the species, they equal the whole body
in length. They might be thought to be adapted for fighting, but as in
one species they are of a beautiful pink colour, edged with black,
with a pale central stripe, and as these insects have altogether a
very elegant appearance, it is perhaps more probable that they serve
as ornaments. That the males of some Diptera fight together is
certain; Prof. Westwood*(2) has several times seen this with the
Tipulae. The males of other Diptera apparently try to win the
females by their music: H. Muller*(3) watched for some time two
males of an Eristalis courting a female; they hovered above her, and
flew from side to side, making a high humming noise at the same
time. Gnats and mosquitoes (Culicidae) also seem to attract each other
by humming; and Prof. Mayer has recently ascertained that the hairs on
the antennae of the male vibrate in unison with the notes of a
tuning-fork, within the range of the sounds emitted by the female. The
longer hairs vibrate sympathetically with the graver notes, and the
shorter hairs with the higher ones. Landois also asserts that he has
repeatedly drawn down a whole swarm of gnats by uttering a
particular note. It may be added that the mental faculties of the
Diptera are probably higher than in most other insects, in
accordance with their highly-developed nervous System.*(4)
* The Malay Archipelago, vol. ii., 1869, p. 313.
*(2) Modern Classification of Insects, vol. ii., 1840, p. 526.
*(3) "Anwendung," &c., Verh. d. n. V. Jahrg. xxix. p. 80. Mayer,
in American Naturalist, 1874, p. 236.
*(4) See Mr. B. T. Lowne's interesting work, On the Anatomy of the
Blowfly, Musca vomitoria, 1870, p. 14. He remarks (p. 33) that, "the
captured flies utter a peculiar plaintive note, and that this sound
causes other flies to disappear."
Order: HEMIPTERA (Field-Bugs).- Mr. J. W. Douglas, who has
particularly attended to the British species, has kindly given me an
account of their sexual differences. The males of some species are
furnished with wings, whilst the females are wingless; the sexes
differ in the form of their bodies, elytra, antennae and tarsi; but as
the signification of these differences is unknown, they may be here
passed over. The females are generally larger and more robust than the
males. With British, and, as far as Mr. Douglas knows, with exotic
species, the sexes do not commonly differ much in colour; but in about
six British species the male is considerably darker than the female,
and in about four other species the female is darker than the male.
Both sexes of some species are beautifully coloured; and as these
insects emit an extremely nauseous odour, their conspicuous colours
may serve as a signal that they are unpalatable to insectivorous
animals. In some few cases their colours appear to be directly
protective: thus Prof. Hoffmann informs me that he could hardly
distinguish a small pink and green species from the buds on the trunks
of lime-trees, which this insect frequents.
Some species of Reduvidae make a stridulating noise; and, in the
case of Pirates stridulus, this is said* to be effected by the
movement of the neck within the prothoracic cavity. According to
Westring, Reduvius personatus also stridulates. But I have no reason
to suppose that this is a sexual character, excepting that with
non-social insects there seems to be no use for sound-producing
organs, unless it be as a sexual call.
* Westwood, Modern Classification of Insects, vol. ii., p. 473.
Order: HOMOPTERA.- Every one who has wandered in a tropical forest
must have been astonished at the din made by the male Cicadae. The
females are mute; as the Grecian poet Xenarchus says, "Happy the
cicadas live, since they all have voiceless wives." The noise thus
made could be plainly heard on board the Beagle, when anchored at a
quarter of a mile from the shore of Brazil; and Captain Hancock says
it can be heard at the distance of a mile. The Greeks formerly kept,
and the Chinese now keep these insects in cages for the sake of
their song, so that it must be pleasing to the ears of some men.*
The Cicadidae usually sing during the day, whilst the Fulgoridae
appear to be night-songsters. The sound, according to Landois,*(2)
is produced by the vibration of the lips of the spiracles, which are
set into motion by a current of air emitted from the tracheae; but
this view has lately been disputed. Dr. Powell appears to have
proved*(3) that it is produced by the vibration of a membrane, set
into action by a special muscle. In the living insect, whilst
stridulating, this membrane can be seen to vibrate; and in the dead
insect the proper sound is heard, if the muscle, when a little dried
and hardened, is pulled with the point of a pin. In the female the
whole complex musical apparatus is present, but is much less developed
than in the male, and is never used for producing sound.
* These particulars are taken from Westwood's Modern
Classification of Insects, vol. ii., 1840, p. 422. See, also, on the
Fulgoridae, Kirby and Spence, Introduct., vol. ii., p. 401.
*(2) Zeitschrift fur wissenschaft Zoolog., B. xvii., 1867, ss.
152-158.
*(3) Transactions of the New Zealand Institute, vol. v., 1873, p.
286.
With respect to the object of the music. Dr. Hartman, in speaking of
the Cicada septemdecim of the United States, says,* "The drums are now
(June 6th and 7th, 1851) heard in all directions. This I believe to be
the martial summons from the males. Standing in thick chestnut sprouts
about as high as my head, where hundreds were around me, I observed
the females coming around the drumming males." He adds, "This season
(Aug. 1868) a dwarf pear tree in my garden produced about fifty larvae
of C. pruinosa; and I several times noticed the females to alight near
a male while he was uttering his clanging notes." Fritz Muller
writes to me from S. Brazil that he has often listened to a musical
contest between two or three males of a species with a particularly
loud voice, seated at a considerable distance from each other: as soon
as one had finished his song, another immediately begun, and then
another. As there is so much rivalry between the males, it is probable
that the females not only find them by their sounds, but that, like
female birds, they are excited or allured by the male with the most
attractive voice.
* I am indebted to Mr. Walsh for having sent me this extract from
A Journal of the Doings of Cicada septemdecim, by Dr. Hartman.
I have not heard of any well-marked cases of ornamental
differences between the sexes of the Homoptera. Mr. Douglas informs me
that there are three British species, in which the male is black or
marked with black bands, whilst the females are pale-coloured or
obscure.
Order: ORTHOPTERA (Crickets and Grasshoppers).- The males in the
three saltatorial families in this Order are remarkable for their
musical powers, namely the Achetidae or crickets, the Locustidae for
which there is no equivalent English name, and the Acridiidae or
grasshoppers. The stridulation produced by some of the Locustidae is
so loud that it can be heard during the night at the distance of a
mile;* and that made by certain species is not unmusical even to the
human ear, so that the Indians on the Amazons keep them in wicker
cages. All observers agree that the sounds serve either to call or
excite the mute females. With respect to the migratory locusts of
Russia, Korte has given*(2) an interesting case of selection by the
female of a male. The males of this species (Pachytylus migratorius)
whilst coupled with the female stridulate from anger or jealousy, if
approached by other males. The house-cricket when surprised at night
uses its voice to warn its fellows.*(3) In North America the katydid
(Platyphyllum concavum, one of the Locustidae) is described*(4) as
mounting on the upper branches of a tree, and in the evening beginning
"his noisy babble, while rival notes issue from the neighbouring
trees, and the graves resound with the call of Katy-did-she-did the
live-long night." Mr. Bates, in speaking of the European field-cricket
(one of the Achetidae), says "the male has been observed to place
himself in the evening at the entrance of his burrow, and stridulate
until a female approaches, when the louder notes are succeeded by a
more subdued tone, whilst the successful musician caresses with his
antennae the mate he has won."*(5) Dr. Scudder was able to excite
one of these insects to answer him, by rubbing on a file with a
quill.*(6) In both sexes a remarkable auditory apparatus has been
discovered by von Siebold, situated in the front legs.*(7)
* L. Guilding, Transactions of the Linnean Society, vol. xv., p.
154.
*(2) I state this on the authority of Koppen, "Uber die Heuschrecken
in Sudrussland," 1866, p. 32, for I have in vain endeavoured to
procure Korte's work.
*(3) Gilbert White, Natural History of Selborne, vol. ii., 1825,
p. 262.
*(4) Harris, Insects of New England, 1842, p. 128.
*(5) The Naturalist on the Amazons, vol. i., 1863, p. 252. Mr. Bates
gives a very interesting discussion on the gradations in the musical
apparatus of the three families. See also Westwood, Modern
Classification of Insects, vol. ii., pp. 445 and 453.
*(6) Proceedings of the Boston Society of Natural History, vol. xi.,
April, 1868.
*(7) Nouveau Manuel d'Anat. Comp., French translat., tom. 1, 1850,
p. 567.
In the three families the sounds are differently produced. In the
males of the Achetidae both wing-covers have the same apparatus; and
this in the field cricket (see Gryllus campestris, fig. 11)
consists, as described by Landois,* of from 131 to 138 sharp,
transverse ridges or teeth (st) on the under side of one of the
nervures of the wing-cover. This toothed nervure is rapidly scraped
across a projecting, smooth, hard nervure (r) on the upper surface
of the opposite wing. First one wing is rubbed over the other, and
then the movement is reversed. Both wings are raised a little at the
same time, so as to increase the resonance. In some species the
wing-covers of the males are furnished at the base with a talc-like
plate.*(2) I here give a drawing (see fig. 12) of the teeth on the
under side of the nervure of another species of Gryllus, viz., G.
domesticus. With respect to the formation of these teeth, Dr. Gruber
has shown*(3) that they have been developed by the aid of selection,
from the minute scales and hairs with which the wings and body are
covered, and I came to the same conclusion with respect to those of
the Coleoptera. But Dr. Gruber further shews that their development is
in part directly due to the stimulus from the friction of one wing
over the other.
* Zeitschrift fur wissenschaft. Zoolog., B. xvii., 1867, s. 117.
*(2) Westwood, Modern Classification of Insects, vol. i., p. 440.
*(3) "Uber der Tonapparat der Locustiden, ein Beitrage zum
Darwinismus," Zeitschrift fur wissenschaft. Zoolog., B. xxii., 1872,
p. 100.
In the Locustidae the opposite wing-covers differ from each other in
structure (see fig. 13), and the action cannot, as in the last family,
be reversed. The left wing, which acts as the bow, lies over the right
wing which serves as the fiddle. One of the nervures (a) on the
under surface of the former is finely serrated, and is scraped
across the prominent nervures on the upper surface of the opposite
or right wing. In our British Phasgonura viridissima it appeared to me
that the serrated nervure is rubbed against the rounded hind-corner of
the opposite wing, the edge of which is thickened, coloured brown, and
very sharp. In the right wing, but not in the left, there is a
little plate, as transparent as talc, surrounded by nervures, and
called the speculum. In Ephippiger vitium, a member of this same
family, we have a curious subordinate modification; for the
wing-covers are greatly reduced in size, but "the posterior part of
the pro-thrax is elevated into a kind of dome over the wing-covers,
and which has probably the effect of increasing the sound."*
* Westwood Modern Classification of Insects, vol. i., p. 453.
We thus see that the musical apparatus is more differentiated or
specialised in the Locustidae (which include, I believe, the most
powerful performers in the Order), than in the Achetidae, in which
both wing-covers have the same structure and the same function.*
Landois, however, detected in one of the Locustidae, namely in
Decticus, a short and narrow row of small teeth, mere rudiments, on
the inferior surface of the right wing-cover, which underlies the
other and is never used as the bow. I observed the same rudimentary
structure on the under side of the right wing-cover in Phasgonura
viridissima. Hence we may infer with confidence that the Locustidae
are descended from a form, in which, as in the existing Achetidae,
both wing-covers had serrated nervures on the under surface, and could
be indifferently used as the bow; but that in the Locustidae the two
wing-covers gradually became differentiated and perfected, on the
principle of the division of labour, the one to act exclusively as the
bow, and the other as the fiddle. Dr. Gruber takes the same view,
and has shewn that rudimentary teeth are commonly found on the
inferior surface of the right wing. By what steps the more simple
apparatus in the Achetidae originated, we do not know, but it is
probable that the basal portions of the wing-covers originally
overlapped each other as they do at present; and that the friction
of the nervures produced a grating sound, as is now the case with
the wing-covers of the females.*(2) A grating sound thus
occasionally and accidentally made by the males, if it served them
ever so little as a love-call to the females, might readily have
been intensified through sexual selection, by variations in the
roughness of the nervures having been continually preserved.
* Landois, Zeitschrift fur wissenschaft. Zoolog., B. xvii., 1867,
ss. 121, 122.
*(2) Mr. Walsh also informs me that he has noticed that the female
of the Platyphyllum concavum, "when captured makes a feeble grating
noise by shuffling her wing-covers together."
In the last and third family, namely the Acridiidae or grasshoppers,
the stridulation is produced in a very different manner, and according
to Dr. Scudder, is not so shrill as in the preceding families. The
inner surface of the femur (see fig. 14, r) is furnished with a
longitudinal row of minute, elegant, lancet-shaped, elastic teeth,
from 85 to 93 in number;* and these are scraped across the sharp,
projecting nervures on the wing-covers, which are thus made to vibrate
and resound. Harris*(2) says that when one of the males begins to
play, he first "bends the shank of the hind-leg beneath the thigh,
where it is lodged in a furrow designed to receive it, and then
draws the leg briskly up and down. He does not play both fiddles
together, but alternately, first upon one and then on the other." In
many species, the base of the abdomen is hollowed out into a great
cavity which is believed to act as a resounding board. In Pneumora
(see fig. 15), a S. African genus belonging to the same family, we
meet with a new and remarkable modification; in the males a small
notched ridge projects obliquely from each side of the abdomen,
against which the hind femora are rubbed.*(3) As the male is furnished
with wings (the female being wingless), it is remarkable that the
thighs are not rubbed in the usual manner against the wing-covers; but
this may perhaps be accounted for by the unusually small size of the
hind-legs. I have not been able to examine the inner surface of the
thighs, which, judging from analogy, would be finely serrated. The
species of Pneumora have been more profoundly modified for the sake of
stridulation than any other orthopterous insect; for in the male the
whole body has been converted into a musical instrument, being
distended with air, like a great pellucid bladder, so as to increase
the resonance. Mr. Trimen informs me that at the Cape of Good Hope
these insects make a wonderful noise during the night.
* Landois, ibid., s. 113.
*(2) Insects of New England, 1842, p. 133.
*(3) Westwood, Modern Classification, vol i., p. 462.
In the three foregoing families, the females are almost always
destitute of an efficient musical apparatus. But there are a few
exceptions to this rule, for Dr. Gruber has shewn that both sexes of
Ephippiger vitium are thus provided; though the organs differ in the
male and female to a certain extent. Hence we cannot suppose that they
have been transferred from the male to the female, as appears to
have been the case with the secondary sexual characters of many
other animals. They must have been independently developed in the
two sexes, which no doubt mutually call to each other during the
season of love. In most other Locustidae (but not, according to
Landois, in Decticus) the females have rudiments of the stridulatory
organs proper to the male; from whom it is probable that these have
been transferred. Landois also found such rudiments on the under
surface of the wing-covers of the female Achetidae, and on the
femora of the female Acridiidae. In the Homoptera, also, the females
have the proper musical apparatus in a functionless state; and we
shall hereafter meet in other divisions of the animal kingdom with
many instances of structures proper to the male being present in a
rudimentary condition of the female.
Landois has observed another important fact, namely, that in the
females of the Acridiidae, the stridulating teeth on the femora remain
throughout life in the same condition in which they first appear
during the larval state in both sexes. In the males, on the other
hand, they become further developed, and acquire their perfect
structure at the last moult, when the insect is mature and ready to
breed.
From the facts now given, we see that the means by which the males
of the Orthoptera produce their sounds are extremely diversified,
and are altogether different from those employed by the Homoptera.*
But throughout the animal kingdom we often find the same object gained
by the most diversified means; this seems due to the whole
organisation having undergone multifarious changes in the course of
ages, and as part after part varied different variations were taken
advantage of for the same general purpose. The diversity of means
for producing sound in the three families of the Orthoptera and in the
Homoptera, impresses the mind with the high importance of these
structures to the males, for the sake of calling or alluring the
females. We need feel no surprise at the amount of modification
which the Orthoptera have undergone in this respect, as we now know,
from Dr. Scudder's remarkable discovery,*(2) that there has been
more than ample time. This naturalist has lately found a fossil insect
in the Devonian formation of New Brunswick, which is furnished with
"the well-known tympanum or stridulating apparatus of the male
Locustidae." The insect, though in most respects related to the
Neuroptera, appears, as is so often the case with very ancient
forms, to connect the two related Orders of the Neuroptera and
Orthoptera.
* Landois has recently found in certain Orthoptera rudimentary
structures closely similar to the sound-producing organs in the
Homoptera; and this is a surprising fact. See Zeitschrift fur
wissenschaft. Zoolog., B. xxii., Heft 3, 1871, p. 348.
*(2) Transactions, Entomological Society, 3rd series, vol. ii.
(Journal of Proceedings, p. 117).
I have but little more to say on the Orthoptera. Some of the species
are very pugnacious: when two male field-crickets (Gryllus campestris)
are confined together, they fight till one kills the other; and the
species of mantis are described as manoeuvring with their swordlike
front-limbs, like hussars with their sabres. The Chinese keep these
insects in little bamboo cages, and match them like game-cocks.*
With respect to colour, some exotic locusts are beautifully
ornamented; the posterior wings being marked with red, blue, and
black; but as throughout the Order the sexes rarely differ much in
colour, it is not probable that they owe their bright tints to
sexual selection. Conspicuous colours may be of use to these
insects, by giving notice that they are unpalatable. Thus it has
been observed*(2) that a bright-coloured Indian locust was
invariably rejected when offered to birds and lizards. Some cases,
however, are known of sexual differences in colour in this Order.
The male of an American cricket*(3) is described as being as white
as ivory, whilst the female varies from almost white to
greenish-yellow or dusky. Mr. Walsh informs me that the adult male
of Spectrum femoratum (one of the Phasmidae) "is of a shining
brownish-yellow colour; the adult female being of a dull, opaque,
cinereous brown; the young of both sexes being green." Lastly, I may
mention that the male of one curious kind of cricket*(4) is
furnished with "a long membranous appendage, which falls over the face
like a veil"; but what its use may be, is not known.
* Westwood, Modern Classification of Insects, vol. i., p. 427; for
crickets, p. 445.
*(2) Mr. Ch. Horne, in Proceedings of the Entomological Society, May
3, 1869, p. xii.
*(3) "The Oecanthus nivalis," Harris, Insects of New England,
1842, p. 124. The two sexes of OE. pellucidus of Europe differ, as I
hear from Victor Carus, in nearly the same manner.
*(4) Platyblemnus: Westwood, Modern Classification, vol. i., p. 447.
Order: NEUROPTERA.- Little need here be said, except as to colour.
In the Ephemeridae the sexes often differ slightly in their obscure
tints;* but it is not probable that the males are thus rendered
attractive to the females. The Libellulidae, or dragon-flies, are
ornamented with splendid green, blue, yellow, and vermilion metallic
tints; and the sexes often differ. Thus, as Prof. Westwood
remarks,*(2) the males of some of the Agrionidae, "are of a rich
blue with black wings, whilst the females are fine green with
colourless wings." But in Agrion ramburii these colours are exactly
reversed in the two sexes.*(3) In the extensive N. American genus of
Hetaerina, the males alone have a beautiful carmine spot at the base
of each wing. In Anax junius the basal part of the abdomen in the male
is a vivid ultramarine blue, and in the female grass-green. In the
allied genus Gomphus, on the other hand, and in some other genera, the
sexes differ but little in colour. In closely-allied forms
throughout the animal kingdom, similar cases of the sexes differing
greatly, or very little, or not at all, are of frequent occurrence.
Although there is so wide a difference in colour between the sexes
of many Libellulidae, it is often difficult to say which is the more
brilliant; and the ordinary coloration of the two sexes is reversed,
as we have just seen, in one species of Agrion. It is not probable
that their colours in any case have been gained as a protection. Mr.
MacLachlan, who has closely attended to this family, writes to me that
dragon-flies- the tyrants of the insect-world- are the least liable of
any insect to be attacked by birds or other enemies, and he believes
that their bright colours serve as a sexual attraction. Certain
dragon-flies apparently are attracted by particular colours: Mr.
Patterson observed*(4) that the Agrionidae, of which the males are
blue, settled in numbers on the blue float of a fishing line; whilst
two other species were attracted by shining white colours.
* B. D. Walsh, the "Pseudo-neuroptera of Illinois," in Proceedings
of the Entomological Society of Philadelphia, 1862, p. 361.
*(2) Modern Classification, vol. ii., p. 37.
*(3) Walsh, ibid., p. 381. I am indebted to this naturalist for
the following facts on Hetaerina, Anax, and Gomphus.
*(4) Transactions, Ent. Soc., vol. i., 1836, p. lxxxi.
It is an interesting fact, first noticed by Schelver, that, in
several genera belonging to two sub-families, the males on first
emergence from the pupal state, are coloured exactly like the females;
but that their bodies in a short time assume a conspicuous
milky-blue tint, owing to the exudation of a kind of oil, soluble in
ether and alcohol. Mr. MacLachlan believes that in the male of
Libellula depressa this change of colour does not occur until nearly a
fortnight after the metamorphosis, when the sexes are ready to pair.
Certain species of Neurothemis present, according to Brauer,* a
curious case of dimorphism, some of the females having ordinary wings,
whilst others have them "very richly netted, as in the males of the
same species." Brauer "explains the phenomenon on Darwinian principles
by the supposition that the close netting of the veins is a
secondary sexual character in the males, which has been abruptly
transferred to some of the females, instead of, as generally occurs,
to all of them." Mr. MacLachlan informs me of another instance of
dimorphism in several species of Agrion, in which some individuals are
of an orange colour, and these are invariably females. This is
probably a case of reversion; for in the true Libellulae, when the
sexes differ in colour, the females are orange or yellow; so that
supposing Agrion to be descended from some primordial form which
resembled the typical Libellulae in its sexual characters, it would
not be surprising that a tendency to vary in this manner should
occur in the females alone.
* See abstract in the Zoological Record for 1867, p. 450.
Although many dragon-flies are large, powerful, and fierce
insects, the males have not been observed by Mr. MacLachlan to fight
together, excepting, as he believes, in some of the smaller species of
Agrion. In another group in this Order, namely, the termites or
white ants, both sexes at the time of swarming may be seen running
about, "the male after the female, sometimes two chasing one female,
and contending with great eagerness who shall win the prize."* The
Atropos pulsatorius is said to make a noise with its jaws, which is
answered by other individuals.*(2)
* Kirby and Spence, Introduction to Entomology, vol. ii., 1818, p.
35.
*(2) Houzeau, Etudes sur Les Facultes Mentales des Animaux, tom. i.,
p. 104.
Order: HYMENOPTERA.- That inimitable observer, M. Fabre,* in
describing the habits of Cerceris, a wasp-like insect, remarks that
"fights frequently ensue between the males for the possession of
some particular female, who sits, an apparently unconcerned beholder
of the struggle for supremacy, and when the victory is decided,
quietly flies away in company with the conqueror." Westwood*(2) says
that the males of one of the saw-flies (Tenthredinae) "have been found
fighting together, with their mandibles locked." As M. Fabre speaks of
the males of Cerceris striving to obtain a particular female, it may
be well to bear in mind that insects belonging to this Order have
the power of recognising each other after long intervals of time,
and are deeply attached. For instance, Pierre Huber, whose accuracy no
one doubts, separated some ants, and when, after an interval of four
months, they met others which had formerly belonged to the same
community, they recognised and caressed one another with their
antennae. Had they been strangers they would have fought together.
Again, when two communities engage in a battle, the ants on the same
side sometimes attack each other in the general confusion, but they
soon perceive their mistake, and the one ant soothes the other.*(3)
* See an interesting article, "The Writings of Fabre," in Nat. Hist.
Review, April, 1862, p. 122.
*(2) Journal of Proceedings of Entomological Society, Sept. 7, 1863,
p. 169.
*(3) P. Huber, Recherches sur les Moeurs des Fourmis, 1810, pp.
150,165.
In this Order slight differences in colour, according to sex, are
common, but conspicuous differences are rare except in the family of
bees; yet both sexes of certain groups are so brilliantly coloured-
for instance in Chrysis, in which vermilion and metallic greens
prevail- that we are tempted to attribute the result to sexual
selection. In the Ichneumonidae, according to Mr. Walsh,* the males
are almost universally lighter-coloured than the females. On the other
hand, in the Tenthredinidae the males are generally darker than the
females. In the Siricidae the sexes frequently differ; thus the male
of Sirex juvencus is banded with orange, whilst the female is dark
purple; but it is difficult to say which sex is the more ornamented.
In Tremex columboe the female is much brighter coloured than the male.
I am informed by Mr. F. Smith, that the male ants of several species
are black, the females being testaceous.
* Proceedings of the Entomological Society of Philadelphia, 1866,
pp. 238, 239.
In the family of bees, especially in the solitary species, as I hear
from the same entomologist, the sexes often differ in colour. The
males are generally the brighter, and in Bombus as well as in Apathus,
much more variable in colour than the females. In Anthophora retusa
the male is of a rich fulvous-brown, whilst the female is quite black:
so are the females of several species of Xylocopa, the males being
bright yellow. On the other hand the females of some species, as of
Andraena fulva, are much brighter coloured than the males. Such
differences in colour can hardly be accounted for by the males being
defenceless and thus requiring protection, whilst the females are well
defended by their stings. H. Muller,* who has particularly attended to
the habits of bees, attributes these differences in colour in chief
part to sexual selection. That bees have a keen perception of colour
is certain. He says that the males search eagerly and fight for the
possession of the females; and he accounts through such contests for
the mandibles of the males being in certain species larger than
those of the females. In some cases the males are far more numerous
than the females, either early in the season, or at all times and
places, or locally; whereas the females in other cases are
apparently in excess. In some species the more beautiful males
appear to have been selected by the females; and in others the more
beautiful females by the males. Consequently in certain genera
(Muller, p. 42), the males of the several species differ much in
appearance, whilst the females are almost indistinguishable; in
other genera the reverse occurs. H. Muller believes (p. 82) that the
colours gained by one sex through sexual selection have often been
transferred in a variable degree to the other sex, just as the
pollen-collecting apparatus of the female has often been transferred
to the male, to whom it is absolutely useless.*(2)
* "Anwendung der Darwinschen Lehre auf Bienen," Verh. d. n. V.
Jahrg., xxix.
*(2) M. Perrier, in his article, "La Selection sexuelle d'apres
Darwin" (Revue Scientifique, Feb., 1873, p. 868), without apparently
having reflected much on the subject, objects that as the males of
social bees are known to be produced from unfertilised ova, they could
not transmit new characters to their male offspring. This is an
extraordinary objection. A female bee fertilised by a male, which
presented some character facilitating the union of the sexes, or
rendering him more attractive to the female, would lay eggs which
would produce only females; but these young females would next year
produce males; and will it be pretended that such males would not
inherit the characters of their male grandfathers? To take a case with
ordinary animals as nearly parallel as possible: if a female of any
white quadruped or bird were crossed by a male of a black breed, and
the male and female offspring were paired together, will it be
pretended that the grandchildren would not inherit a tendency to
blackness from their male grandfather? The acquirement of new
characters by the sterile worker-bees is a much more difficult case,
but I have endeavoured to show in my Origin of Species, how these
sterile beings are subjected to the power of natural selection.
Mutilla Europaea makes a stridulating noise; and according to
Goureau* both sexes have this power. He attributes the sound to the
friction of the third and preceding abdominal segments, and I find
that these surfaces are marked with very fine concentric ridges; but
so is the projecting thoracic collar into which the head
articulates, and this collar, when scratched with the point of a
needle, emits the proper sound. It is rather surprising that both
sexes should have the power of stridulating, as the male is winged and
the female wingless. It is notorious that bees express certain
emotions, as of anger, by the tone of their humming; and according
to H. Muller (p. 80), the males of some species make a peculiar
singing noise whilst pursuing the females.
* Quoted by Westwood, Modern Classification of Insects, vol. ii., p.
214.
Order: COLEOPTERA (Beetles).- Many beetles are coloured so as to
resemble the surfaces which they habitually frequent, and they thus
escape detection by their enemies. Other species, for instance
diamond-beetles, are ornamented with splendid colours, which are often
arranged in stripes, spots, crosses, and other elegant patterns.
Such colours can hardly serve directly as a protection, except in
the case of certain flower-feeding species; but they may serve as a
warning or means of recognition, on the same principle as the
phosphorescence of the glow-worm. As with beetles the colours of the
two sexes are generally alike, we have no evidence that they have been
gained through sexual selection; but this is at least possible, for
they have been developed in one sex and then transferred to the other;
and this view is even in some degree probable in those groups which
possess other well-marked secondary sexual characters. Blind
beetles, which cannot of course behold each other's beauty, never,
as I hear from Mr. Waterhouse, jr., exhibit bright colours, though
they often have polished coats; but the explanation of their obscurity
may be that they generally inhabit caves and other obscure stations.
Some longicorns, especially certain Prionidae, offer an exception to
the rule that the sexes of beetles do not differ in colour. Most of
these insects are large and splendidly coloured. The males in the
genus Pyrodes,* which I saw in Mr. Bates's collection, are generally
redder but rather duller than the females, the latter being coloured
of a more or less splendid golden-green. On the other hand, in one
species the male is golden-green, the female being richly tinted
with red and purple. In the genus Esmeralda the sexes differ so
greatly in colour that they have been ranked as distinct species; in
one species both are of a beautiful shining green, but the male has
a red thorax. On the whole, as far as I could judge, the females of
those Prionidae, in which the sexes differ, are coloured more richly
than the males, and this does not accord with the common rule in
regard to colour, when acquired through sexual selection.
* Pyrodes pulcherrimus, in which the sexes differ conspicuously, has
been described by Mr. Bates in Transact. Ent. Soc., 1869, p. 50. I
will specify the few other cases in which I have heard of a difference
in colour between the sexes of beetles. Kirby and Spence (Introduct.
to Entomology, vol. iii., p. 301) mention a Cantharis, Meloe, Rhagium,
and the Leptura testacea; the male of the latter being testaceous,
with a black thorax, and the female of a dull red all over. These
two latter beetles belong to the family of longicorns. Messrs. R.
Trimen and Waterhouse, jr., inform me of two lamellicorns, viz., a
Peritrichia and Trichius, the male of the latter being more
obscurely coloured than the female. In Tillus elongatus the male is
black, and the female always, as it is believed, of a dark blue
colour, with a red thorax. The male, also, of Orsodacna atra, as I
hear from Mr. Walsh, is black, the female (the so-called O.
ruficollis) having a rufous thorax.
A most remarkable distinction between the sexes of many beetles is
presented by the great horns which rise from the head, thorax, and
clypeus of the males; and in some few cases from the under surface
of the body. These horns, in the great family of the lamellicorns,
resemble those of various quadrupeds, such as stags, rhinoceroses,
&c., and are wonderful both from their size and diversified shapes.
Instead of describing them, I have given figures of the males and
females of some of the more remarkable forms. (See Figs. 16 to 20.)
The females generally exhibit rudiments of the horns in the form of
small knobs or ridges; but some are destitute of even the slightest
rudiment. On the other hand, the horns are nearly as well developed in
the female as in the male Phanaeus lancifer; and only a little less
well developed in the females of some other species of this genus
and of Copris. I am informed by Mr. Bates that the horns do not differ
in any manner corresponding with the more important characteristic
differences between the several subdivisions of the family: thus
within the same section of the genus Onthophagus, there are species
which have a single horn, and others which have two.
In almost all cases, the horns are remarkable for their excessive
variability; so that a graduated series can be formed, from the most
highly developed males to others so degenerate that they can barely be
distinguished from the females. Mr. Walsh* found that in Phanaeus
carnifex the horns were thrice as long in some males as in others. Mr.
Bates, after examining above a hundred males of Onthophagus rangifer
(see fig. 20), thought that he had at last discovered a species in
which the horns did not vary; but further research proved the
contrary.
* Proceedings of the Entomological Society of Philadephia, 1864,
p. 228.
The extraordinary size of the horns, and their widely different
structure in closely-allied forms, indicate that they have been formed
for some purpose; but their excessive variability in the males of
the same species leads to the inference that this purpose cannot be of
a definite nature. The horns do not show marks of friction, as if used
for any ordinary work. Some authors suppose* that as the males
wander about much more than the females, they require horns as a
defence against their enemies; but as the horns are often blunt,
they do not seem well adapted for defence. The most obvious conjecture
is that they are used by the males for fighting together; but the
males have never been observed to fight; nor could Mr. Bates, after
a careful examination of numerous species, find any sufficient
evidence, in their mutilated or broken condition, of their having been
thus used. If the males had been habitual fighters, the size of
their bodies would probably have been increased through sexual
selection, so as to have exceeded that of the females; but Mr.
Bates, after comparing the two sexes in above a hundred species of the
Copridae, did not find any marked difference in this respect amongst
well-developed individuals. In Lethrus, moreover, a beetle belonging
to the same great division of the lamellicorns, the males are known to
fight, but are not provided with horns, though their mandibles are
much larger than those of the female.
* Kirby and Spence, Introduction to Entomology, vol. iii., P. 300.
The conclusion that the horns have been acquired as ornaments is
that which best agrees with the fact of their having been so
immensely, yet not fixedly, developed,- as shewn by their extreme
variability in the same species, and by their extreme diversity in
closely-allied species. This view will at first appear extremely
improbable; but we shall hereafter find with many animals standing
much higher in the scale, namely fishes, amphibians, reptiles and
birds, that various kinds of crests, knobs, horns and combs have
been developed apparently for this sole purpose.
The males of Onitis furcifer (see fig. 21), and of some other
species of the genus, are furnished with singular projections on their
anterior femora, and with a great fork or pair of horns on the lower
surface of the thorax. Judging from other insects, these may aid the
male in clinging to the female. Although the males have not even a
trace of a horn on the upper surface of the body, yet the females
plainly exhibit a rudiment of a single horn on the head (see fig.
22, a), and of a crest (b) on the thorax. That the slight thoracic
crest in the female is a rudiment of a projection proper to the
male, though entirely absent in the male of this particular species,
is clear: for the female of Bubas bison (a genus which comes next to
Onitis) has a similar slight crest on the thorax, and the male bears a
great projection in the same situation. So, again, there can hardly be
a doubt that the little point (a) on the head of the female Onitis
furcifer, as well as on the head of the females of two or three allied
species, is a rudimentary representative of the cephalic horn, which
is common to the males of so many lamellicorn beetles, as in
Phanaeus (see fig. 18).
The old belief that rudiments have been created to complete the
scheme of nature is here so far from holding good, that we have a
complete inversion of the ordinary state of things in the family. We
may reasonably suspect that the males originally bore horns and
transferred them to the females in a rudimentary condition, as in so
many other lamellicorns. Why the males subsequently lost their
horns, we know not; but this may have been caused through the
principle of compensation, owing to the development of the large horns
and projections on the lower surface; and as these are confined to the
males, the rudiments of the upper horns on the females would not
have been thus obliterated.
The cases hitherto given refer to the lamellicorns, but the males of
some few other beetles, belonging to two widely distinct groups,
namely, the Curculionidae and Staphylinidae, are furnished with
horns - in the former on the lower surface of the body,* in the latter
on the upper surface of the head and thorax. In the Staphylinidae, the
horns of the males are extraordinarily variable in the same species,
just as we have seen with the lamellicorns. In Siagonium we have a
case of dimorphism, for the males can be divided into two sets,
differing greatly in the size of their bodies and in the development
of their horns, without intermediate gradations. In a species of
Bledius (see fig. 23), also belonging to the Staphylinidae,
Professor Westwood states that, "male specimens can be found in the
same locality in which the central horn of the thorax is very large,
but the horns of the head quite rudimental; and others, in which the
thoracic horn is much shorter, whilst the protuberances on the head
are long."*(2) Here we apparently have a case of compensation, which
throws light on that just given, of the supposed loss of the upper
horns by the males of Onitis.
* Kirby and Spence, Introduction to Entomology, vol. iii., p. 329.
*(2) Modern Classification of Insects, vol. i., p. 172: Siagonium,
p. 172. In the British Museum I noticed one male specimen of Siagonium
in an intermediate condition, so that the dimorphism is not strict.
Law of Battle.- Some male beetles, which seem ill-fitted for
fighting, nevertheless engage in conflicts for the possession of the
females. Mr. Wallace* saw two males of Leptorhynchus angustatus, a
linear beetle with a much elongated rostrum, "fighting for a female,
who stood close by busy at her boring. They pushed at each other
with their rostra, and clawed and thumped, apparently in the
greatest rage." The smaller male, however, "soon ran away,
acknowledging himself vanquished." In some few cases male beetles
are well adapted for fighting, by possessing great toothed
mandibles, much larger than those of the females. This is the case
with the common stag-beetle (Lucanus cervus), the males of which
emerge from the pupal state about a week before the other sex, so that
several may often be seen pursuing the same female. At this season
they engage in fierce conflicts. When Mr. A. H. Davis*(2) enclosed two
males with one female in a box, the larger male severely pinched the
smaller one, until he resigned his pretensions. A friend informs me
that when a boy he often put the males together to see them fight, and
he noticed that they were much bolder and fiercer than the females, as
with the higher animals. The males would seize hold of his finger,
if held in front of them, but not so the females, although they have
stronger jaws. The males of many of the Lucanidae as well as of the
above-mentioned Leptorhynchus, are larger and more powerful insects
than the females. The two sexes of Lethrus cephalotes (one of the
lamellicorns) inhabit the same burrow; and the male has larger
mandibles than the female. If, during the breeding-season, a strange
male attempts to enter the burrow, he is attacked; the female does not
remain passive, but closes the mouth of the burrow, and encourages her
mate by continually pushing him on from behind; and the battle lasts
until the aggressor is killed or runs away.*(3) The two sexes of
another lamellicorn beetle, the Ateuchus cicatricosus, live in
pairs, and seem much attached to each other; the male excites the
females to roll the balls of dung in which the ova are deposited;
and if she is removed, he becomes much agitated. If the male is
removed the female ceases all work, and as M. Brulerie*(4) believes,
would remain on the same spot until she died.
* The Malay Archipelago, vol. ii., 1869, p. 276. Riley, Sixth Report
on Insects of Missouri, 1874, p. 115.
*(2) Entomological Magazine, vol. i., 1833, p. 82. See also on the
conflicts of this species, Kirby and Spence, ibid., vol. iii., p. 314;
and Westwood, ibid., vol. i., p. 187.
*(3) Quoted from Fischer, in Dict. Class. d'Hist. Nat., tom. x.,
p. 324.
*(4) Ann. Soc. Entomolog. France, 1866, as quoted in Journal of
Travel, by A. Murray, 1868, p. 135.
The great mandibles of the male Lucanidae are extremely variable
both in size and structure, and in this respect resemble the horns
on the head and thorax of many male lamellicorns and Staphylinidae.
A perfect series can be formed from the best-provided to the
worst-provided or degenerate males. Although the mandibles of the
common stag-beetle, and probably of many other species, are used as
efficient weapons for fighting, it is doubtful whether their great
size can thus be accounted for. We have seen that they are used by the
Lucanus elaphus of N. America for seizing the female. As they are so
conspicuous and so elegantly branched, and as owing to their great
length they are not well adapted for pinching, the suspicion has
crossed my mind that they may in addition serve as an ornament, like
the horns on the head and thorax of the various species above
described. The male Chiasognathus grantii of S. Chile- a splendid
beetle belonging to the same family- has enormously developed
mandibles (see fig. 24); he is bold and pugnacious; when threatened he
faces round, opens his great jaws, and at the same time stridulates
loudly. But the mandibles were not strong enough to pinch my finger so
as to cause actual pain.
Sexual selection, which implies the possession of considerable
perceptive powers and of strong passions, seems to have been more
effective with the lamellicorns than with any other family of beetles.
With some species the males are provided with weapons for fighting;
some live in pairs and show mutual affection; many have the power of
stridulating when excited; many are furnished with the most
extraordinary horns, apparently for the sake of ornament; and some,
which are diurnal in their habits, are gorgeously coloured. Lastly,
several of the largest beetles in the world belong to this family,
which was placed by Linnaeus and Fabricius as the head of the Order.*
* Westwood, Modern Classification, vol. i., p. 184.
Stridulating organs.- Beetles belonging to many and widely
distinct families possess these organs. The sound thus produced can
sometimes be heard at the distance of several feet or even yards,* but
it is not comparable with that made by the Orthoptera. The rasp
generally consists of a narrow, slightly-raised surface, crossed by
very fine, parallel ribs, sometimes so fine as to cause iridescent
colours, and having a very elegant appearance under the microscope. In
some cases, as with Typhoeus, minute, bristly or scale-like
prominences, with which the whole surrounding surface is covered in
approximately parallel lines, could be traced passing into the ribs of
the rasp. The transition takes place by their becoming confluent and
straight, and at the same time more prominent and smooth. A hard ridge
on an adjoining part of the body serves as the scraper for the rasp,
but this scraper in some cases has been specially modified for the
purpose. It is rapidly moved across the rasp, or conversely the rasp
across the scraper.
* Wollaston, "On Certain Musical Curculionidae," Annals and Mag.
of Nat. Hist., vol. vi., 1860, p. 14.
These organs are situated in widely different positions. In the
carrion-beetles (Necrophorus) two parallel rasps (see r, fig. 25)
stand on the dorsal surface of the fifth abdominal segment, each rasp*
consisting of 126 to 140 fine ribs. These ribs are scraped against the
posterior margins of the elytra, a small portion of which projects
beyond the general outline. In many Crioceridae, and in Clythra
4-punctata (one of the Chrysomelidae), and in some Tenebrionidae,
&c.,*(2) the rasp is seated on the dorsal apex of the abdomen, on
the pygidium or propygidium, and is scraped in the same manner by
the elytra. In Heterocerus, which belongs to another family, the rasps
are placed on the sides of the first abdominal segment, and are
scraped by ridges on the femora.*(3) In certain Curculionidae and
Carabidae,*(4) the parts are completely reversed in position, for
the rasps are seated on the inferior surface of the elytra, near their
apices, or along their outer margins, and the edges of the abdominal
segments serve as the scrapers. In Pelobius Hermanni (one of
Dytiscidae or water-beetles) a strong ridge runs parallel and near
to the sutural margin of the elytra, and is crossed by ribs, coarse in
the middle part, but becoming gradually finer at both ends, especially
at the upper end; when this insect is held under water or in the
air, a stridulating noise is produced by the extreme horny margin of
the abdomen being scraped against the rasps. In a great number of
longhorned beetles (Longicornia) the organs are situated quite
otherwise, the rasp being on the meso-thorax, which is rubbed
against the pro-thorax; Landois counted 238 very fine ribs on the rasp
of Cerambyx heros.
* Landois, Zeitschrift fur wissenschaft. Zoolog., B. xvii., 1867, s.
127.
*(2) I am greatly indebted to Mr. G. B. Crotch for having sent me
many prepared specimens of various beetles belonging to these three
families and to others, as well as for valuable information. He
believes that the power of stridulation in the Clythra has not been
previously observed. I am also much indebted to Mr. E. W. Janson,
for information and specimens. I may add that my son, Mr. F. Darwin,
finds that Dermestes murinus stridulates, but he searched in vain
for the apparatus. Scolytus has lately been described by Dr. Chapman
as a stridulator, in the Entomologist's Monthly Magazine, vol. vi., p.
130.
*(3) Schiodte, translated, in Annals and Magazine of Natural
History, vol. xx., 1867, p. 37.
*(4) Westring has described (Kroyer, Naturhist. Tidskrift, B. ii.,
1848-49, p. 334) the stridulating organs in these two, as well as in
other families. In the Carabidae I have examined Ealphrus uliginosus
and Blethisa multipunctata, sent to me by Mr. Crotch. In Blethisa
the transverse ridges on the furrowed border of the abdominal
segment do not, as far as I could judge, come into play in scraping
the rasps on the elytra.
Many lamellicorns have the power of stridulating, and the organs
differ greatly in position. Some species stridulate very loudly, so
that when Mr. F. Smith caught a Trox sabulosus, a gamekeeper, who
stood by, thought he had caught a mouse; but I failed to discover
the proper organs in this beetle. In Geotrupes and Typhaeus, a
narrow ridge runs obliquely across (see r, fig. 26) the coxa of each
hindleg (having in G. stercorarius 84 ribs), which is scraped by a
specially projecting part of one of the abdominal segments. In the
nearly allied Copris lunaris, an excessively narrow fine rasp runs
along the sutural margin of the elytra, with another short rasp near
the basal outer margin; but in some other Coprini the rasp is
seated, according to Leconte, on the dorsal surface of the abdomen. In
Oryctes it is seated on the propygidium; and, according to the same
entomologist, in some other Dynastini, on the under surface of the
elytra. Lastly, Westring states that in Omaloplia brunnea the rasp
is placed on the pro-sternum, and the scraper on the meta-sternum, the
parts thus occupying the under surface of the body, instead of the
upper surface as in the Longicorns.
* I am indebted to Mr. Walsh, of Illinois, for having sent me
extracts from Leconte's Introduction to Entomology, pp. 101, 143.
We thus see that in the different coleopterous families the
stridulating organs are wonderfully diversified in position, but not
much in structure. Within the same family some species are provided
with these organs, and others are destitute of them. This diversity is
intelligible, if we suppose that originally various beetles made a
shuffling or hissing noise by the rubbing together of any hard and
rough parts of their bodies, which happened to be in contact; and that
from the noise thus produced being in some way useful, the rough
surfaces were gradually developed into regular stridulating organs.
Some beetles as they move, now produce, either intentionally or
unintentionally, a shuffling noise, without possessing any proper
organs for the purpose. Mr. Wallace informs me that the Euchirus
longimanus (a lamellicorn, with the anterior legs wonderfully
elongated in the male) "makes, whilst moving, a low hissing sound by
the protrusion and contraction of the abdomen; and when seized it
produces a grating sound by rubbing its hind-legs against the edges of
the elytra." The hissing sound is clearly due to a narrow rasp running
along the sutural margin of each elytron; and I could likewise make
the grating sound by rubbing the shagreened surface of the femur
against the granulated margin of the corresponding elytron; but I
could not here detect any proper rasp; nor is it likely that I could
have overlooked it in so large an insect. After examining Cychrus, and
reading what Westring has written about this beetle, it seems very
doubtful whether it possesses any true rasp, though it has the power
of emitting a sound.
From the analogy of the Orthoptera and Homoptera, I expected to find
the stridulating organs in the Coleoptera differing according to
sex; but Landois, who has carefully examined several species, observed
no such difference; nor did Westring; nor did Mr. G. R. Crotch in
preparing the many specimens which he had the kindness to send me. Any
difference in these organs, if slight, would, however, be difficult to
detect, on account of their great variability. Thus, in the first pair
of specimens of Necrophorus humator and of Pelobius which I
examined, the rasp was considerably larger in the male than in the
female; but not so with succeeding specimens. In Geotrupes
stercorarius the rasp appeared to me thicker, opaquer, and more
prominent in three males than in the same number of females; in order,
therefore, to discover whether the sexes differed in their power of
stridulating, my son, Mr. F. Darwin, collected fifty-seven living
specimens, which he separated into two lots, according as they made
a greater or less noise, when held in the same manner. He then
examined all these specimens, and found that the males were very
nearly in the same proportion to the females in both the lots. Mr.
F. Smith has kept alive numerous specimens of Monoynchus pseudacori
(Curculionidae), and is convinced that both sexes stridulate, and
apparently in an equal degree.
Nevertheless, the power of stridulating is certainly a sexual
character in some few Coleoptera. Mr. Crotch discovered that the males
alone of two species of Heliopathes (Tenebrionidae) possess
stridulating organs. I examined five males of H. gibbus, and in all
these there was a well-developed rasp, partially divided into two,
on the dorsal surface of the terminal abdominal segment; whilst in the
same number of females there was not even a rudiment of the rasp,
the membrane of this segment being transparent, and much thinner
than in the male. In H. cribratostriatus the male has a similar
rasp, excepting that it is not partially divided into two portions,
and the female is completely destitute of this organ; the male in
addition has on the apical margins of the elytra, on each side of
the suture, three or four short longitudinal ridges, which are crossed
by extremely fine ribs, parallel to and resembling those on the
abdominal rasp; whether these ridges serve as an independent rasp,
or as a scraper for the abdominal rasp, I could not decide: the female
exhibits no trace of this latter structure.
Again, in three species of the lamellicorn genus Oryctes, we have
a nearly parallel case. In the females of O. gryphus and nasicornis
the ribs on the rasp of the pro-pygidium are less continuous and
less distinct than in the males; but the chief difference is that
the whole upper surface of this segment, when held in the proper
light, is seen to be clothed with hairs, which are absent or are
represented by excessively fine down in the males. It should be
noticed that in all Coleoptera the effective part of the rasp is
destitute of hairs. In O. senegalensis the difference between the
sexes is more strongly marked, and this is best seen when the proper
abdominal segment is cleaned and viewed as a transparent object. In
the female the whole surface is covered with little separate crests,
bearing spines; whilst in the male these crests in proceeding
towards the apex, become more and more confluent, regular, and
naked; so that three-fourths of the segment is covered with
extremely fine parallel ribs, which are quite absent in the female. In
the females, however, of all three species of Oryctes, a slight
grating or stridulating sound is produced, when the abdomen of a
softened specimen is pushed backwards and forwards.
In the case of the Heliopathes and Oryctes there can hardly be a
doubt that the males stridulate in order to call or to excite the
females; but with most beetles the stridulation apparently serves both
sexes as a mutual call. Beetles stridulate under various emotions,
in the same manner as birds use their voices for many purposes besides
singing to their mates. The great Chiasognathus stridulates in anger
or defiance; many species do the same from distress or fear, if held
so that they cannot escape; by striking the hollow stems of trees in
the Canary Islands, Messrs. Wollaston and Crotch were able to discover
the presence of beetles belonging to the genus Acalles by their
stridulation. Lastly, the male Ateuchus stridulates to encourage the
female in her work, and from distress when she is removed.* Some
naturalists believe that beetles make this noise to frighten away
their enemies; but I cannot think that a quadruped or bird, able to
devour a large beetle, would be frightened by so slight a sound. The
belief that the stridulation serves as a sexual call is supported by
the fact that death-ticks (Anobium tessellatum) are well known to
answer each other's ticking, and, as I have myself observed, a tapping
noise artificially made. Mr. Doubleday also informs me that he has
sometimes observed a female ticking,*(2) and in an hour or two
afterwards has found her united with a male, and on one occasion
surrounded by several males. Finally, it is probable that the two
sexes of many kinds of beetles were at first enabled to find each
other by the slight shuffling noise produced by the rubbing together
of the adjoining hard parts of their bodies; and that as those males
or females which made the greatest noise succeeded best in finding
partners, rugosities on various parts of their bodies were gradually
developed by means of sexual selection into true stridulating organs.
* M. P. de la Brulerie, as quoted in Journal of Travel, A. Murray,
vol. i., 1868, p. 135.
*(2) According to Mr. Doubleday, "the noise is produced by the
insect raising itself on its legs as high as it can, and then striking
its thorax five or six times, in rapid succession, against the
substance upon which it is sitting." For references on this subject
see Landois, Zeitschrift fur wissen. Zoolog., B. xvii., s. 181.
Olivier says (as quoted by Kirby and Spence, Introduction to
Entomology, vol. ii., p. 395) that the female of Pimelia striata
produces a rather loud sound by striking her abdomen against any
hard substance, "and that the male, obedient to this call, soon
attends her, and they pair."
CHAPTER XI.
INSECTS, Continued- ORDER LEPIDOPTERA.
BUTTERFLIES AND MOTHS.
IN this great Order the most interesting points for us are the
differences in colour between the sexes of the same species, and
between the distinct species of the same genus. Nearly the whole of
the following chapter will be devoted to this subject; but I will
first make a few remarks on one or two other points. Several males may
often be seen pursuing and crowding round the same female. Their
courtship appears to be a prolonged affair, for I have frequently
watched one or more males pirouetting round a female until I was
tired, without seeing the end of the courtship. Mr. A. G. Butler
also informs me that he has several times watched a male courting a
female for a full quarter of an hour; but she pertinaciously refused
him, and at last settled on the ground and closed her wings, so as
to escape from his addresses.
Although butterflies are weak and fragile creatures, they are
pugnacious, and an emperor butterfly* has been captured with the
tips of its wings broken from a conflict with another male. Mr.
Collingwood, in speaking of the frequent battles between the
butterflies of Borneo, says, "They whirl round each other with the
greatest rapidity, and appear to be incited by the greatest ferocity."
* Apatura iris: The Entomologist's Weekly Intelligence, 1859, p.
139. For the Bornean butterflies, see C. Collingwood, Rambles of a
Naturalist, 1868, p. 183.
The Ageronia feronia makes a noise like that produced by a toothed
wheel passing under a spring catch, and which can be heard at the
distance of several yards: I noticed this sound at Rio de Janeiro,
only when two of these butterflies were chasing each other in an
irregular course, so that it is probably made during the courtship
of the sexes.*
* See my Journal of Researches, 1845, p. 33. Mr. Doubleday has
detected (Proc. Ent. Soc., March 3, 1845, p. 123) a peculiar
membranous sac at the base of the front wings, which is probably
connected with the production of the sound. For the case of
Thecophora, see Zoological Record, 1869, p. 401. For Mr. Buchanan
White's observations, the Scottish Naturalist, July, 1872, p. 214.
Some moths also produce sounds; for instance, the males
Theocophora fovea. On two occasions Mr. F. Buchanan White* heard a
sharp quick noise made by the male of Hylophila prasinana, and which
he believes to be produced, as in Cicada, by an elastic membrane,
furnished with a muscle. He quotes, also, Guenee, that Setina produces
a sound like the ticking of a watch, apparently by the aid of "two
large tympaniform vesicles, situated in the pectoral region"; and
these "are much more developed in the male than in the female."
Hence the sound-producing organs in the Lepidoptera appear to stand in
some relation with the sexual functions. I have not alluded to the
well-known noise made by the death's head sphinx, for it is
generally heard soon after the moth has emerged from its cocoon.
* The Scottish Naturalist, July, 1872, p. 213.
Giard has always observed that the musky odour, which is emitted
by two species of sphinx moths, is peculiar to the males;* and in
the higher classes we shall meet with many instances of the males
alone being odoriferous.
* Zoological Record, 1869, p. 347.
Every one must have admired the extreme beauty of many butterflies
and of some moths; and it may be asked, are their colours and
diversified patterns the result of the direct action of the physical
conditions to which these insects have been exposed, without any
benefit being thus derived? Or have successive variations been
accumulated and determined as a protection, or for some unknown
purpose, or that one sex may be attractive to the other? And, again,
what is the meaning of the colours being widely different in the males
and females of certain species, and alike in the two sexes of other
species of the same genus" Before attempting to answer these questions
a body of facts must be given.
With our beautiful English butterflies, the admiral, peacock, and
painted lady (Vanessae), as well as many others, the sexes are
alike. This is also the case with the magnificent Heliconidae, and
most of the Danaidae in the tropics. But in certain other tropical
groups, and in some of our English butterflies, as the purple emperor,
orange-tip, &c. (Apatura iris and Anthocharis cardamines), the sexes
differ either greatly or slightly in colour. No language suffices to
describe the splendour of the males of some tropical species. Even
within the same genus we often find species presenting extraordinary
differences between the sexes, whilst others have their sexes
closely alike. Thus in the South American genus Epicalia, Mr. Bates,
to whom I am indebted for most of the following facts, and for looking
over this whole discussion, informs me that he knows twelve species,
the two sexes of which haunt the same stations (and this is not always
the case with butterflies), and which, therefore, cannot have been
differently affected by external conditions.* In nine of these
twelve species the males rank amongst the most brilliant of all
butterflies, and differ so greatly from the comparatively plain
females that they were formerly placed in distinct genera. The females
of these nine species resemble each other in their general type of
coloration; and they likewise resemble both sexes of the species in
several allied genera found in various parts of the world. Hence we
may infer that these nine species, and probably all the others of
the genus, are descended from an ancestral form which was coloured
in nearly the same manner. In the tenth species the female still
retains the same general colouring, but the male resembles her, so
that he is coloured in a much less gaudy and contrasted manner than
the males of the previous species. In the eleventh and twelfth
species, the females depart from the usual type, for they are gaily
decorated almost like the males, but in a somewhat less degree.
Hence in these two latter species the bright colours of the males seem
to have been transferred to the females; whilst in the tenth species
the male has either retained or recovered the plain colours of the
female, as well as of the parent-form of the genus. The sexes in these
three cases have thus been rendered nearly alike, though in an
opposite manner. In the allied genus Eubagis, both sexes of some of
the species are plain-coloured and nearly alike; whilst with the
greater number the males are decorated with beautiful metallic tints
in a diversified manner, and differ much from their females. The
females throughout the genus retain the same general style of
colouring, so that they resemble one another much more closely than
they resemble their own males.
* See also Mr. Bates's paper in Proc. Ent. Soc. of Philadelphia,
1865, p. 206. Also Mr. Wallace on the same subject, in regard to
Diadema, in Transactions, Entomological Society, London, 1869, p. 278.
In the genus Papilio, all the species of the Aeneas group are
remarkable for their conspicuous and strongly contrasted colours,
and they illustrate the frequent tendency to gradation in the amount
of difference between the sexes. In a few species, for instance in
P. ascanius, the males and females are alike; in others the males
are either a little brighter, or very much more superb than the
females. The genus Junonia, allied to our Vanessae, offers a nearly
parallel case, for although the sexes of most of the species
resemble each other, and are destitute of rich colours, yet in certain
species, as in J. oenone, the male is rather more bright-coloured than
the female, and in a few (for instance J. andremiaja) the male is so
different from the female that he might be mistaken for an entirely
distinct species.
Another striking case was pointed out to me in the British Museum by
Mr. A. Butler, namely, one of the tropical American Theclae, in
which both sexes are nearly alike and wonderfully splendid; in another
species the male is coloured in a similarly gorgeous manner, whilst
the whole upper surface of the female is of a dull uniform brown.
Our common little English blue butterflies of the genus Lycaena,
illustrate the various differences in colour between the sexes, almost
as well, though not in so striking a manner, as the above exotic
genera. In Lycaena agestis both sexes have wings of a brown colour,
bordered with small ocellated orange spots, and are thus alike. In
L. oegon the wings of the males are of a fine blue, bordered with
black, whilst those of the female are brown, with a similar border,
closely resembling the wings of L. agestis. Lastly, in L. arion both
sexes are of a blue colour and are very like, though in the female the
edges of the wings are rather duskier, with the black spots plainer;
and in a bright blue Indian species both sexes are still more alike.
I have given the foregoing details in order to show, in the first
place, that when the sexes of butterflies differ, the male as a
general rule is the more beautiful, and departs more from the usual
type of colouring of the group to which the species belongs. Hence
in most groups the females of the several species resemble each
other much more closely than do the males. In some cases, however,
to which I shall hereafter allude, the females are coloured more
splendidly than the males. In the second place, these details have
been given to bring clearly before the mind that within the same
genus, the two sexes frequently present every gradation from no
difference in colour, to so great a difference that it was long before
the two were placed by entomologists in the same genus. In the third
place, we have seen that when the sexes nearly resemble each other,
this appears due either to the male having transferred his colours
to the female, or to the male having retained, or perhaps recovered,
the primordial colours of the group. It also deserves notice that in
those groups in which the sexes differ, the females usually somewhat
resemble the males, so that when the males are beautiful to an
extraordinary degree, the females almost invariably exhibit some
degree of beauty. From the many cases of gradation in the amount of
difference between the sexes, and from the prevalence of the same
general type of coloration throughout the whole of the same group,
we may conclude that the causes have generally been the same which
have determined the brilliant colouring of the males alone of some
species, and of both sexes of other species.
As so many gorgeous butterflies inhabit the tropics, it has often
been supposed that they owe their colours to the great heat and
moisture of these zones; but Mr. Bates* has shown by the comparison of
various closely-allied groups of insects from the temperate and
tropical regions, that this view cannot be maintained; and the
evidence becomes conclusive when brilliantly-coloured males and
plain-coloured females of the same species inhabit the same
district, feed on the same food, and follow exactly the same habits of
life. Even when the sexes resemble each other, we can hardly believe
that their brilliant and beautifully arranged colours are the
purposeless result of the nature of the tissues and of the action of
the surrounding conditions.
* The Naturalist on the Amazons, vol. i., 1863, p. 19.
With animals of all kinds, whenever colour has been modified for
some special purpose, this has been, as far as we can judge, either
for direct or indirect protection, or as an attraction between the
sexes. With many species of butterflies the upper surfaces of the
wings are obscure; and this in all probability leads to their escaping
observation and danger. But butterflies would be particularly liable
to be attacked by their enemies when at rest; and most kinds whilst
resting raise their wings vertically over their backs, so that the
lower surface alone is exposed to view. Hence it is this side which is
often coloured so as to imitate the objects on which these insects
commonly rest. Dr. Rossler, I believe, first noticed the similarity of
the closed wings of certain Vanessae and other butterflies to the bark
of trees. Many analogous and striking facts could be given. The most
interesting one is that recorded by Mr. Wallace* of a common Indian
and Sumatran butterfly (Kallima) which disappears like magic when it
settles on a bush; for it hides its head and antennae between its
closed wings, which, in form, colour and veining, cannot be
distinguished from a withered leaf with its footstalk. In some other
cases the lower surfaces of the wings are brilliantly coloured, and
yet are protective; thus in Thecla rubi the wings when closed are of
an emerald green, and resemble the young leaves of the bramble, on
which in spring this butterfly may often be seen seated. It is also
remarkable that in very many species in which the sexes differ greatly
in colour on their upper surface, the lower surface is closely similar
or identical in both sexes, and serves as a protection.*(2)
* See the interesting article in the Westminster Review, July, 1867,
p. 10. A woodcut of the Kallima is given by Mr. Wallace in Hardwicke's
Science Gossip, September 1867, p. 196.
*(2) Mr. G. Fraser, in Nature, April, 1871, p. 489.
Although the obscure tints both of the upper and under sides of many
butterflies no doubt serve to conceal them, yet we cannot extend
this view to the brilliant and conspicuous colours on the upper
surface of such species as our admiral and peacock Vanessae, our white
cabbage-butterflies (Pieris), or the great swallowtail Papilio which
haunts the open fens- for these butterflies are thus rendered
visible to every living creature. In these species both sexes are
alike; but in the common brimstone butterfly (Gonepteryx rhamni),
the male is of an intense yellow, whilst the female is much paler; and
in the orange-tip (Anthocharis cardamines) the males alone have
their wings tipped with bright orange. Both the males and females in
these cases are conspicuous, and it is not credible that their
difference in colour should stand in any relation to ordinary
protection. Prof. Weismann remarks,* that the female of one of the
Lycaenae expands her brow wings when she settles on the ground, and is
then almost invisible; the male, on the other hand, as if aware of the
danger incurred from the bright blue of the upper surface of his
wings, rests with them closed; and this shows that the blue colour
cannot be in any way protective. Nevertheless, it is probable that
conspicuous colours are indirectly beneficial to many species, as a
warning that they are unpalatable. For in certain other cases,
beauty has been gained through the imitation of other beautiful
species, which inhabit the same district and enjoy an immunity from
attack by being in some way offensive to their enemies; but then we
have to account for the beauty of the imitated species.
* Einfluss der Isolirung auf die Artbildung, 1872, p. 58.
As Mr. Walsh has remarked to me, the females of our orange-tip
butterfly, above referred to, and of an American species (Anth.
genutia) probably show us the primordial colours of the parent-species
of the genus; for both sexes of four or five widely-distributed
species are coloured in nearly the same manner. As in several previous
cases, we may here infer that it is the males of Anth. cardamines
and genutia which have departed from the usual type of the genus. In
the Anth. sara from California, the orange-tips to the wings have been
partially developed in the female; but they are paler than in the
male, and slightly different in some other respects. In an allied
Indian form, the Iphias glaucippe, the orange-tips are fully developed
in both sexes. In this Iphias, as pointed out to me by Mr. A.
Butler, the under surface of the wings marvellously resembles a
pale-coloured leaf; and in our English orange-tip, the under surface
resembles the flower-head of the wild parsley, on which the
butterfly often rests at night.* The same reason which compels us to
believe that the lower surfaces have here been coloured for the sake
of protection, leads us to deny that the wings have been tipped with
bright orange for the same purpose, especially when this character
is confined to the males.
* See the interesting observations by T. W. Wood, the Student,
Sept., 1868, p. 81.
Most moths rest motionless during the whole or greater part of the
day with their wings depressed; and the whole upper surface shaded and
coloured in an admirable manner, as Mr. Wallace has remarked, for
escaping detection. The front-wings of the Bombycidae,* when at
rest, generally overlap and conceal the hind-wings; so that the latter
might be brightly coloured without much risk; and they are in fact
often thus coloured. During flight, moths would often be able to
escape from their enemies; nevertheless, as the hind-wings are then
fully exposed to view, their bright must generally have been
acquired at some little risk. But the following fact shews how
cautious we ought to be in drawing conclusions on this head. The
common yellow under-wings (Triphoena) often fly about during the day
or early evening, and are then conspicuous from the colour of their
hind-wings. It would naturally be thought that this would be a
source of danger; but Mr. J. Jenner Weir believes that it actually
serves them as a means of escape, for birds strike at these brightly
coloured and fragile surfaces, instead of at the body. For instance,
Mr. Weir turned into his aviary a vigorous specimen of Triphoena
pronuba, which was instantly pursued by a robin; but the bird's
attention being caught by the coloured wings, the moth was not
captured until after about fifty attempts, and small portions of the
wings were repeatedly broken off. He tried the same experiment, in the
open air, with a swallow and T. fimbria; but the large size of this
moth probably interfered with its capture.*(2) We are thus reminded of
a statement made by Mr. Wallace,*(3) namely, that in the Brazilian
forests and Malayan islands, many common and highly-decorated
butterflies are weak flyers, though furnished with a broad expanse
of wing; and they "are often captured with pierced and broken wings,
as if they had been seized by birds, from which they had escaped: if
the wings had been much smaller in proportion to the body, it seems
probable that the insect would more frequently have been struck or
pierced in a vital part, and thus the increased expanse of the wings
may have been indirectly beneficial."
* Mr. Wallace in Harwicke's Science Gossip, September, 1867, p. 193.
*(2) See also, on this subject, Mr. Weir's paper in Transactions,
Entomological Society, 1869, p. 23.
*(3) Westminster Review, July, 1867, p. 16.
Display.- The bright colours of many butterflies and of some moths
are specially arranged for display, so that they may be readily
seen. During the night colours are not visible, and there can be no
doubt that the nocturnal moths, taken as a body, are much less gaily
decorated than butterflies, all of which are diurnal in their
habits. But the moths of certain families, such as the Zygaenidae,
several Sphingidae, Uraniidae, some Arctiidae and Saturniidae, fly
about during the day or early evening, and many of these are extremely
beautiful, being far brighter coloured than the strictly nocturnal
kinds. A few exceptional cases, however, of bright-coloured
nocturnal species have been recorded.*
* For instance, Lithosia; but Prof. Westwood (Modern Class. of
Insects, vol. ii., p. 390) seems surprised at this case. On the
relative colours of diurnal and nocturnal Lepidoptera, see ibid.,
pp. 333 and 392; also Harris, Treatise on the Insects of New
England, 1842, p. 315.
There is evidence of another kind in regard to display. Butterflies,
as before remarked, elevate their wings when at rest, but whilst
basking in the sunshine often alternately raise and depress them, thus
exposing both surfaces to full view; and although the lower surface is
often coloured in an obscure manner as a protection, yet in many
species it is as highly decorated as the upper surface, and
sometimes in a very different manner. In some tropical species the
lower surface is even more brilliantly coloured than the upper.* In
the English fritillaries (Argynnis) the lower surface alone is
ornamented with shining silver. Nevertheless, as a general rule, the
upper surface, which is probably more fully exposed, is coloured
more brightly and diversely than the lower. Hence the lower surface
generally affords to entomologists the more useful character for
detecting the affinities of the various species. Fritz Muller
informs me that three species of Castnia are found near his house in
S. Brazil: of two of them the hind-wings are obscure, and are always
covered by the front-wings when these butterflies are at rest; but the
third species has black hind-wings, beautifully spotted with red and
white, and these are fully expanded and displayed whenever the
butterfly rests. Other such cases could be added.
* Such differences between the upper and lower surfaces of the wings
of several species of Papilio may be seen in the beautiful plates to
Mr. Wallace's "Memoir on the Papilionidae of the Malayan Region," in
Transactions of the Linnean Society, vol. xxv., part i., 1865.
If we now turn to the enormous group of moths, which, as I hear from
Mr. Stainton, do not habitually expose the under surface of their
wings to full view, we find this side very rarely coloured with a
brightness greater than, or even equal to, that of the upper side.
Some exceptions to the rule, either real or apparent, must be noticed,
as the case of Hypopyra.* Mr. Trimen informs me that in Guenee's great
work, three moths are figured, in which the under surface is much
the more brilliant. For instance, in the Australian Gastrophora the
upper surface of the fore -wing is pale greyish-ochreous, while the
lower surface is magnificently ornamented by an ocellus of
cobalt-blue, placed in the midst of a black mark, surrounded by
orange-yellow, and this by bluish-white. But the habits of these three
moths are unknown; so that no explanation can be given of their
unusual style of colouring. Mr. Trimen also informs me that the
lower surface of the wings in certain other Geometrae*(2) and
quadrifid Noctuae are either more variegated or more brightly-coloured
than the upper surface; but some of these species have the habit of
"holding their wings quite erect over their backs, retaining them in
this position for a considerable time," and thus exposing the under
surface to view. Other species, when settled on the ground or herbage,
now and then suddenly and slightly lift up their wings. Hence the
lower surface of the wings being brighter than the upper surface in
certain moths is not so anomalous as it at first appears. The
Saturniidae include some of the most beautiful of all moths, their
wings being decorated, as in our British emperor moth, with fine
ocelli; and Mr. T. W. Wood*(3) observes that they resemble butterflies
in some of their movements; "for instance, in the gentle waving up and
down of the wings as if for display, which is more characteristic of
diurnal than of nocturnal Lepidoptera."
* See Mr. Wormald on this moth: Proceedings of the Entomological
Society, March 2, 1868.
*(2) See also an account of the S. American genus Erateina (one of
the Geometrae) in Transactions, Ent., Soc., new series, vol. v.,
pls. xv. and xvi.
*(3) Proc Ent. Soc. of London, July 6, 1868, p. xxvii.
It is a singular fact that no British moths which are brilliantly
coloured, and, as far as I can discover, hardly any foreign species,
differ much in colour according to sex; though this is the case with
many brilliant butterflies. The male, however, of one American moth,
the Saturnia io, is described as having its forewings deep yellow,
curiously marked with purplish-red spots; whilst the wings of the
female are purple-brown, marked with grey lines.* The British moths
which differ sexually in colour are all brown, or of various dull
yellow tints, or nearly white. In several species the males are much
darker than the females,*(2) and these belong to groups which
generally fly about during the afternoon. On the other hand, in many
genera, as Mr. Stainton informs me, the males have the hind-wings
whiter than those of the female- of which fact Agrotis exclamationis
offers a good instance. In the ghost-moth (Hepialus humuli) the
difference is more strongly marked; the males being white, and the
females yellow with darker markings.*(3) It is probable that in
these cases the males are thus rendered more conspicuous, and more
easily seen by the females whilst flying about in the dusk.
* Harris, Treatise, &c., edited by Flint, 1862, p. 395.
*(2) For instance, I observe in my son's cabinet that the males
are darker than the females in the Lasiocampa quercus Odonestis
potatoria, Hypogymna dispar, Dasychira pudibunda, and Cycnia
mendica. In this latter species the difference in colour between the
two sexes is strongly marked; and Mr. Wallace informs me that we
here have, as he believes, an instance of protective mimicry
confined to one sex, as will hereafter be more fully explained. The
white female of the Cycnia resembles the very common Spilosoma
menthrasti, both sexes of which are white; and Mr. Stainton observed
that this latter moth was rejected with utter disgust by a whole brood
of young turkeys, which were fond of eating other moths; so that if
the Cycnia was commonly mistaken by British birds for the Spilosoma,
it would escape being devoured, and its white deceptive colour would
thus be highly beneficial.
*(3) It is remarkable, that in the Shetland Islands the male of this
moth, instead of differing widely from the female, frequently
resembles her closely in colour (see Mr. MacLachlan, Transactions,
Entomological Society, vol. ii., 1866, p. 459). Mr. G. Fraser suggests
(Nature, April, 1871, p. 489) that at the season of the year when
the ghost-moth appears in these northern islands, the whiteness of the
males would not be needed to render them visible to the females in the
twilight night.
From the several foregoing facts it is impossible to admit that
the brilliant colours of butterflies, and of some few moths, have
commonly been acquired for the sake of protection. We have seen that
their colours and elegant patterns are arranged and exhibited as if
for display. Hence I am led to believe that the females prefer or
are most excited by the more brilliant males; for on any other
supposition the males would, as far as we can see, be ornamented to no
purpose. We know that ants and certain lamellicorn beetles are capable
of feeling an attachment for each other, and that ants recognise their
fellows after an interval of several months. Hence there is no
abstract improbability in the Lepidoptera, which probably stand nearly
or quite as high in the scale as these insects, having sufficient
mental capacity to admire bright colours. They certainly discover
flowers by colour. The humming-bird sphinx may often be seen to
swoop down from a distance on a bunch of flowers in the midst of green
foliage; and I have been assured by two persons abroad, that these
moths repeatedly visit flowers painted on the walls of a room, and
vainly endeavour to insert their proboscis into them. Fritz Muller
informs me that several kinds of butterflies in S. Brazil shew an
unmistakable preference for certain colours over others: he observed
that they very often visited the brilliant red flowers of five or
six genera of plants, but never the white or yellow flowering
species of the same and other genera, growing in the same garden;
and I have received other accounts to the same effect. As I hear
from Mr. Doubleday, the common white butterfly often flies down to a
bit of paper on the ground, no doubt mistaking it for one of its own
species. Mr. Collingwood* in speaking of the difficulty in
collecting certain butterflies in the Malay Archipelago, states that
"a dead specimen pinned upon a conspicuous twig will often arrest an
insect of the same species in its headlong flight, and bring it down
within easy reach of the net, especially if it be of the opposite
sex."
* Rambles of a Naturalist in the Chinese Seas, 1868, p. 182.
The courtship of butterflies is, as before remarked, a prolonged
affair. The males sometimes fight together in rivalry; and many may be
seen pursuing or crowding round the same female. Unless, then, the
females prefer one male to another, the pairing must be left to mere
chance, and this does not appear probable. If, on the other band,
the females habitually, or even occasionally, prefer the more
beautiful males, the colours of the latter will have been rendered
brighter by degrees, and will have been transmitted to both sexes or
to one sex, according to the law of inheritance which has prevailed.
The process of sexual selection will have been much facilitated, if
the conclusion can be trusted, arrived at from various kinds of
evidence in the supplement to the ninth chapter; namely, that the
males of many Lepidoptera, at least in the imago state, greatly exceed
the females in number.
Some facts, however, are opposed to the belief that female
butterflies prefer the more beautiful males; thus, as I have been
assured by several collectors, fresh females may frequently be seen
paired with battered, faded, or dingy males; but this is a
circumstance which could hardly fail often to follow from the males
emerging from their cocoons earlier than the females. With moths of
the family of the Bombycidae, the sexes pair immediately after
assuming the imago state; for they cannot feed, owing to the
rudimentary condition of their mouths. The females, as several
entomologists have remarked to me, lie in an almost torpid state,
and appear not to evince the least choice in regard to their partners.
This is the case with the common silk-moth (B. mori), as I have been
told by some continental and English breeders. Dr. Wallace, who has
had great experience in breeding Bombyx cynthia, is convinced that the
females evince no choice or preference. He has kept above 300 of these
moths together, and has often found the most vigorous females mated
with stunted males. The reverse appears to occur seldom; for, as he
believes, the more vigorous males pass over the weakly females, and
are attracted by those endowed with most vitality. Nevertheless, the
Bombycidae, though obscurely-coloured, are often beautiful to our eyes
from their elegant and mottled shades.
I have as yet only referred to the species in which the males are
brighter coloured than the females, and I have attributed their beauty
to the females for many generations having chosen and paired with
the more attractive males. But converse cases occur, though rarely, in
which the females are more brilliant than the males; and here, as I
believe, the males have selected the more beautiful females, and
have thus slowly added to their beauty. We do not know why in
various classes of animals the males of some few species have selected
the more beautiful females instead of having gladly accepted any
female, as seems to be the general rule in the animal kingdom: but if,
contrary to what generally occurs with the Lepidoptera, the females
were much more numerous than the males, the latter would be likely
to pick out the more beautiful females. Mr. Butler shewed me several
species of Callidryas in the British Museum, in some of which the
females equalled, and in others greatly surpassed the males in beauty;
for the females alone have the borders of their wings suffused with
crimson and orange, and spotted with black. The plainer males of these
species closely resemble each other, shewing that here the females
have been modified; whereas in those cases, where the males are the
more ornate, it is these which have been modified, the females
remaining closely alike.
In England we have some analogous cases, though not so marked. The
females alone of two species of Thecla have a bright-purple or
orange patch on their fore-wings. In Hipparchia the sexes do not
differ much; but it is the female of H. janira which has a conspicuous
light-brown patch on her wings; and the females of some of the other
species are brighter coloured than their males. Again, the females
of Colias edusa and hyale have "orange or yellow spots on the black
marginal border, represented in the males only by thin streaks"; and
in Pieris it is the females which "are ornamented with black spots
on the fore-wings, and these are only partially present in the males."
Now the males of many butterflies are known to support the females
during their marriage flight; but in the species just named it is
the females which support the males; so that the part which the two
sexes play is reversed, as is their relative beauty. Throughout the
animal kingdom the males commonly take the more active share in
wooing, and their beauty seems to have been increased by the females
having accepted the more attractive individuals; but with these
butterflies, the females take the more active part in the final
marriage ceremony, so that we may suppose that they likewise do so
in the wooing; and in this case we can understand how it is that
they have been rendered the more beautiful. Mr. Meldola, from whom the
foregoing statements have been taken, says in conclusion: "Though I am
not convinced of the action of sexual selection in producing the
colours of insects, it cannot be denied that these facts are
strikingly corroborative of Mr. Darwin's views."*
* Nature, April 27, 1871, p. 508. Mr. Meldola quotes Donzel, in Soc.
Ent. de France, 1837, p. 77, on the flight of butterflies whilst
pairing. See also Mr. G. Fraser, in Nature, April 20, 1871, p. 489, on
the sexual differences of several British butterflies.
As sexual selection primarily depends on variability, a few words
must be added on this subject. In respect to colour there is no
difficulty, for any number of highly variable Lepidoptera could be
named. One good instance will suffice. Mr. Bates shewed me a whole
series of specimens of Papilio sesostris and P. childrenae; in the
latter the males varied much in the extent of the beautifully
enamelled green patch on the fore-wings, and in the size of the
white mark, and of the splendid crimson stripe on the hind-wings; so
that there was a great contrast amongst the males between the most and
the least gaudy. The male of Papilio sesostris is much less
beautiful than of P. childrenae; and it likewise varies a little in
the size of the green patch on the fore-wings, and in the occasional
appearance of the small crimson stripe on the hind-wings, borrowed, as
it would seem, from its own female; for the females of this and of
many other species in the Aeneas group possess this crimson stripe.
Hence between the brightest specimens of P. sesostris and the
dullest of P. childrenae, there was but a small interval; and it was
evident that as far as mere variability is concerned, there would be
no difficulty in permanently increasing the beauty of either species
by means of selection. The variability is here almost confined to
the male sex; but Mr. Wallace and Mr. Bates have shewn* that the
females of some species are extremely variable, the males being nearly
constant. In a future chapter I shall have occasion to shew that the
beautiful eye-like spots, or ocelli, found on the wings of many
Lepidoptera, are eminently variable. I may here add that these
ocelli offer a difficulty on the theory of sexual selection; for
though appearing to us so ornamental, they are never present in one
sex and absent in the other, nor do they ever differ much in the two
sexes.*(2) This fact is at present inexplicable; but if it should
hereafter be found that the formation of an ocellus is due to some
change in the tissues of the wings, for instance, occurring at a
very early period of development, we might expect, from what we know
of the laws of inheritance, that it would be transmitted to both
sexes, though arising and perfected in one sex alone.
* Wallace on the "Papilionidae of the Malayan Region," in
Transact. Linn. Soc., vol. xxv., 1865, pp. 8, 36. A striking case of a
rare variety, strictly intermediate between two other well-marked
female varieties, is given by Mr. Wallace. See also Mr. Bates, in
Proc. Entomolog. Soc., Nov. 19, 1866, p. xl.
*(2) Mr. Bates was so kind as to lay this subject before the
Entomological Society, and I have received answers to this effect from
several entomologists.
On the whole, although many serious objections may be urged, it
seems probable that most of the brilliantly-coloured species of
Lepidoptera owe their colours to sexual selection, excepting in
certain cases, presently to be mentioned, in which conspicuous colours
have been gained through mimicry as a protection. From the ardour of
the male throughout the animal kingdom, he is generally willing to
accept any female; and it is the female which usually exerts a choice.
Hence, if sexual selection has been efficient with the Lepidoptera,
the male, when the sexes differ, ought to be the more brilliantly
coloured, and this undoubtedly is the case. When both sexes are
brilliantly coloured and resemble each other, the characters
acquired by the males appear to have been transmitted to both. We
are led to this conclusion by cases, even within the same genus, of
gradation from an extraordinary amount of difference to identity in
colour between the two sexes.
But it may be asked whether the difference in colour between the
sexes may not be accounted for by other means besides sexual
selection. Thus the males and females of the same species of butterfly
are in several cases known* to inhabit different stations, the
former commonly basking in the sunshine, the latter haunting gloomy
forests. It is therefore possible that different conditions of life
may have acted directly on the two sexes; but this is not probable*(2)
as in the adult state they are exposed to different conditions
during a very short period; and the larvae of both are exposed to
the same conditions. Mr. Wallace believes that the difference
between the sexes is due not so much to the males having been
modified, as to the females having in all or almost all cases acquired
dull colours for the sake of protection. It seems to me, on the
contrary, far more probable that it is the males which have been
chiefly modified through sexual selection, the females having been
comparatively little changed. We can thus understand how it is that
the females of allied species generally resemble one another so much
more closely than do the males. They thus shew us approximately the
primordial colouring of the parent-species of the group to which
they belong. They have, however, almost always been somewhat
modified by the transfer to them of some of the successive variations,
through the accumulation of which the males were rendered beautiful.
But I do not wish to deny that the females alone of some species may
have been specially modified for protection. In most cases the males
and females of distinct species will have been exposed during their
prolonged larval state to different conditions, and may have been thus
affected; though with the males any slight change of colour thus
caused will generally have been masked by the brilliant tints gained
through sexual selection. When we treat of birds, I shall have to
discuss the whole question, as to how far the differences in colour
between the sexes are due to the males having been modified through
sexual selection for ornamental purposes, or to the females having
been modified through natural selection for the sake of protection, so
that I will here say but little on the subject.
* H. W. Bates, The Naturalist on the Amazons, vol. ii., 1863, p.
228. A. R. Wallace, in Transactions, Linnean Society, vol. xxv., 1865,
p. 10.
*(2) On this whole subject see The Variation of Animals and Plants
under Domestication, 1868, vol. ii., chap. xxiii.
In all the cases in which the more common form of equal
inheritance by both sexes has prevailed, the selection of
bright-coloured males would tend to make the females
bright-coloured; and the selection of dull-coloured females would tend
to make the males dull. If both processes were carried on
simultaneously, they would tend to counteract each other; and the
final result would depend on whether a greater number of females
from being well protected by obscure colours, or a greater number of
males by being brightly-coloured and thus finding partners,
succeeded in leaving more numerous offspring.
In order to account for the frequent transmission of characters to
one sex alone, Mr. Wallace expresses his belief that the more common
form of equal inheritance by both sexes can be changed through natural
selection into inheritance by one sex alone, but in favour of this
view I can discover no evidence. We know from what occurs under
domestication that new characters often appear, which from the first
are transmitted to one sex alone; and by the selection of such
variations there would not be the slightest difficulty in giving
bright colours to the males alone, and at the same time or
subsequently, dull colours to the females alone. In this manner the
females of some butterflies and moths have, it is probable, been
rendered inconspicuous for the sake of protection, and widely
different from their males.
I am, however, unwilling without distinct evidence to admit that two
complex processes of selection, each requiring the transference of new
characters to one sex alone, have been carried on with a multitude
of species,- that the males have been rendered more brilliant by
beating their rivals, and the females more dull-coloured by having
escaped from their enemies. The male, for instance, of the common
brimstone butterfly (Gonepteryx), is of a far more intense yellow than
the female, though she is equally conspicuous; and it does not seem
probable that she specially acquired her pale tints as a protection,
though it is probable that the male acquired his bright colours as a
sexual attraction. The female of Anthocharis cardamines does not
possess the beautiful orange wing-tips of the male; consequently she
closely resembles the white butterflies (Pieris) so common in our
gardens; but we have no evidence that this resemblance is beneficial
to her. As, on the other hand, she resembles both sexes of several
other species of the genus inhabiting various quarters of the world,
it is probable that she has simply retained to a large extent her
primordial colours.
Finally, as we have seen, various considerations lead to the
conclusion that with the greater number of brilliantly-coloured
Lepidoptera it is the male which has been chiefly modified through
sexual selection; the amount of difference between the sexes mostly
depending on the form of inheritance which has prevailed.
Inheritance is govemed by so many unknown laws or conditions, that
it seems to us to act in a capricious manner;* and we can thus, to a
certain extent, understand how it is that with closely allied
species the sexes either differ to an astonishing degree, or are
identical in colour. As all the successive steps in the process of
variation are necessarily transmitted through the female, a greater or
less number of such steps might readily become developed in her; and
thus we can understand the frequent gradations from an extreme
difference to none at all between the sexes of allied species. These
cases of gradation, it may be added, are much too common to favour the
supposition that we here see females actually undergoing the process
of transition and losing their brightness for the sake of
protection; for we have every reason to conclude that at any one
time the greater number of species are in a fixed condition.
* The Variation of Animals and Plants under Domestication, vol. ii.,
chap. xii., p. 17.
Mimicry.- This principle was first made clear in an admirable
paper by Mr. Bates,* who thus threw a flood of light on many obscure
problems. It had previously been observed that certain butterflies
in S. America belonging to quite distinct families, resembled the
Heliconidae so closely in every stripe and shade of colour, that
they could not be distinguished save by an experienced entomologist.
As the Heliconidae are coloured in their usual manner, whilst the
others depart from the usual colouring of the groups to which they
belong, it is clear that the latter are the imitators, and the
Heliconidae the imitated. Mr. Bates further observed that the
imitating species are comparatively rare, whilst the imitated
abound, and that the two sets live mingled together. From the fact
of the Heliconidae being conspicuous and beautiful insects, yet so
numerous in individuals and species, he concluded that they must be
protected from the attacks of enemies by some secretion or odour;
and this conclusion has now been amply confirmed,*(2) especially by
Mr. Belt. Hence Mr. Bates inferred that the butterflies which
imitate the protected species have acquired their present marvellously
deceptive appearance through variation and natural selection, in order
to be mistaken for the protected kinds, and thus to escape being
devoured. No explanation is here attempted of the brilliant colours of
the imitated, but only of the imitating butterflies. We must account
for the colours of the former in the same general manner, as in the
cases previously discussed in this chapter. Since the publication of
Mr. Bates's paper, similar and equally striking facts have been
observed by Mr. Wallace in the Malayan region, by Mr. Trimen in
South Africa, and by Mr. Riley in the United States.*(3)
* Transact. Linn. Soc., vol. xxiii., 1862, p. 495.
*(2) Proc. Entomological Soc., Dec. 3, 1866, p. xlv.
*(3) Wallace, Transact. Linn. Soc., vol. xxv., 1865 p. i.; also,
Transact. Ent. Soc., vol. iv., 3rd series: 1867, p. 301. Trimen, Linn.
Transact., vol. xxvi., 1869, p. 497. Riley, Third Annual Report on the
Noxious Insects of Missouri, 1871, pp. 163-168. This latter essay is
valuable, as Mr. Riley here discusses all the objections which have
been raised against Mr. Bates's theory.
As some writers have felt much difficulty in understanding how the
first steps in the process of mimicry could have been effected through
natural selection, it may be well to remark that the process
probably commenced long ago between forms not widely dissimilar in
colour. In this case even a slight variation would be beneficial, if
it rendered the one species more like the other; and afterwards the
imitated species might be modified to an extreme degree through sexual
selection or other means, and if the changes were gradual, the
imitators might easily be led along the same track, until they
differed to an equally extreme degree from their original condition;
and they would thus ultimately assume an appearance or colouring
wholly unlike that of the other members of the group to which they
belonged. It should also be remembered that many species of
Lepidoptera are liable to considerable and abrupt variations in
colour. A few instances have been given in this chapter; and many more
may be found in the papers of Mr. Bates and Mr. Wallace.
With several species the sexes are alike, and imitate the two
sexes of another species. But Mr. Trimen gives, in the paper already
referred to, three cases in which the sexes of the imitated form
differ from each other in colour, and the sexes of the imitating
form differ in a like manner. Several cases have also been recorded
where the females alone imitate brilliantly-coloured and protected
species, the males retaining "the normal aspect of their immediate
congeners." It is here obvious that the successive variations by which
the female has been modified have been transmitted to her alone. It
is, however, probable that some of the many successive variations
would have been transmitted to, and developed in, the males had not
such males been eliminated by being thus rendered less attractive to
the females; so that only those variations were preserved which were
from the first strictly limited in their transmission to the female
sex. We have a partial illustration of these remarks in a statement by
Mr. Belt;* that the males of some of the Leptalides, which imitate
protected species, still retain in a concealed manner some of their
original characters. Thus in the males "the upper half of the lower
wing is of a pure white, whilst all the rest of the wings is barred
and spotted with black, red and yellow, like the species they mimic.
The females have not this white patch, and the males usually conceal
it by covering it with the upper wing, so that I cannot imagine its
being of any other use to them than as an attraction in courtship,
when they exhibit it to the females, and thus gratify their
deep-seated preference for the normal colour of the Order to which the
Leptalides belong."
* The Naturalist in Nicaragua, 1874, p. 385.
Bright Colours of Caterpillars.- Whilst reflecting on the beauty
of many butterflies, it occurred to me that some caterpillars were
splendidly coloured; and as sexual selection could not possibly have
here acted, it appeared rash to attribute the beauty of the mature
insect to this agency, unless the bright colours of their larvae could
be somehow explained. In the first place, it may be observed that
the colours of caterpillars do not stand in any close correlation with
those of the mature insect. Secondly, their bright colours do not
serve in any ordinary manner as a protection. Mr. Bates informs me, as
an instance of this, that the most conspicuous caterpillar which he
ever beheld (that of a sphinx) lived on the large green leaves of a
tree on the open llanos of South America; it was about four inches
in length, transversely banded with black and yellow, and with its
head, legs, and tail of a bright red. Hence it caught the eye of any
one who passed by, even at the distance of many yards, and no doubt
that of every passing bird.
I then applied to Mr. Wallace, who has an innate genius for
solving difficulties. After some consideration he replied: "Most
caterpillars require protection, as may be inferred from some kinds
being furnished with spines or irritating hairs, and from many being
coloured green like the leaves on which they feed, or being
curiously like the twigs of the trees on which they live." Another
instance of protection, furnished me by Mr. J. Mansel Weale, may be
added, namely, that there is a caterpillar of a moth which lives on
the mimosas in South Africa, and fabricates for itself a case quite
indistinguishable from the surrounding thorns. From such
considerations Mr. Wallace thought it probable that conspicuously
coloured caterpillars were protected by having a nauseous taste; but
as their skin is extremely tender, and as their intestines readily
protrude from a wound, a slight peck from the beak of a bird would
be as fatal to them as if they had been devoured. Hence, as Mr.
Wallace remarks, "distastefulness alone would be insufficient to
protect a caterpillar unless some outward sign indicated to its
would-be destroyer that its prey was a disgusting morsel." Under these
circumstances it would be highly advantageous to a caterpillar to be
instantaneously and certainly recognised as unpalatable by all birds
and other animals. Thus the most gaudy colours would be serviceable,
and might have been gained by variation and the survival of the most
easily-recognised individuals.
This hypothesis appears at first sight very bold, but when it was
brought before the Entomological Society* it was supported by
various statements; and Mr. J. Jenner Weir, who keeps a large number
of birds in an aviary, informs me that he has made many trials, and
finds no exception to the rule, that all caterpillars of nocturnal and
retiring habits with smooth skins, all of a green colour, and all
which imitate twigs, are greedily devoured by his birds. The hairy and
spinose kinds are invariably rejected, as were four
conspicuously-coloured species. When the birds rejected a caterpillar,
they plainly shewed, by shaking their heads, and cleansing their
beaks, that they were disgusted by the taste.*(2) Three conspicuous
kinds of caterpillars and moths were also given to some lizards and
frogs, by Mr. A. Butler, and were rejected, though other kinds were
eagerly eaten. Thus the probability of Mr. Wallace's view is
confirmed, namely, that certain caterpillars have been made
conspicuous for their own good, so as to be easily recognised by their
enemies, on nearly the same principle that poisons are sold in
coloured bottles by druggists for the good of man. We cannot, however,
at present thus explain the elegant diversity in the colours of many
caterpillars; but any species which had at some former period acquired
a dull, mottled, or striped appearance, either in imitation of
surrounding objects, or from the direct action of climate, &c., almost
certainly would not become uniform in colour when its tints were
rendered intense and bright; for in order to make a caterpillar merely
conspicuous, there would be no selection in any definite direction.
* Proceedings, Entomological Society, Dec. 3, 1866, p. xlv., and
March 4, 1867, p. lxxx.
*(2) See Mr. J. Jenner Weir's Paper on "Insects and Insectivorus
Birds," in Transact. Ent. Soc., 1869, p. 21; also Mr. Butler's
paper, ibid., p. 27. Mr. Riley has given analogous facts in the
Third Annual Report on the Noxious Insects of Missouri, 1871, p.
148. Some opposed cases are, however, given by Dr. Wallace and M. H.
d'Orville; see Zoological Record, 1869, p. 349.
Summary and Concluding Remarks on Insects.- Looking back to the
several Orders, we see that the sexes often differ in various
characters, the meaning of which is not in the least understood. The
sexes, also, often differ in their organs of sense and means of
locomotion, so that the males may quickly discover and reach the
females. They differ still oftener in the males possessing diversified
contrivances for retaining the females when found. We are, however,
here concerned only in a secondary degree with sexual differences of
these kinds.
In almost all the Orders, the males of some species, even of weak
and delicate kinds, are known to be highly pugnacious; and some few
are furnished with special weapons for fighting with their rivals. But
the law of battle does not prevail nearly so widely with insects as
with the higher animals. Hence it probably arises, that it is in
only a few cases that the males have been rendered larger and stronger
than the females. On the contrary, they are usually smaller, so that
they may be developed within a shorter time, to be ready in large
numbers for the emergence of the females.
In two families of the Homoptera and in three of the Orthoptera, the
males alone possess sound-producing organs in an efficient state.
These are used incessantly during the breeding-season, not only for
calling the females, but apparently for charming or exciting them in
rivalry with other males. No one who admits the agency of selection of
any kind, will, after reading the above discussion, dispute that these
musical instruments have been acquired through sexual selection. In
four other Orders the members of one sex, or more commonly of both
sexes, are provided with organs for producing various sounds, which
apparently serve merely as call-notes. When both sexes are thus
provided, the individuals which were able to make the loudest or
most continuous noise would gain partners before those which were less
noisy, so that their organs have probably been gained through sexual
selection. It is instructive to reflect on the wonderful diversity
of the means for producing sound, possessed by the males alone, or
by both sexes, in no less than six Orders. We thus learn how effectual
sexual selection has been in leading to modifications which sometimes,
as with the Homoptera, relate to important parts of the organisation.
From the reasons assigned in the last chapter, it is probable that
the great horns possessed by the males of many lamellicorn, and some
other beetles, have been acquired as ornaments. From the small size of
insects, we are apt to undervalue their appearance. If we could
imagine a male Chalcosoma (see fig. 16), with its polished bronzed
coat of mail, and its vast complex horns, magnified to the size of a
horse, or even of a dog, it would be one of the most imposing
animals in the world.
The colouring of insects is a complex and obscure subject. When
the male differs slightly from the female, and neither are
brilliantly-coloured, it is probable that the sexes have varied in a
slightly different manner, and that the variations have been
transmitted by each sex to the same without any benefit or evil thus
accruing. When the male is brilliantly-coloured and differs
conspicuously from the female, as with some dragonflies and many
butterflies, it is probable that he owes his colours to sexual
selection; whilst the female has retained a primordial or very ancient
type of colouring, slightly modified by the agencies before explained.
But in some cases the female has apparently been made obscure by
variations transmitted to her alone, as a means of direct
protection; and it is almost certain that she has sometimes been
made brilliant, so as to imitate other protected species inhabiting
the same district. When the sexes resemble each other and both are
obscurely coloured, there is no doubt that they have been in a
multitude of cases so coloured for the sake of protection. So it is in
some instances when both are brightly-coloured, for they thus
imitate protected species, or resemble surrounding objects such as
flowers; or they give notice to their enemies that they are
unpalatable. In other cases in which the sexes resemble each other and
are both brilliant, especially when the colours are arranged for
display, we may conclude that they have been gained by the male sex as
an attraction, and have been transferred to the female. We are more
especially led to this conclusion whenever the same type of coloration
prevails throughout a whole group, and we find that the males of
some species differ widely in colour from the females, whilst others
differ slightly or not at all with intermediate gradations
connecting these extreme states.
In the same manner as bright colours have often been partially
transferred from the males to the females, so it has been with the
extraordinary horns of many lamellicorn and some other beetles. So
again, the sound-producing organs proper to the males of the Homoptera
and Orthoptera have generally been transferred in a rudimentary, or
even in a nearly perfect condition, to the females; yet not
sufficiently perfect to be of any use. It is also an interesting fact,
as bearing on sexual selection, that the stridulating organs of
certain male Orthoptera are not fully developed until the last
moult; and that the colours of certain male dragon-flies are not fully
developed until some little time after their emergence from the
pupal state, and when they are ready to breed.
Sexual selection implies that the more attractive individuals are
preferred by the opposite sex; and as with insects, when the sexes
differ, it is the male which, with some rare exceptions, is the more
ornamented, and departs more from the type to which the species
belongs;- and as it is the male which searches eagerly for the female,
we must suppose that the females habitually or occasionally prefer the
more beautiful males, and that these have thus acquired their
beauty. That the females in most or all the Orders would have the
power of rejecting any particular male, is probable from the many
singular contrivances possessed by the males, such as great jaws,
adhesive cushions, spines, elongated legs, &c., for seizing the
female; for these contrivances shew that there is some difficulty in
the act, so that her concurrence would seem necessary. Judging from
what we know of the perceptive powers and affections of various
insects, there is no antecedent improbability in sexual selection
having come largely into play; but we have as yet no direct evidence
on this head, and some facts are opposed to the belief.
Nevertheless, when we see many males pursuing the same female, we
can hardly believe that the pairing is left to blind chance- that
the female exerts no choice, and is not influenced by the gorgeous
colours or other ornaments with which the male is decorated.
If we admit that the females of the Homoptera and Orthoptera
appreciate the musical tones of their male partners, and that the
various instruments have been perfected through sexual selection,
there is little improbability in the females of other insects
appreciating beauty in form or colour, and consequently in such
characters having been thus gained by the males. But from the
circumstance of colour being so variable, and from its having been
so often modified for the sake of protection, it is difficult to
decide in how large a proportion of cases sexual selection has
played a part. This is more especially difficult in those Orders, such
as Orthoptera, Hymenoptera, and Coleoptera, in which the two sexes
rarely differ much in colour; for we are then left to mere analogy.
With the Coleoptera, however, as before remarked, it is in the great
lamellicorn group, placed by some authors at the head of the Order,
and in which we sometimes see a mutual attachment between the sexes,
that we find the males of some species possessing weapons for sexual
strife, others furnished with wonderful horns, many with
stridulating organs, and others ornamented with splendid metallic
tints. Hence it seems probable that all these characters have been
gained through the same means, namely sexual selection. With
butterflies we have the best evidence, as the males sometimes take
pains to display their beautiful colours; and we cannot believe that
they would act thus, unless the display was of use to them in their
courtship.
When we treat of birds, we shall see that they present in their
secondary sexual characters the closest analogy with insects. Thus,
many male birds are highly pugnacious, and some are furnished with
special weapons for fighting with their rivals. They possess organs
which are used during the breeding-season for producing vocal and
instrumental music. They are frequently ornamented with combs,
horns, wattles and plumes of the most diversified kinds, and are
decorated with beautiful colours, all evidently for the sake of
display. We shall find that, as with insects, both sexes in certain
groups are equally beautiful, and are equally provided with
ornaments which are usually confined to the male sex. In other
groups both sexes are equally plain-coloured and unornamented. Lastly,
in some few anomalous cases, the females are more beautiful than the
males. We shall often find, in the same group of birds, every
gradation from no difference between the sexes, to an extreme
difference. We shall see that female birds, like female insects, often
possess more or less plain traces or rudiments of characters which
properly belong to the males and are of use only to them. The analogy,
indeed, in all these respects between birds and insects is curiously
close. Whatever explanation applies to the one class probably
applies to the other; and this explanation, as we shall hereafter
attempt to shew in further detail, is sexual selection.
CHAPTER XII.
SECONDARY SEXUAL CHARACTERS OF FISHES, AMPHIBIANS,
AND REPTILES.
WE have now arrived at the great sub-kingdom of the Vertebrata,
and will commence with the lowest class, that of fishes. The males
of plagiostomous fishes (sharks, rays) and of chimaeroid fishes are
provided with claspers which serve to retain the female, like the
various structures possessed by many of the lower animals. Besides the
claspers, the males of many rays have clusters of strong sharp
spines on their heads, and several rows along "the upper outer surface
of their pectoral fins." These are present in the males of some
species, which have other parts of their bodies smooth. They are
only temporarily developed during the breeding-season; and Dr. Gunther
suspects that they are brought into action as prehensile organs by the
doubling inwards and downwards of the two sides of the body. It is a
remarkable fact that the females and not the males of some species, as
of Raia clavata, have their backs studded with large hook-formed
spines.*
* Yarrell's Hist. of British Fishes, vol. ii., 1836, pp 417, 425,
436. Dr. Gunther informs me that the spines in R. clavata are peculiar
to the female.
The males alone of the capelin (Mallotus villosus, one of
Salmonidae), are provided with a ridge of closely-set, brush-like
scales, by the aid of which two males, one on each side, hold the
female, whilst she runs with great swiftness on the sandy beach, and
there deposits her spawn.* The widely distinct Monacanthus scopas
presents a somewhat analogous structure. The male, as Dr. Gunther
informs me, has a cluster of stiff, straight spines, like those of a
comb, on the sides of the tail; and these in a specimen six inches
long were nearly one and a half inches in length; the female has in
the same place a cluster of bristles, which may be compared with those
of a tooth-brush. In another species, M. peronii, the male has a brush
like that possessed by the female of the last species, whilst the
sides of the tail in the female are smooth. In some other species of
the same genus the tail can be perceived to be a little roughened in
the male and perfectly smooth in the female; and lastly in others,
both sexes have smooth sides.
* The American Naturalist, April, 1871, p. 119.
The males of many fish fight for the possession of the females. Thus
the male stickleback (Gasterosteus leiurus) has been described as "mad
with delight," when the female comes out of her hiding-place and
surveys the nest which he has made for her. "He darts round her in
every direction, then to his accumulated materials for the nest,
then back again in an instant; and as she does not advance he
endeavours to push her with his snout, and then tries to pull her by
the tail and side-spine to the nest."* The males are said to be
polygamists;*(2) they are extraordinarily bold and pugnacious,
whilst "the females are quite pacific." Their battles are at times
desperate; "for these puny combatants fasten tight on each other for
several seconds, tumbling over and over again until their strength
appears completely exhausted." With the rough-tailed stickleback (G.
trachurus) the males whilst fighting swim round and round each
other, biting and endeavouring to pierce each other with their
raised lateral spines. The same writer adds,*(3) "the bite of these
little furies is very severe. They also use their lateral spines
with such fatal effect, that I have seen one during a battle
absolutely rip his opponent quite open, so that he sank to the
bottom and died." When a fish is conquered, "his gallant bearing
forsakes him; his gay colours fade away; and he hides his disgrace
among his peaceable companions, but is for some time the constant
object of his conqueror's persecution."
* See Mr, R. Warington's interesting articles in Annals and Magazine
of Natural History, October, 1852, and November, 1855.
*(2) Noel Humphreys. River Gardens, 1857.
*(3) Loudon's Magazine of Natural History, vol. iii., 1830, p. 331.
The male salmon is as pugnacious as the little stickleback; and so
is the male trout, as I hear from Dr. Gunther. Mr. Shaw saw a
violent contest between two male salmon which lasted the whole day;
and Mr. R. Buist, Superintendent of Fisheries, informs me that he
has often watched from the bridge at Perth the males driving away
their rivals, whilst the females were spawning The males "are
constantly fighting and tearing each other on the spawning-beds, and
many so injure each other as to cause the death of numbers, many being
seen swimming near the banks of the river in a state of exhaustion,
and apparently in a dying state."* Mr. Buist informs me, that in
June 1868, the keeper of the Stormontfield breeding-ponds visited
the northern Tyne and found about 300 dead salmon, all of which with
one exception were males; and he was convinced that they had lost
their lives by fighting.
* The Field, June 29, 1867. For Mr. Shaw's statements, see Edinburgh
Review, 1843. Another experienced observer (Scrope's Days of Salmon
Fishing, p. 60) remarks that like the stag, the male would, if he
could, keep all other males away.
The most curious point about the male salmon is that during the
breeding-season, besides a slight change in colour, "the lower jaw
elongates, and a cartilaginous projection turns upwards from the
point, which, when the jaws are closed, occupies a deep cavity between
the intermaxillary bones of the upper jaw."* (See figs. 27 and 28.) In
our salmon this change of structure lasts only during the
breeding-season; but in the Salmo lycaodon of N. W. America the
change, as Mr. J. K. Lord*(2) believes, is permanent, and best
marked in the older males which have previously ascended the rivers.
In these old males the jaw becomes developed into an immense hook-like
projection, and the teeth grow into regular fangs, often more than
half an inch in length. With the European salmon, according to Mr.
Lloyd,*(3) the temporary hook-like structure serves to strengthen
and protect the jaws, when one male charges another with wonderful
violence; but the greatly developed teeth of the male American
salmon may be compared with the tusks of many male mammals, and they
indicate an offensive rather than a protective purpose.
* Yarrell, History of British Fishes, vol. ii., 1836, p. 10.
*(2) The Naturalist in Vancouver's Island, vol. i., 1866, p. 54.
*(3) Scandinavian Adventures, vol. i., 1854, pp. 100, 104.
The salmon is not the only fish in which the teeth differ in the two
sexes; as this is the case with many rays. In the thornback (Raia
clavata) the adult male has sharp, pointed teeth, directed
backwards, whilst those of the female are broad and flat, and form a
pavement; so that these teeth differ in the two sexes of the same
species more than is usual in distinct genera of the same family.
The teeth of the male become sharp only when he is adult: whilst young
they are broad and flat like those of the female. As so frequently
occurs with secondary sexual characters, both sexes of some species of
rays (for instance R. batis), when adult, possess sharp pointed teeth;
and here a character, proper to and primarily gained by the male,
appears to have been transmitted to the offspring of both sexes. The
teeth are likewise pointed in both sexes of R. maculata, but only when
quite adult; the males acquiring them at an earlier age than the
females. We shall hereafter meet with analogous cases in certain
birds, in which the male acquires the plumage common to both sexes
when adult, at a somewhat earlier age than does the female. With other
species of rays the males even when old never possess sharp teeth, and
consequently the adults of both sexes are provided with broad, flat
teeth like those of the young, and like those of the mature females of
the above-mentioned species.* As the rays are bold, strong and
voracious fish, we may suspect that the males require their sharp
teeth for fighting with their rivals; but as they possess many parts
modified and adapted for the prehension of the female, it is
possible that their teeth may be used for this purpose.
* See Yarrell's account of the rays in his History of British
Fishes, vol. ii., 1836, p. 416, with an excellent figure, and pp. 422,
432.
In regard to size, M. Carbonnier* maintains that the female of
almost all fishes is larger than the male; and Dr. Gunther does not
know of a single instance in which the male is actually larger than
the female. With some cyprinodonts the male is not even half as large.
As in many kinds of fishes the males habitually fight together, it
is surprising that they have not generally become larger and
stronger than the females through the effects of sexual selection. The
males suffer from their small size, for according to M. Carbonnier,
they are liable to be devoured by the females of their own species
when carnivorous, and no doubt by other species. Increased size must
be in some manner of more importance to the females, than strength and
size are to the males for fighting with other males; and this
perhaps is to allow of the production of a vast number of ova.
* As quoted in the Farmer, 1868, p. 369.
In many species the male alone is ornamented with bright colours; or
these are much brighter in the male than the female. The male, also,
is sometimes provided with appendages which appear to be of no more
use to him for the ordinary purposes of life, than are the tail
feathers to the peacock. I am indebted for most of the following facts
to the kindness of Dr. Gunther. There is reason to suspect that many
tropical fishes differ sexually in colour and structure; and there are
some striking cases with our British fishes. The male Callionymus lyra
has been called the gemmeous dragonet "from its brilliant gem-like
colours." When fresh caught from the sea the body is yellow of various
shades, striped and spotted with vivid blue on the head; the dorsal
fins are pale brown with dark longitudinal bands; the ventral, caudal,
and anal fins being bluish-black. The female, or sordid dragonet,
was considered by Linnaeus, and by many subsequent naturalists, as a
distinct species; it is of a dingy reddish-brown, with the dorsal
fin brown and the other fins white. The sexes differ also in the
proportional size of the head and mouth, and in the position of the
eyes;* but the most striking difference is the extraordinary
elongation in the male (see fig. 29) of the dorsal fin. Mr. W. Saville
Kent remarks that this "singular appendage appears from my
observations of the species in confinement, to be subservient to the
same end as the wattles, crests, and other abnormal adjuncts of the
male in gallinaceous birds, for the purpose of fascinating their
mates."*(2) The young males resemble the adult females in structure
and colour. Throughout the genus Callionymus,*(3) the male is
generally much more brightly spotted than the female, and in several
species, not only the dorsal, but the anal fin is much elongated in
the males.
* I have drawn up this description from Yarrell's British Fishes,
vol. i., 1836, pp. 261 and 266.
*(2) Nature, July, 1873, p. 264.
*(3) Catalogue of Acanth. Fishes in the British Museum, by Dr.
Gunther, 1861, pp. 138-151.
The male of the Cottus scorpius, or sea-serpent, is slenderer and
smaller than the female. There is also a great difference in colour
between them. It is difficult, as Mr. Lloyd* remarks, "for any one,
who has not seen this fish during the spawning-season, when its hues
are brightest, to conceive the admixture of brilliant colours with
which it, in other respects so ill-favoured, is at that time
adorned. Both sexes of the Labrus mixtus, although very different in
colour, are beautiful; the male being orange with bright blue stripes,
and the female bright red with some black spots on the back.
* Game Birds of Sweden, &c., 1867, p. 466.
In the very distinct family of the Cyprinodontidae- inhabitants of
the fresh waters of foreign lands- the sexes sometimes differ much
in various characters. In the male of the Mollienesia petenensis,* the
dorsal fin is greatly developed and is marked with a row of large,
round, ocellated, bright-coloured spots; whilst the same fin in the
female is smaller, of a different shape, and marked only with
irregularly curved brown spots. In the male the basal margin of the
anal fin is also a little produced and dark coloured. In the male of
an allied form, the Xiphophorus Hellerii (see fig. 30), the inferior
margin of the caudal fin is developed into a long filament, which,
as I hear from Dr. Gunther, is striped with bright colours. This
filament does not contain any muscles, and apparently cannot be of any
direct use to the fish. As in the case of the Callionymus, the males
whilst young resemble the adult females in colour and structure.
Sexual differences such as these may be strictly compared with those
which are so frequent with gallinaceous birds.*(2)
* With respect to this and the following species I am indebted to
Dr. Gunther for information: see also his paper on the "Fishes of
Central America," in Transact. Zoological Soc., vol. vi., 1868, p.
485.
*(2) Dr. Gunther makes this remark, Catalogue of Fishes in the
British Museum, vol. iii., 1861, p. 141.
In a siluroid fish, inhabiting the fresh waters of South America,
the Plecostomus barbatus* (see fig. 31), the male has its mouth and
interoperculum fringed with a beard of stiff hairs, of which the
female shows hardly a trace. These hairs are of the nature of
scales. In another species of the same genus, soft flexible
tentacles project from the front part of the head of the male, which
are absent in the female. These tentacles are prolongations of the
true skin, and therefore are not homologous with the stiff hairs of
the former species; but it can hardly be doubted that both serve the
same purpose. What this purpose may be, is difficult to conjecture;
ornament does not here seem probable, but we can hardly suppose that
stiff hairs and flexible filaments can be useful in any ordinary way
to the males alone. In that strange monster, the Chimaera monstrosa,
the male has a hook-shaped bone on the top of the head, directed
forwards, with its end rounded and covered with sharp spines; in the
female "this crown is altogether absent," but what its use may be to
the male is utterly unknown.*(2)
* See Dr. Gunther on this genus, in Proceedings of the Zoological
Society, 1868, p. 232.
*(2) F. Buckland, in Land and Water, July, 1868, p. 377, with a
figure. Many other cases could be added of structures peculiar to
the male, of which the uses are not known.
The structures as yet referred to are permanent in the male after he
has arrived at maturity; but with some blennies, and in another allied
genus,* a crest is developed on the head of the male only during the
breeding-season, and the body at the same time becomes more
brightly-coloured. There can be little doubt that this crest serves as
a temporary sexual ornament, for the female does not exhibit a trace
of it. In other species of the same genus both sexes possess a
crest, and in at least one species neither sex is thus provided. In
many of the Chromidae, for instance in Geophagus and especially in
Cichla, the males, as I hear from Professor Agassiz,*(2) have a
conspicuous protuberance on the forehead, which is wholly wanting in
the females and in the young males. Professor Agassiz adds, "I have
often observed these fishes at the time of spawning when the
protuberance is largest, and at other seasons when it is totally
wanting, and the two sexes shew no difference whatever in the
outline of the profile of the head. I never could ascertain that it
subserves any special function, and the Indians on the Amazon know
nothing about its use." These protuberances resemble, in their
periodical appearance, the fleshy carbuncles on the heads of certain
birds; but whether they serve as ornaments must remain at present
doubtful.
* Dr. Gunther, Catalogue of Fishes, vol. iii., pp. 221 and 240.
*(2) See also A Journey in Brazil, by Prof. and Mrs. Agassiz,
1868, p. 220.
I hear from Professor Agassiz and Dr. Gunther, that the males of
those fishes, which differ permanently in colour from the females,
often become more brilliant during the breeding-season. This is
likewise the case with a multitude of fishes, the sexes of which are
identical in colour at all other seasons of the year. The tench,
roach, and perch may be given as instances. The male salmon at this
season is marked on the cheeks with orange-coloured stripes, which
give it the appearance of a Labrus, and the body partakes of a
golden orange tinge. The females are dark in colour, and are
commonly called black-fish."* An analogous and even greater change
takes place with the Salmo eriox or bull trout; the males of the
char (S. umbla) are likewise at this season rather brighter in
colour than the females.*(2) The colours of the pike (Esox
reticulatus) of the United States, especially of the male, become,
during the breeding-season, exceedingly intense, brilliant, and
iridescent.*(3) Another striking instance out of many is afforded by
the male stickleback (Gasterosteus leiurus), which is described by Mr.
Warington,*(4) as being then "beautiful beyond description." The
back and eyes of the female are simply brown and the belly white.
The eyes of the male, on the other hand, are "of the most splendid
green, having a metallic lustre like the green feathers of some
humming-birds. The throat and belly are of a bright crimson, the
back of an ashy-green, and the whole fish appears as though it were
somewhat translucent and glowed with an internal incandescence." After
the breeding-season these colours all change, the throat and belly
become of a paler red, the back more green, and the glowing tints
subside.
* Yarrell, History of British Fishes, vol. ii., 1836, pp. 10, 12,
35.
*(2) W. Thompson, in Annals and Magazine of Natural History, vol.
vi., 1841, p. 440.
*(3) The American Agriculturalist, 1868, p. 100.
*(4) Annals and Mag. of Nat. Hist., Oct., 1852.
With respect to the courtship of fishes, other cases have been
observed since the first edition of this book appeared, besides that
already given of the stickleback. Mr. W. S. Kent says that the male of
the Labrus mixtus, which, as we have seen, differs in colour from
the female, makes "a deep hollow in the sand of the tank, and then
endeavours in the most persuasive manner to induce a female of the
same species to share it with him, swimming backwards and forwards
between her and the completed nest, and plainly exhibiting the
greatest anxiety for her to follow." The males of Cantharus lineatus
become, during the breeding-season, of deep leaden-black; they then
retire from the shoal, and excavate a hollow as a nest. "Each male now
mounts vigilant guard over his respective hollow, and vigorously
attacks and drives away any other fish of the same sex. Towards his
companions of the opposite sex his conduct is far different; many of
the latter are now distended with spawn, and these he endeavours by
all the means in his power to lure singly to his prepared hollow,
and there to deposit the myriad ova with which they are laden, which
he then protects and guards with the greatest care."*
* Nature, May, 1873, p. 25.
A more striking case of courtship, as well as of display, by the
males of a Chinese Macropus has been given by M. Carbonnier, who
carefully observed these fishes under confinement.* The males are most
beautifully coloured, more so than the females. During the
breeding-season they contend for the possession of the females; and,
in the act of courtship, expand their fins, which are spotted and
ornamented with brightly coloured rays, in the same manner,
according to M. Carbonnier, as the peacock. They then also bound about
the females with much vivacity, and appear by "l'etalage de leurs
vives couleurs chercher a attirer l'attention des femelles, lesquelles
ne paraissaient indifferentes a ce manege, elles nageaient avec une
molle lenteur vers les males et semblaient se complaire dans leur
voisinage." After the male has won his bride, he makes a little disc
of froth by blowing air and mucus out of his mouth. He then collects
the fertilised ova, dropped by the female, in his mouth; and this
caused M. Carbonnier much alarm, as he thought that they were going to
be devoured. But the male soon deposits them in the disc of froth,
afterwards guarding them, repairing the froth, and taking care of
the young when hatched. I mention these particulars because, as we
shall presently see, there are fishes, the males of which hatch
their eggs in their mouths; and those who do not believe in the
principle of gradual evolution might ask how could such a habit have
originated; but the difficulty is much diminished when we know that
there are fishes which thus collect and carry the eggs; for if delayed
by any cause in depositing them, the habit of hatching them in their
mouths might have been acquired.
* Bulletin de la Societe d'Acclimation, Paris, July, 1869, and Jan.,
1870.
To return to our more immediate subject. The case stands thus:
female fishes, as far as I can learn, never willingly spawn except
in the presence of the males; and the males never fertilise the ova
except in the presence of the females. The males fight for the
possession of the females. In many species, the males whilst young
resemble the females in colour; but when adult become much more
brilliant, and retain their colours throughout life. In other
species the males become brighter than the females and otherwise
more highly ornamented, only during the season of love. The males
sedulously court the females, and in one case, as we have seen, take
pains in displaying their beauty before them. Can it be believed
that they would thus act to no purpose during their courtship? And
this would be the case, unless the females exert some choice and
select those males which please or excite them most. If the female
exerts such choice, all the above facts on the ornamentation of the
males become at once intelligible by the aid of sexual selection.
We have next to inquire whether this view of the bright colours of
certain male fishes having been acquired through sexual selection can,
through the law of the equal transmission of characters to both sexes,
be extended to those groups in which the males and females are
brilliant in the same, or nearly the same degree and manner. In such a
genus as Labrus, which includes some of the most splendid fishes in
the world- for instance, the peacock Labrus (L. pavo), described,*
with pardonable exaggeration, as formed of polished scales of gold,
encrusting lapis-lazuli, rubies, sapphires, emeralds, and amethysts-
we may, with much probability, accept this belief; for we have seen
that the sexes in at least one species of the genus differ greatly
in colour. With some fishes, as with many of the lowest animals,
splendid colours may be the direct result of the nature of their
tissues and of the surrounding conditions, without the aid of
selection of any kind. The gold-fish (Cyprinus auratus), judging
from the analogy of the golden variety of the common carp, is
perhaps a case in point, as it may owe its splendid colours to a
single abrupt variation, due to the conditions to which this fish
has been subjected under confinement. It is, however, more probable
that these colours have been intensified through artificial selection,
as this species has been carefully bred in China from a remote
period.*(2) Under natural conditions it does not seem probable that
beings so highly organised as fishes, and which live under such
complex relations, should become brilliantly coloured without
suffering some evil or receiving some benefit from so great a
change, and consequently without the intervention of natural
selection.
* Bory de Saint Vincent, in Dict. Class. d'Hist. Nat., tom. ix.,
1826, p. 151.
*(2) Owing to some remarks on this subject, made in my work On the
Variation of Animals under Domestication, Mr. W. F. Mayers (Chinese
Notes and Queries, Aug., 1868, p. 123) has searched the ancient
Chinese encyclopedias. He finds that gold-fish were first reared in
confinement during the Sung Dynasty, which commenced A.D. 960. In
the year 1129 these fishes abounded. In another place it is said
that since the year 1548 there has been "produced at Hangchow a
variety called the fire-fish, from its intensely red colour. It is
universally admired, and there is not a household where it is not
cultivated, in rivalry as to its colour, and as a source of profit."
What, then, are we to conclude in regard to the many fishes, both
sexes of which are splendidly coloured? Mr. Wallace* believes that the
species which frequent reefs, where corals and other brightly-coloured
organisms abound, are brightly coloured in order to escape detection
by their enemies; but according to my recollection they were thus
rendered highly conspicuous. In the fresh-waters of the tropics
there are no brilliantly-coloured corals or other organisms for the
fishes to resemble; yet many species in the Amazons are beautifully
coloured, and many of the carnivorous Cyprinidae in India are
ornamented with "bright longitudinal lines of various tints."*(2)
Mr. M'Clelland, in describing these fishes, goes so far as to
suppose that "the peculiar brilliancy of their colours" serves as "a
better mark for king-fishers, terns, and other birds which are
destined to keep the number of these fishes in check"; but at the
present day few naturalists will admit that any animal has been made
conspicuous as an aid to its own destruction. It is possible that
certain fishes may have been rendered conspicuous in order to warn
birds and beasts of prey that they were unpalatable, as explained when
treating of caterpillars; but it is not, I believe, known that any
fish, at least any fresh-water fish, is rejected from being
distasteful to fish-devouring animals. On the whole, the most probable
view in regard to the fishes, of which both sexes are brilliantly
coloured, is that their colours were acquired by the males as a sexual
ornament, and were transferred equally, or nearly so, to the other
sex.
* Westminster Review, July, 1867, p. 7.
*(2) "Indian Cyprinidae," by Mr. M'Clelland, Asiatic Researches,
vol. xix., part ii., 1839, p. 230.
We have now to consider whether, when the male differs in a marked
manner from the female in colour or in other ornaments, he alone has
been modified, the variations being inherited by his male offspring
alone; or whether the female has been specially modified and
rendered inconspicuous for the sake of protection, such
modifications being inherited only by the females. It is impossible to
doubt that colour has been gained by many fishes as a protection: no
one can examine the speckled upper surface of a flounder, and overlook
its resemblance to the sandy bed of the sea on which it lives. Certain
fishes, moreover, can through the action of the nervous system
change their colours in adaptation to surrounding objects, and that
within a short time.* One of the most striking instances ever recorded
of an animal being protected by its colour (as far as it can be judged
of in preserved specimens), as well as by its form, is that given by
Dr. Gunther*(2) of a pipe-fish, which, with its reddish streaming
filaments, is hardly distinguishable from the sea-weed to which it
clings with its prehensile tail. But the question now under
consideration is whether the females alone have been modified for this
object. We can see that one sex will not be modified through natural
selection for the sake of protection more than the other, supposing
both to vary, unless one sex is exposed for a longer period to danger,
or has less power of escaping from such danger than the other; and
it does not appear that with fishes the sexes differ in these
respects. As far as there is any difference, the males, from being
generally smaller and from wandering more about, are exposed to
greater danger than the females; and yet, when the sexes differ, the
males are almost always the more conspicuously coloured. The ova are
fertilised immediately after being deposited; and when this process
lasts for several days, as in the case of the salmon,*(3) the
female, during the whole time, is attended by the male. After the
ova are fertilised they are, in most cases, left unprotected by both
parents, so that the males and females, as far as oviposition is
concerned, are equally exposed to danger, and both are equally
important for the production of fertile ova; consequently the more
or less brightly-coloured individuals of either sex would be equally
liable to be destroyed or preserved, and both would have an equal
influence on the colours of their offspring.
* G. Pouchet, L'Institut., Nov. 1, 1871, p. 134.
*(2) Proc. Zoolog. Soc., 1865, p. 327, pls. xiv. and xv.
*(3) Yarrell, British Fishes, vol. ii., p. 11.
Certain fishes belonging to several families, make nests, and some
of them take care of their young when hatched. Both sexes of the
bright-coloured Crenilabrus massa and melops work together in building
their nests with seaweed, shells, &c.* But the males of certain fishes
do all the work, and afterward take exclusive charge of the young.
This is the case with the dull-coloured gobies,*(2) in which the sexes
are not known to differ in colour, and likewise with the
sticklebacks (Gasterosteus), in which the males become brilliantly
coloured during the spawning season. The male of the smooth-tailed
stickleback (G. leiurus) performs the duties of a nurse with exemplary
care and vigilance during a long time, and is continually employed
in gently leading back the young to the nest, when they stray too far.
He courageously drives away all enemies including the females of his
own species. It would indeed be no small relief to the male, if the
female, after depositing her eggs, were immediately devoured by some
enemy, for he is forced incessantly to drive her from the nest.*(3)
* According to the observations of M. Gerbe; see Gunther's Record of
Zoolog. Literature, 1865, p. 194.
*(2) Cuvier, Regne Animal, vol. ii., 1829, p. 242.
*(3) See Mr. Warington's most interesting description of the
habits of the Gasterosteus leiurus in Annals and Magazine of Nat.
History, November, 1855.
The males of certain other fishes inhabiting South America and
Ceylon, belonging to two distinct Orders, have the extraordinary habit
of hatching within their mouths, or branchial cavities, the eggs
laid by the females.* I am informed by Professor Agassiz that the
males of the Amazonian species which follow this habit, "not only
are generally brighter than the females, but the difference is greater
at the spawning-season than at any other time." The species of
Geophagus act in the same manner; and in this genus, a conspicuous
protuberance becomes developed on the forehead of the males during the
breeding-season. With the various species of chromids, as Professor
Agassiz likewise informs me, sexual differences in colour may be
observed, "whether they lay their eggs in the water among aquatic
plants, or deposit them in holes, leaving them to come out without
further care, or build shallow nests in the river mud, over which they
sit, as our Pomotis does. It ought also to be observed that these
sitters are among the brightest species in their respective
families; for instance, Hygrogonus is bright green, with large black
ocelli, encircled with the most brilliant red." Whether with all the
species of chromids it is the male alone which sits on the eggs is not
known. It is, however, manifest that the fact of the eggs being
protected or unprotected by the parents, has had little or no
influence on the differences in colour between the sexes. It is
further manifest, in all the cases in which the males take exclusive
charge of the nests and young, that the destruction of the
brighter-coloured males would be far more influential on the character
of the race, than the destruction of the brighter-coloured females;
for the death of the male during the period of incubation or nursing
would entail the death of the young, so that they could not inherit
his peculiarities; yet, in many of these very cases the males are more
conspicuously coloured than the females.
* Prof. Wyman, in Proc. Boston Soc. of Nat. Hist., Sept. 15, 1857.
Also Prof. Turner, in Journal of Anatomy and Physiology, Nov. 1, 1866,
p. 78. Dr. Gunther has likewise described other cases.
In most of the Lophobranchii (pipe-fish, Hippocampi, &c.) the
males have either marsupial sacks or hemispherical depressions on
the abdomen, in which the ova laid by the female are hatched. The
males also shew great attachment to their young.* The sexes do not
commonly differ much in colour; but Dr. Gunther believes that the male
Hippocampi are rather brighter than the females. The genus
Solenostoma, however, offers a curious exceptional case,*(2) for the
female is much more vividly-coloured and spotted than the male, and
she alone has a marsupial sack and hatches the eggs; so that the
female of Solenostoma differs from all the other Lophobranchii in this
latter respect, and from almost all other fishes, in being more
brightly-coloured than the male. It is improbable that this remarkable
double inversion of character in the female should be an accidental
coincidence. As the males of several fishes, which take exclusive
charge of the eggs and young, are more brightly coloured than the
females, and as here the female Solenostoma takes the same charge
and is brighter than the male, it might be argued that the conspicuous
colours of that sex which is the more important of the two for the
welfare of the offspring, must be in some manner protective. But
from the large number of fishes, of which the males are either
permanently or periodically brighter than the females, but whose
life is not at all more important for the welfare of the species
than that of the female, this view can hardly be maintained. When we
treat of birds we shall meet with analogous cases, where there has
been a complete inversion of the usual attributes of the two sexes,
and we shall then give what appears to be the probable explanation,
namely, that the males have selected the more attractive females,
instead of the latter having selected, in accordance with the usual
rule throughout the animal kingdom, the more attractive males.
* Yarrell, History of British Fishes, vol. ii., 1836, pp. 329, 338.
*(2) Dr. Gunther, since publishing an account of this species in The
Fishes of Zanzibar, by Col. Playfair, 1866, p. 137, has re-examined
the specimens, and has given me the above information.
On the whole we may conclude, that with most fishes, in which the
sexes differ in colour or in other ornamental characters, the males
originally varied, with their variations transmitted to the same
sex, and accumulated through sexual selection by attracting or
exciting the females. In many cases, however, such characters have
been transferred, either partially or completely, to the females. In
other cases, again, both sexes have been coloured alike for the sake
of protection; but in no instance does it appear that the female alone
has had her colours or other characters specially modified for this
latter purpose.
The last point which need be noticed is that fishes are known to
make various noises, some of which are described as being musical. Dr.
Dufosse, who has especially attended to this subject, says that the
sounds are voluntarily produced in several ways by different fishes:
by the friction of the pharyngeal bones- by the vibration of certain
muscles attached to the swim bladder, which serves as a resounding
board- and by the vibration of the intrinsic muscles of the swim
bladder. By this latter means the Trigla produces pure and
long-drawn sounds which range over nearly an octave. But the most
interesting case for us is that of two species of Ophidium, in which
the males alone are provided with a sound-producing apparatus,
consisting of small movable bones, with proper muscles, in
connection with the swim bladder.* The drumming of the Umbrinas in the
European seas is said to be audible from a depth of twenty fathoms;
and the fishermen of Rochelle assert "that the males alone make the
noise during the spawning-time; and that it is possible by imitating
it, to take them without bait."*(2) From this statement, and more
especially from the case of Ophidium, it is almost certain that in
this, the lowest class of the Vertebrata, as with so many insects
and spiders, sound-producing instruments have, at least in some cases,
been developed through sexual selection, as a means for bringing the
sexes together.
* Comptes-Rendus, tom. xlvi., 1858, p. 353; tom. xlvii., 1858, p.
916; tom. liv., 1862, p. 393. The noise made by the Umbrinas
(Sciaena aquila), is said by some authors to be more like that of a
flute or organ, than drumming: Dr. Zouteveen, in the Dutch translation
of this work (vol. ii., p. 36), gives some further particulars on
the sounds made by fishes.
*(2) The Rev. C. Kingsley, in Nature, May, 1870, p. 40.
AMPHIBIANS.
URODELA.- I will begin with the tailed amphibians. The sexes of
salamanders or newts often differ much both in colour and structure.
In some species prehensile claws are developed on the fore-legs of the
males during the breeding-season: and at this season in the male
Triton palmipes the hind-feet are provided with a swimming-web,
which is almost completely absorbed during the winter; so that their
feet then resemble those of the female.* This structure no doubt
aids the male in his eager search and pursuit of the female. Whilst
courting her he rapidly vibrates the end of his tail. With our
common newts (Triton punctatus and cristatus) a deep, much indented
crest is developed along the back and tail of the male during the
breeding-season, which disappears during the winter. Mr. St. George
Mivart informs me that it is not furnished with muscles, and therefore
cannot be used for locomotion. As during the season of courtship it
becomes edged with bright colours, there can hardly be a doubt that it
is a masculine ornament. In many species the body presents strongly
contrasted, though lurid tints, and these become more vivid during the
breeding-season. The male, for instance, of our common little newt
(Triton punctatus) is "brownish-grey above, passing into yellow
beneath, which in the spring becomes a rich bright orange, marked
everywhere with round dark spots." The edge of the crest also is
then tipped with bright red or violet. The female is usually of a
yellowish-brown colour with scattered brown dots, and the lower
surface is often quite plain.*(2) The young are obscurely tinted.
The ova are fertilised during the act of deposition, and are not
subsequently tended by either parent. We may therefore conclude that
the males have acquired their strongly-marked colours and ornamental
appendages through sexual selection; these being transmitted either to
the male offspring alone, or to both sexes.
* Bell, History of British Reptiles, 2nd ed., 1849, pp. 156-159.
*(2) Bell, History of British Reptiles, 2nd ed., 1849, pp. 146, 151.
ANURA or BATRACHIA.- With many frogs and toads the colours evidently
serve as a protection, such as the bright green tints of tree frogs
and the obscure mottled shades of many terrestrial species. The most
conspicuously-coloured toad which I ever saw, the Phryniscus
nigricans,* had the whole upper surface of the body as black as ink,
with the soles of the feet and parts of the abdomen spotted with the
brightest vermilion. It crawled about the bare sandy or open grassy
plains of La Plata under a scorching sun, and could not fail to
catch the eye of every passing creature. These colours are probably
beneficial by making this animal known to all birds of prey as a
nauseous mouthful.
* Zoology of the Voyage of the Beagle, 1843. Bell, ibid., p. 49.
In Nicaragua there is a little frog "dressed in a bright livery of
red and blue" which does not conceal itself like most other species,
but hops about during the daytime, and Mr. Belt says* that as soon
as he saw its happy sense of security, he felt sure that it was
uneatable. After several trials he succeeded in tempting a young
duck to snatch up a young one, but it was instantly rejected; and
the duck "went about jerking its head, as if trying to throw off
some unpleasant taste."
* The Naturalist in Nicaragua, 1874, p. 321.
With respect to sexual differences of colour, Dr. Gunther does not
know of any striking instance either with frogs or toads; yet he can
often distinguish the male from the female by the tints of the
former being a little more intense. Nor does he know of any striking
difference in external structure between the sexes, excepting the
prominences which become developed during the breeding-season on the
front legs of the male, by which he is enabled to hold the female.* It
is surprising that these animals have not acquired more
strongly-marked sexual characters; for though cold-blooded their
passions are strong. Dr. Gunther informs me that he has several
times found an unfortunate female toad dead and smothered from
having been so closely embraced by three or four males. Frogs have
been observed by Professor Hoffman in Giessen fighting all day long
during the breeding-season, and with so much violence that one had its
body ripped open.
* The male alone of the Bufo sikimmensis (Dr. Anderson, Proc.
Zoolog. Soc., 1871, p. 204) has two plate-like callosities on the
thorax and certain rugosities on the fingers, which perhaps subserve
the same end as the above-mentioned prominences.
Frogs and toads offer one interesting sexual difference, namely,
in the musical powers possessed by the males; but to speak of music,
when applied to the discordant and overwhelming sounds emitted by male
bullfrogs and some other species, seems, according to our taste, a
singularly inappropriate expression. Nevertheless, certain frogs
sing in a decidedly pleasing manner. Near Rio Janeiro I used often
to sit in the evening to listen to a number of little Hylae, perched
on blades of grass close to the water, which sent forth sweet chirping
notes in harmony. The various sounds are emitted chiefly by the
males during the breeding-season, as in the case of the croaking of
our common frog.* In accordance with this fact the vocal organs of the
males are more highly-developed than those of the females. In some
genera the males alone are provided with sacs which open into the
larynx.*(2) For instance, in the edible frog (Rana esculenta) "the
sacs are peculiar to the males, and become, when filled with air in
the act of croaking, large globular bladders, standing out one on each
side of the head, near the corners of the mouth." The croak of the
male is thus rendered exceedingly powerful; whilst that of the
female is only a slight groaning noise.*(3) In the several genera of
the family the vocal organs differ considerably in structure, and
their development in all cases may be attributed to sexual selection.
* Bell, History British Reptiles, 1849, p. 93.
*(2) J. Bishop, in Todd's Cyclopaedia of Anatomy and Physiology,
vol. iv., p. 1503.
*(3) Bell, ibid., pp. 112-114.
REPTILES.
CHELONIA.- Tortoises and turtles do not offer well-marked sexual
differences. In some species, the tail of the male is longer than that
of the female. In some, the plastron or lower surface of the shell
of the male is slightly concave in relation to the back of the female.
The male of the mud-turtle of the United States (Chrysemys picta)
has claws on its front feet twice as long as those of the female;
and these are used when the sexes unite.* With the huge tortoise of
the Galapagos Islands (Testudo nigra) the males are said to grow to
a larger size than the females: during the pairing-season, and at no
other time, the male utters a hoarse bellowing noise, which can be
heard at the distance of more than a hundred yards; the female, on the
other hand, never uses her voice.*(2)
* Mr. C. J. Maynard, the American Naturalist, Dec., 1869, p. 555.
*(2) See my Journal of Researches during the Voyage of the Beagle,
1845, p. 384.
With the Testudo elegans of India, it is said "that the combats of
the males may be heard at some distance, from the noise they produce
in butting against each other."*
* Dr. Gunther, Reptiles of British India, 1864, p. 7.
CROCODILIA.- The sexes apparently do not differ in colour; nor do
I know that the males fight together, though this is probable, for
some kinds make a prodigious display before the females. Bartram*
describes the male alligator as striving to win the female by
splashing and roaring in the midst of a lagoon, "swollen to an
extent ready to burst, with its head and tail lifted up, he springs or
twirls round on the surface of the water, like an Indian chief
rehearsing his feats of war." During the season of love, a musky odour
is emitted by the sub-maxiliary glands of the crocodile, and
pervades their haunts.*(2)
* Travels through Carolina, &c., 1791, p. 128.
*(2) Owen, Anatomy of Vertebrates, vol. i., 1866, p. 615.
OPHIDIA.- Dr. Gunther informs me that the males are always smaller
than the females, and generally have longer and slenderer tails; but
he knows of no other difference in external structure. In regard to
colour, be can almost always distinguish the male from the female,
by his more strongly-pronounced tints; thus the black zigzag band on
the back of the male English viper is more distinctly defined than
in the female. The difference is much plainer in the rattle-snakes
of N. America, the male of which, as the keeper in the Zoological
Gardens shewed me, can at once be distinguished from the female by
having more lurid yellow about its whole body. In S. Africa the
Bucephalus capensis presents an analogous difference, for the female
"is never so fully variegated with yellow on the sides as the
male."* The male of the Indian Dipsas cynodon, on the other hand, is
blackish-brown, with the belly partly black, whilst the female is
reddish or yellowish-olive, with the belly either uniform yellowish or
marbled with black. In the Tragops dispar of the same country the male
is bright green, and the female bronze-coloured.*(2) No doubt the
colours of some snakes are protective, as shewn by the green tints
of tree-snakes, and the various mottled shades of the species which
live in sandy places; but it is doubtful whether the colours of many
kinds, for instance of the common English snake and viper, serve to
conceal them; and this is still more doubtful with the many foreign
species which are coloured with extreme elegance. The colours of
certain species are very different in the adult and young states.*(3)
* Sir Andrew Smith, Zoology of S. Africa: Reptilia, 1849, pl. x.
*(2) Dr. A. Gunther, "Reptiles of British India," Ray Soc., 1864,
pp. 304, 308.
*(3) Dr. Stoliczka, Journal of Asiatic Society of Bengal., vol.
xxxix, 1870, pp. 205, 211.
During the breeding-season the anal scentglands of snakes are in
active function;* and so it is with the same glands in lizards, and as
we have seen with the submaxiliary glands of crocodiles. As the
males of most animals search for the females, these odoriferous glands
probably serve to excite or charm the female, rather than to guide her
to the spot where the male may be found. Male snakes, though appearing
so sluggish, are amorous; for many have been observed crowding round
the same female, and even round her dead body. They are not known to
fight together from rivalry. Their intellectual powers are higher than
might have been anticipated. In the Zoological Gardens they soon learn
not to strike at the iron bar with which their cages are cleaned;
and Dr. Keen of Philadelphia informs me that some snakes which he kept
learned after four or five times to avoid a noose, with which they
were at first easily caught. An excellent observer in Ceylon, Mr. E.
Layard, saw*(2) a cobra thrust its head through a narrow hole and
swallow a toad. "With this encumbrance be could not withdraw
himself; finding this, he reluctantly disgorged the precious morsel,
which began to move off; this was too much for snake philosophy to
bear, and the toad was again seized, and again was the snake, after
violent efforts to escape, compelled to part with its prey. This time,
however, a lesson had been learnt, and the toad was seized by one leg,
withdrawn, and then swallowed in triumph."
* Owen, Anatomy of Vertebrates, vol. i., 1866, p. 615.
*(2) "Rambles in Ceylon," in Annals and Magazine of Natural History,
2nd series, vol. ix., 1852, p. 333.
The keeper in the Zoological Gardens is positive that certain
snakes, for instance Crotalus and Python, distinguish him from all
other persons. Cobras kept together in the same cage apparently feel
some attachment towards each other.*
* Dr. Gunther, Reptiles of British India, 1864, p. 340.
It does not, however, follow because snakes have some reasoning
power, strong passions and mutual affection, that they should likewise
be endowed with sufficient taste to admire brilliant colours in
their partners, so as to lead to the adornment of the species
through sexual selection. Nevertheless, it is difficult to account
in any other manner for the extreme beauty of certain species; for
instance, of the coral-snakes of S. America, which are of a rich red
with black and yellow transverse bands. I well remember how much
surprise I felt at the beauty of the first coral-snake which I saw
gliding across a path in Brazil. Snakes coloured in this peculiar
manner, as Mr. Wallace states on the authority of Dr. Gunther,* are
found nowhere else in the world except in S. America, and here no less
than four genera occur. One of these, Elaps, is venomous; a second and
widely-distinct genus is doubtfully venomous, and the two others are
quite harmless. The species belonging to these distinct genera inhabit
the same districts, and are so like each other that no one "but a
naturalist would distinguish the harmless from the poisonous kinds."
Hence, as Mr. Wallace believes, the innocuous kinds have probably
acquired their colours as a protection, on the principle of imitation;
for they would naturally be thought dangerous by their enemies. The
cause, however, of the bright colours of the venomous Elaps remains to
be explained, and this may perhaps be sexual selection.
* Westminster Review, July 1, 1867, p. 32.
Snakes produce other sounds besides hissing. The deadly Echis
carinata has on its sides some oblique rows of scales of a peculiar
structure with serrated edges; and when this snake is excited these
scales are rubbed against each other, which produces "a curious
prolonged, almost hissing sound."* With respect to the rattling of the
rattle-snake, we have at last some definite information: for Professor
Aughey states,*(2) that on two occasions, being himself unseen, he
watched from a little distance a rattle-snake coiled up with head
erect, which continued to rattle at short intervals for half an
hour: and at last he saw another snake approach, and when they met
they paired. Hence be is satisfied that one of the uses of the
rattle is to bring the sexes together. Unfortunately he did not
ascertain whether it was the male or the female which remained
stationary and called for the other. But it by no means follows from
the above fact that the rattle may not be of use to snakes in other
ways, as a warning to animals which would otherwise attack them. Nor
can I quite disbelieve the several accounts which have appeared of
their thus paralysing their prey with fear. Some other snakes also
make a distinct noise by rapidly vibrating their tails against the
surrounding stalks of plants; and I have myself heard this in the case
of a Trigonocephalus in S. America.
* Dr. Anderson, Proc. Zoolog. Soc., 1871, p. 196.
*(2) The American Naturalist, 1873, p. 85.
LACERTILIA.- The males of some, probably of many kinds of lizards,
fight together from rivalry. Thus the arboreal Anolis cristatellus
of S. America is extremely pugnacious: "During the spring and early
part of the summer, two adult males rarely meet without a contest.
On first seeing one another, they nod their heads up and down three or
four times, and at the same time expanding the frill or pouch
beneath the throat; their eyes glisten with rage, and after waving
their tails from side to side for a few seconds, as if to gather
energy, they dart at each other furiously, rolling over and over,
and holding firmly with their teeth. The conflict generally ends in
one of the combatants losing his tail, which is often devoured by
the victor." The male of this species is considerably larger than
the female;* and this, as far as Dr. Gunther has been able to
ascertain, is the general rule with lizards of all kinds. The male
alone of the Cyrtodactylus rubidus of the Andaman Islands possesses
pre-anal pores; and these pores, judging from analogy, probably
serve to emit an odour.*(2)
* Mr. N. L. Austen kept these animals alive for a considerable time;
see Land and Water, July, 1867, P. 9.
*(2) Stoliczka, Journal of the Asiatic Society of Bengal, vol.
xxxiv., 1870, p. 166.
The sexes often differ greatly in various external characters. The
male of the above-mentioned Anolis is furnished with a crest which
runs along the back and tail, and can be erected at pleasure; but of
this crest the female does not exhibit a trace. In the Indian Cophotis
ceylanica, the female has a dorsal crest, though much less developed
than in the male; and so it is, as Dr. Gunther informs me, with the
females of many iguanas, chameleons, and other lizards. In some
species, however, the crest is equally developed in both sexes, as
in the Iguana tuberculata. In the genus Sitana, the males alone are
furnished with a large throat pouch (see fig. 33), which can be folded
up like a fan, and is coloured blue, black, and red; but these
splendid colours are exhibited only during the pairing-season. The
female does not possess even a rudiment of this appendage. In the
Anolis cristatellus, according to Mr. Austen, the throat pouch,
which is bright red marbled with yellow, is present in the female,
though in a rudimental condition. Again, in certain other lizards,
both sexes are equally well provided with throat pouches. Here we
see with species belonging to the same group, as in so many previous
cases, the same character either confined to the males, or more
largely developed in them than in the females, or again equally
developed in both sexes. The little lizards of the genus Draco,
which glide through the air on their rib-supported parachutes, and
which in the beauty of their colours baffle description, are furnished
with skinny appendages to the throat "like the wattles of gallinaceous
birds." These become erected when the animal is excited. They occur in
both sexes, but are best developed when the male arrives at
maturity, at which age the middle appendage is sometimes twice as long
as the head. Most of the species likewise have a low crest running
along the neck; and this is much more developed in the full-grown
males than in the females or young males.*
* All the foregoing statements and quotations, in regard to
Cophotis, Sitana and Draco, as well as the following facts in regard
to Ceratophora and Chamaeleon, are from Dr. Gunther himself, or from
his magnificent work on the "Reptiles of British India," Ray Soc.,
1864, pp. 122, 130, 135.
A Chinese species is said to live in pairs during the spring; "and
if one is caught, the other falls from the tree to the ground, and
allows itself to be captured with impunity"- I presume from despair.*
* Mr. Swinhoe, Proc. Zoolog. Soc., 1870, p. 240.
There are other and much more remarkable differences between the
sexes of certain lizards. The male of Ceratophora aspera bears on
the extremity of his snout an appendage half as long as the head. It
is cylindrical, covered with scales, flexible, and apparently
capable of erection: in the female it is quite rudimental. In a second
species of the same genus a terminal scale forms a minute horn on
the summit of the flexible appendage; and in a third species (see C.
stoddartii, fig. 34) the whole appendage is converted into a horn,
which is usually of a white colour, but assumes a purplish tint when
the animal is excited. In the adult male of this latter species the
horn is half an inch in length, but it is of quite minute size in
the female and in the young. These appendages, as Dr. Gunther has
remarked to me, may be compared with the combs of gallinaceous
birds, and apparently serve as ornaments.
In the genus Chamaeleon we come to the acme of difference between
the sexes. The upper part of the skull of the male C. bifurcus (see
fig. 35), an inhabitant of Madagascar, is produced into two great,
solid, bony projections, covered with scales like the rest of the
head; and of this wonderful modification of structure the female
exhibits only a rudiment. Again, in Chamaeleo owenii (see fig. 36),
from the west coast of Africa, the male bears on his snout and
forehead three curious horns, of which the female has not a trace.
These horns consist of an excrescence of bone covered with a smooth
sheath, forming part of the general integuments of the body, so that
they are identical in structure with those of a bull, goat, or other
sheath-horned ruminant. Although the three horns differ so much in
appearance from the two great prolongations of the skull in C.
bifurcus, we can hardly doubt that they serve the same general purpose
in the economy of these two animals. The first conjecture, which
will occur to every one, is that they are used by the males for
fighting together; and as these animals are very quarrelsome,* this is
probably a correct view. Mr. T. W. Wood also informs me that he once
watched two individuals of C. pumilus fighting violently on the branch
of a tree; they flung their heads about and tried to bite each
other; they then rested for a time and afterwards continued their
battle.
* Dr. Buchholz, Monatsbericht K. Preuss. Akad., Jan., 1874, p. 78.
With many lizards the sexes differ slightly in colour, the tints and
stripes of the males being brighter and more distinctly defined than
in the females. This, for instance, is the case with the above
Cophotis and with the Acanthodactylus capensis of S. Africa. In a
Cordylus of the latter country, the male is either much redder or
greener than the female. In the Indian Calotes nigrilabris there is
a still greater difference; the lips also of the male are black,
whilst those of the female are green. In our common little
viviparous lizard (Zootoca vivipara) "the under side of the body and
base of the tail in the male are bright orange, spotted with black; in
the female these parts are pale-greyish-green without spots."* We have
seen that the males alone of Sitana possess a throat-pouch; and this
is splendidly tinted with blue, black, and red. In the Proctotretus
tenuis of Chile the male alone is marked with spots of blue, green,
and coppery-red.*(2) In many cases the males retain the same colours
throughout the year, but in others they become much brighter during
the breeding-season; I may give as an additional instance the
Calotes maria, which at this season has a bright red head, the rest of
the body being green.*(3)
* Bell, History of British Reptiles, 2nd ed., 1849, p. 40.
*(2) For Proctotretus, see Zoology of the Voyage of the Beagle;
Reptiles by Mr. Bell, p. 8. For the lizards of S. Africa, see
Zoology of S. Africa: Reptiles, by Sir Andrew Smith, pls. 25 and 39.
For the Indian Calotes, see Reptiles of British India, by Dr. Gunther,
p. 143.
*(3) Gunther in Proceedings, Zoological Society, 1870, p. 778,
with a coloured figure.
Both sexes of many species are beautifully coloured exactly alike;
and there is no reason to suppose that such colours are protective. No
doubt with the bright green kinds which live in the midst of
vegetation, this colour serves to conceal them; and in N. Patagonia
I saw a lizard (Proctotretus multimaculatus) which, when frightened,
flattened its body, closed its eyes, and then from its mottled tints
was hardly distinguishable from the surrounding sand. But the bright
colours with which so many lizards are ornamented, as well as their
various curious appendages, were probably acquired by the males as
an attraction, and then transmitted either to their male offspring, or
to both sexes. Sexual selection, indeed, seems to have played almost
as important a part with reptiles as with birds; and the less
conspicuous colours of the females in comparison with the males cannot
be accounted for, as Mr. Wallace believes to be the case with birds,
by the greater exposure of the females to danger during incubation.
CHAPTER XIII.
SECONDARY SEXUAL CHARACTERS OF BIRDS.
SECONDARY sexual characters are more diversified and conspicuous
in birds, though not perhaps entailing more important changes of
structure, than in any other class of animals. I shall, therefore,
treat the subject at considerable length. Male birds sometimes, though
rarely, possess special weapons for fighting with each other. They
charm the female by vocal or instrumental music of the most varied
kinds. They are ornamented by all sorts of combs, wattles,
protuberances, horns, air-distended sacks, top-knots, naked shafts,
plumes and lengthened feathers gracefully springing from all parts
of the body. The beak and naked skin about the head, and the feathers,
are often gorgeously coloured. The males sometimes pay their court
by dancing, or by fantastic antics performed either on the ground or
in the air. In one instance, at least, the male emits a musky odour,
which we may suppose serves to charm or excite the female; for that
excellent observer, Mr. Ramsay,* says of the Australian musk-duck
(Biziura lobata) that "the smell which the male emits during the
summer months is confined to that sex, and in some individuals is
retained throughout the year; I have never, even in the
breeding-season, shot a female which had any smell of musk." So
powerful is this odour during the pairing-season, that it can be
detected long before the bird can be seen.*(2) On the whole, birds
appear to be the most aesthetic of all animals, excepting of course
man, and they have nearly the same taste for the beautiful as we have.
This is shown by our enjoyment of the singing of birds, and by our
women, both civilised and savage, decking their heads with borrowed
plumes, and using gems which are hardly more brilliantly coloured than
the naked skin and wattles of certain birds. In man, however, when
cultivated, the sense of beauty is manifestly a far more complex
feeling, and is associated with various intellectual ideas.
* Ibis., vol. iii. (new series), 1867, p. 414.
*(2) Gould, Handbook of the Birds of Australia, 1865, vol. ii., p.
383.
Before treating of the sexual characters with which we are here more
particularly concerned, I may just allude to certain differences
between the sexes which apparently depend on differences in their
habits of life; for such cases, though common in the lower, are rare
in the higher classes. Two humming-birds belonging to the genus
Eustephanus, which inhabit the island of Juan Fernandez, were long
thought to be specifically distinct, but are now known, as Mr. Gould
informs me, to be the male and female of the same species, and they
differ slightly in the form of the beak. In another genus of
humming-birds (Grypus), the beak of the male is serrated along the
margin and hooked at the extremity, thus differing much from that of
the female. In the Neomorpha of New Zealand, there is, as we have
seen, a still wider difference in the form of the beak in relation
to the manner of feeding of the two sexes. Something of the same
kind has been observed with the goldfinch (Carduelis elegans), for I
am assured by Mr. J. Jenner Weir that the bird-catchers can
distinguish the males by their slightly longer beaks. The flocks of
males are often found feeding on the seeds of the teazle (Dipsacus),
which they can reach with their elongated beaks, whilst the females
more commonly feed on the seeds of the betony or Scrophularia. With
a slight difference of this kind as a foundation, we can see how the
beaks of the two sexes might be made to differ greatly through natural
selection. In some of the above cases, however, it is possible that
the beaks of the males may have been first modified in relation to
their contests with other males; and that this afterwards led to
slightly changed habits of life.
Law of Battle.- Almost all male birds are extremely pugnacious,
using their beaks, wings, and legs for fighting together. We see
this every spring with our robins and sparrows. The smallest of all
birds, namely the humming-bird, is one of the most quarrelsome. Mr.
Gosse* describes a battle in which a pair seized hold of each
other's beaks, and whirled round and round, till they almost fell to
the ground; and M. Montes de Oca, in speaking or another genus of
humming-bird, says that two males rarely meet without a fierce
aerial encounter: when kept in cages "their fighting has mostly
ended in the splitting of the tongue of one of the two, which then
surely dies from being unable to feed."*(2) With waders, the males
of the common water-hen (Gallinula chloropus) "when pairing, fight
violently for the females: they stand nearly upright in the water
and strike with their feet." Two were seen to be thus engaged for half
an hour, until one got hold of the head of the other, which would have
been killed had not the observer interfered; the female all the time
looking on as a quiet spectator.*(3) Mr. Blyth informs me that the
males of an allied bird (Gallicrex cristatus) are a third larger
than the females, and are so pugnacious during the breeding- season
that they are kept by the natives of eastern Bengal for the sake of
fighting. Various other birds are kept in India for the same
purpose, for instance, the bulbuls (Pycnonotus hoemorrhous) which
"fight with great spirit."*(4)
* Quoted by Mr. Gould, Introduction to the Trochilidae, 1861, page
29.
*(2) Gould, ibid., p. 52.
*(3) W. Thompson, Natural History of Ireland: Birds, vol. ii., 1850,
p. 327.
*(4) Jerdon, Birds of India, 1863, vol. ii., p. 96.
The polygamous ruff (see Machetes pugnax, fig. 37) is notorious
for his extreme pugnacity; and in the spring, the males, which are
considerably larger than the females, congregate day after day at a
particular spot, where the females propose to lay their eggs. The
fowlers discover these spots by the turf being trampled somewhat bare.
Here they fight very much like game-cocks, seizing each other with
their beaks and striking with their wings. The great ruff of
feathers round the neck is then erected, and according to Col. Montagu
"sweeps the ground as a shield to defend the more tender parts"; and
this is the only instance known to me in the case of birds of any
structure serving as a shield. The ruff of feathers, however, from its
varied and rich colours probably serves in chief part as an
ornament. Like most pugnacious birds, they seem always ready to fight,
and when closely confined, often kill each other; but Montagu observed
that their pugnacity becomes greater during the spring, when the
long feathers on their necks are fully developed; and at this period
the least movement by any one bird provokes a general battle.* Of
the pugnacity of web-footed birds, two instances will suffice: in
Guiana "bloody fights occur during the breeding-season between the
males of the wild musk-duck (Cairina moschata); and where these fights
have occurred the river is covered for some distance with
feathers."*(2) Birds which seem ill-adapted for fighting engage in
fierce conflicts; thus the stronger males of the pelican drive away
the weaker ones, snapping with their huge beaks and giving heavy blows
with their wings. Male snipe fight together, "tugging and pushing each
other with their bills in the most curious manner imaginable." Some
few birds are believed never to fight; this is the case, according
to Audubon, with one of the woodpeckers of the United States (Picu
sauratus), although "the hens are followed by even half a dozen of
their gay suitors."*(3)
* Macgillivray, History of British Birds, vol. iv., 1852, pp.
177-181.
*(2) Sir R. Schomburgk, in Journal of Royal Geographic Society, vol.
xiii., 1843, p. 31.
*(3) Ornithological Biography, vol. i., p. 191. For pelicans and
snipes, see vol. iii., pp. 138, 477.
The males of many birds are larger than the females, and this no
doubt is the result of the advantage gained by the larger and stronger
males over their rivals during many generations. The difference in
size between the two sexes is carried to an extreme point in several
Australian species; thus the male musk-duck (Biziura), and the male
Cincloramphus cruralis (allied to our pipits) are by measurement
actually twice as large as their respective females.* With many
other birds the females are larger than the males; and, as formerly
remarked, the explanation often given, namely, that the females have
most of the work in feeding their young, will not suffice. In some few
cases, as we shall hereafter see, the females apparently have acquired
their greater size and strength for the sake of conquering other
females and obtaining possession of the males.
* Gould, Handbook of Birds of Australia, vol. i., p. 395; vol.
ii., p. 383.
The males of many gallinaceous birds, especially of the polygamous
kinds, are furnished with special weapons for fighting with their
rivals, namely spurs, which can be used with fearful effect. It has
been recorded by a trustworthy writer* that in Derbyshire a kite
struck at a game-hen accompanied by her chickens, when the cock rushed
to the rescue, and drove his spur right through the eye and skull of
the aggressor. The spur was with difficulty drawn from the skull,
and as the kite, though dead, retained his grasp, the two birds were
firmly locked together; but the cock when disentangled was very little
injured. The invincible courage of the game-cock is notorious: a
gentleman who long ago witnessed the brutal scene, told me that a bird
had both its legs broken by some accident in the cockpit, and the
owner laid a wager that if the legs could be spliced so that the
bird could stand upright, he would continue fighting. This was
effected on the spot, and the bird fought with undaunted courage until
he received his death-stroke. In Ceylon a closely allied, wild
species, the Gallus stanleyi, is known to fight desperately "in
defence of his seraglio," so that one of the combatants is
frequently found dead.*(2) An Indian partridge (Ortygornis gularis),
the male of which is furnished with strong and sharp spurs, is so
quarrelsome "that the scars of former fights disfigure the breast of
almost every bird you kill."*(3)
* Mr. Hewitt, in the Poultry Book, by Tegetmeier, 1866, p. 137.
*(2) Layard, Annals and Magazine of Natural History, vol. xiv.,
1854, p. 63.
*(3) Jerdon, Birds of India, vol. iii., p. 574.
The males of almost all gallinaceous birds, even those which are not
furnished with spurs, engage during the breeding- season in fierce
conflicts. The capercailzie and black-cock (Tetrao urogallus and T.
tetrix), which are both polygamists, have regular appointed places,
where during many weeks they congregate in numbers to fight together
and to display their charms before the females. Dr. W. Kovalevsky
informs me that in Russia he has seen the snow all bloody on the
arenas where the capercailzie have fought; and the black-cocks "make
the feathers fly in every direction," when several "engage in a battle
royal." The elder Brehm gives a curious account of the balz, as the
love-dances and love songs of the black-cock are called in Germany.
The bird utters almost continuously the strangest noises: "he holds
his tail up and spreads it out like a fan, he lifts up his head and
neck with all the feathers erect, and stretches his wings from the
body. Then he takes a few jumps in different directions sometimes in a
circle, and presses the under part of his beak so hard against the
ground that the chin feathers are rubbed off. During these movements
he beats his wings and turns round and round. The more ardent he grows
the more lively he becomes, until at last the bird appears like a
frantic creature." At such times the black-cocks are so absorbed
that they become almost blind and deaf, but less so than the
capercailzie: hence bird after bird may be shot on the same spot, or
even caught by the hand. After performing these antics the males begin
to fight: and the same black-cock, in order to prove his strength over
several antagonists, will visit in the course of one morning several
balz places, which remain the same during successive years.*
* Brehm, Illust. Thierleben, 1867, B. iv., s. 351. Some of the
foregoing statements are taken from L. Lloyd, Game Birds of Sweden,
&c., 1867, p. 79.
The peacock with his long train appears more like a dandy than a
warrior, but he sometimes engages in fierce contests: the Rev. W.
Darwin Fox informs me that at some little distance from Chester two
peacocks became so excited whilst fighting, that they flew over the
whole city, still engaged, until they alighted on the top of St.
John's tower.
The spur, in those gallinaceous birds which are thus provided, is
generally single; but Polyplectron (see fig. 51) has two or more on
each leg; and one of the blood-pheasants (Ithaginis cruentus) has been
seen with five spurs. The spurs are generally confined to the male,
being represented by mere knobs or rudiments in the female; but the
females of the Java peacock (Pavo muticus) and, as I am informed by
Mr. Blyth, of the small fire-backed pheasant (Euplocamus
erythropthalmus) possess spurs. In Galloperdix it is usual for the
males to have two spurs, and for the females to have only one on
each leg.* Hence spurs may be considered as a masculine structure,
which has been occasionally more or less transferred to the females.
Like most other secondary sexual characters, the spurs are highly
variable, both in number and development, in the same species.
* Jerdon, Birds of India: on Ithaginis, vol. iii., p. 523; on
Galloperdix, p. 541.
Various birds have spurs on their wings. But the Egyptian goose
(Chenalopex aegyptiacus) has only "bare obtuse knobs," and these
probably shew us the first steps by which true spurs have been
developed in other species. In the spur-winged goose, Plectropterus
gambensis, the males have much larger spurs than the females; and they
use them, as I am informed by Mr. Bartlett, in fighting together, so
that, in this case, the wing-spurs serve as sexual weapons; but
according to Livingstone, they are chiefly used in the defence of
the young. The Palamedea (see fig. 38) is armed with a pair of spurs
on each wing; and these are such formidable weapons that a single blow
has been known to drive a dog howling away. But it does not appear
that the spurs in this case, or in that of some of the spur-winged
rails, are larger in the male than in the female.* In certain plovers,
however, the wing-spurs must be considered as a sexual character. Thus
in the male of our common peewit (Vanellus cristatus) the tubercle
on the shoulder of the wing becomes more prominent during the
breeding-season, and the males fight together. In some species of
Lobivanellus a similar tubercle becomes developed during the
breeding-season "into a short horny spur." In the Australian L.
lobatus both sexes have spurs, but these are much larger in the
males than in the females. In an allied bird, the Hoplopterus armatus,
the spurs do not increase in size during the breeding-season; but
these birds have been seen in Egypt to fight together, in the same
manner as our peewits, by turning suddenly in the air and striking
sideways at each other, sometimes with fatal results. Thus also they
drive away other enemies.*(2)
* For the Egyptian goose, see Macgillivray, British Birds, vol. iv.,
p. 639. For Plectropterus, Livingstone's Travels, p. 254. For
Palamedea, Brehm's Illustriertes Thierleben, B. iv., s. 740. See
also on this bird Azara, Voyages dans l'Amerique merid., tom. iv.,
1809, pp. 179, 253.
*(2) See, on our peewit, Mr. R. Carr in Land and Water, Aug. 8,
1868, p. 46. In regard to Lobivanellus, see Jerdon's Birds of India,
vol. iii., p. 647, and Gould's Handbook of Birds of Australia, vol.
ii., p. 220. For the Hoplopterus, see Mr. Allen in the Ibis., vol. v.,
1863, p. 156.
The season of love is that of battle; but the males of some birds,
as of the game-fowl and ruff, and even the young males of the wild
turkey and grouse,* are ready to fight whenever they meet. The
presence of the female is the teterrima belli causa. The Bengali
baboos make the pretty little males of the amadavat (Estrelda
amandava) fight together by placing three small cages in a row, with a
female in the middle; after a little time the two males are turned
loose, and immediately a desperate battle ensues.*(2) When many
males congregate at the same appointed spot and fight together, as
in the case of grouse and various other birds, they are generally
attended by the females,*(3) which afterwards pair with the victorious
combatants. But in some cases the pairing precedes instead of
succeeding the combat: thus according to Audubon,*(4) several males of
the Virginian goat-sucker (Caprimulgus virgianus) "court, in a
highly entertaining manner the female, and no sooner has she made
her choice, than her approved gives chase to all intruders and
drives them beyond his dominions." Generally the males try to drive
away or kill their rivals before they pair. It does not, however,
appear that the females invariably prefer the victorious males. I have
indeed been assured by Dr. W. Kovalevsky that the female
capercailzie sometimes steals away with a young male who has not dared
to enter the arena with the older cocks, in the same manner as
occasionally happens with the does of the red-deer in Scotland. When
two males contend in presence of a single female, the victor, no
doubt, commonly gains his desire; but some of these battles are caused
by wandering males trying to distract the peace of an already mated
pair.*(5)
* Audubon, Ornithological Biography, vol. ii., p. 492; vol. i.,
pp. 4-13.
*(2) Mr. Blyth, Land and Water, 1867, p. 212.
*(3) Richardson on Tetrao umbellus, Fauna Bor. Amer.: Birds, 1831,
p. 343. L. Lloyd, Game Birds of Sweden, 1867, pp. 22, 79, on the
capercailzie and black-cock. Brehm, however, asserts (Thierleben, B.
iv., s. 352) that in Germany the grey-hens do not generally attend the
Balzen of the black-cocks, but this is an exception to the common
rule; possibly the hens may lie hidden in the surrounding bushes, as
is known to be the case with the grey-hens in Scandinavia, and with
other species in N. America.
*(4) Ornithological Biography, vol. ii., p. 275.
*(5) Brehm, Thierleben, &c., B. iv., 1867, p. 990. Audubon,
Ornithological Biography, vol. ii., p. 492.
Even with the most pugnacious species it is probable that the
pairing does not depend exclusively on the mere strength and courage
of the male; for such males are generally decorated with various
ornaments, which often become more brilliant during the
breeding-season, and which are sedulously displayed before the
females. The males also endeavour to charm or excite their mates by
love-notes, songs, and antics; and the courtship is, in many
instances, a prolonged affair. Hence it is not probable that the
females are indifferent to the charms of the opposite sex, or that
they are invariably compelled to yield to the victorious males. It
is more probable that the females are excited, either before or
after the conflict, by certain males, and thus unconsciously prefer
them. In the case of Tetrao umbellus, a good observer* goes so far
as to believe that the battles of the male "are all a sham,
performed to show themselves to the greatest advantage before the
admiring females who assemble around; for I have never been able to
find a maimed hero, and seldom more than a broken feather." I shall
have to recur to this subject, but I may here add that with the Tetrao
cupido of the United States, about a score of males assemble at a
particular spot, and, strutting about, make the whole air resound with
their extraordinary noises. At the first answer from a female the
males begin to fight furiously, and the weaker give way; but then,
according to Audubon, both the victors and vanquished search for the
female, so that the females must either then exert a choice, or the
battle must be renewed. So, again, with one of the field-starlings
of the United States (Sturnella ludoviciana) the males engage in
fierce conflicts, "but at the sight of a female they all fly after her
as if mad."*(2)
* Land and Water, July 25, 1868, p. 14.
*(2) Audubon's Ornithological Biography; on Tetrao cupido, vol. ii.,
p. 492; on the Sturnus, vol. ii., p. 219.
Vocal and instrumental music.- With birds the voice serves to
express various emotions, such as distress, fear, anger, triumph, or
mere happiness. It is apparently sometimes used to excite terror, as
in the case of the hissing noise made by some nestling-birds.
Audubon*, relates that a night-heron (Ardea nycticorax, Linn.),
which he kept tame, used to hide itself when a cat approached, and
then "suddenly start up uttering one of the most frightful cries,
apparently enjoying the cat's alarm and flight." The common domestic
cock clucks to the hen, and the hen to her chickens, when a dainty
morsel is found. The hen, when she has laid an egg, "repeats the
same note very often, and concludes with the sixth above, which she
holds for a longer time";*(2) and thus she expresses her joy. Some
social birds apparently call to each other for aid; and as they flit
from tree to tree, the flock is kept together by chirp answering
chirp. During the nocturnal migrations of geese and other
water-fowl, sonorous clangs from the van may be heard in the
darkness overhead, answered by clangs in the rear. Certain cries serve
as danger signals, which, as the sportsman knows to his cost, are
understood by the same species and by others. The domestic cock crows,
and the humming-bird chirps, in triumph over a defeated rival. The
true song, however, of most birds and various strange cries are
chiefly uttered during the breeding-season, and serve as a charm, or
merely as a call-note, to the other sex.
* Ornithological Biography, vol. v., p. 601.
*(2) The Hon. Daines Barrington, Philosophical Transactions, 1773,
p. 252.
Naturalists are much divided with respect to the object of the
singing of birds. Few more careful observers ever lived than
Montagu, and he maintained that the "males of songbirds and of many
others do not in general search for the female, but, on the
contrary, their business in the spring is to perch on some conspicuous
spot, breathing out their full and armorous notes, which, by instinct,
the female knows, and repairs to the spot to choose her mate."* Mr.
Jenner Weir informs me that this is certainly the case with the
nightingale. Bechstein, who kept birds during his whole life, asserts,
"that the female canary always chooses the best singer, and that in
a state of nature the female finch selects that male out of a
hundred whose notes please her most."*(2) There can be no doubt that
birds closely attend to each other's song. Mr. Weir has told me of the
case of a bullfinch which had been taught to pipe a German waltz,
and who was so good a performer that he cost ten guineas; when this
bird was first introduced into a room where other birds were kept
and he began to sing, all the others, consisting of about twenty
linnets and canaries, ranged themselves on the nearest side of their
cages, and listened with the greatest interest to the new performer.
Many naturalists believe that the singing of birds is almost
exclusively "the effect of rivalry and emulation," and not for the
sake of charming their mates. This was the opinion of Daines
Barrington and White of Selborne, who both especially attended to this
subject.*(3) Barrington, however, admits that "superiority in song
gives to birds an amazing ascendancy over others, as is well known
to bird-catchers."
* Ornithological Dictionary, 1833, p. 475.
*(2) Naturgeschichte der Stubenvogel, 1840, s. 4. Mr. Harrison
Weir likewise writes to me; "I am informed that the best singing males
generally get a mate first, when they are bred in the same room,"
*(3) Philosophical Transactions, 1773, p. 263. White's Natural
History of Selborne, 1825, vol. i., p. 246.
It is certain that there is an intense degree of rivalry between the
males in their singing. Bird-fanciers match their birds to see which
will sing longest; and I was told by Mr. Yarrell that a first-rate
bird will sometimes sing till he drops down almost dead, or
according to Bechstein,* quite dead from rupturing a vessel in the
lungs. Whatever the cause may be, male birds, as I hear from Mr. Weir,
often die suddenly during the season of song. That the habit of
singing is sometimes quite independent of love is clear, for a
sterile, hybrid canary-bird has been described*(2) as singing whilst
viewing itself in a mirror, and then dashing at its own image; it
likewise attacked with fury a female canary, when put into the same
cage. The jealousy excited by the act of singing is constantly taken
advantage of by bird-catchers; a male in good song, is hidden and
protected, whilst a stuffed bird, surrounded by limed twigs, is
exposed to view. In this manner, as Mr. Weir informs me, a man has
in the course of a single day caught fifty, and in one instance,
seventy, male chaffinches. The power and inclination to sing differ so
greatly with birds that although the price of an ordinary male
chaffinch is only sixpence, Mr. Weir saw one bird for which the
bird-catcher asked three pounds; the test of a really good singer
being that it will continue to sing whilst the cage is swung round the
owner's head.
* Naturgesch. der Stubenvogel, 1840, s. 252.
*(2) Mr. Bold, Zoologist, 1843-44, p. 659.
That male birds should sing from emulation as well as for charming
the female, is not at all incompatible; and it might have been
expected that these two habits would have concurred, like those of
display and pugnacity. Some authors, however, argue that the song of
the male cannot serve to charm the female, because the females of some
few species, such as of the canary, robin, lark, and bullfinch,
especially when in a state of widowhood, as Bechstein remarks, pour
forth fairly melodious strains. In some of these cases the habit of
singing may be in part attributed to the females having been highly
fed and confined,* for this disturbs all the functions connected
with the reproduction of the species. Many instances have already been
given of the partial transference of secondary masculine characters to
the female, so that it is not at all surprising that the females of
some species should possess the power of song. It has also been
argued, that the song of the male cannot serve as a charm, because the
males of certain species, for instance of the robin, sing during the
autumn.*(2) But nothing is more common than for animals to take
pleasure in practising whatever instinct they follow at other times
for some real good. How often do we see birds which fly easily,
gliding and sailing through the air obviously for pleasure? The cat
plays with the captured mouse, and the cormorant with the captured
fish. The weaver-bird (Ploceus), when confined in a cage, amuses
itself by neatly weaving blades of grass between the wires of its
cage. Birds which habitually fight during the breeding-season are
generally ready to fight at all times; and the males of the
capercailzie sometimes hold their Balzen or leks at the usual place of
assemblage during the autumn.*(3) Hence it is not at all surprising
that male birds should continue singing for their own amusement
after the season for courtship is over.
* D. Barrington, Philosophical Transactions, 1773, p. 262.
Bechstein, Stubenvogel, 1840, s. 4.
*(2) This is likewise the case with the water-ouzel; see Mr. Hepburn
in the Zoologist, 1845-46, p. 1068.
*(3) L. Lloyd, Game Birds of Sweden, 1867, p. 25.
As shewn in a previous chapter, singing is to a certain extent an
art, and is much improved by practice. Birds can be taught various
tunes, and even the unmelodious sparrow has learnt to sing like a
linnet. They acquire the song of their foster parents,* and
sometimes that of their neighbours.*(2) All the common songsters
belong to the Order of Insessores, and their vocal organs are much
more complex than those of most other birds; yet it is a singular fact
that some of the Insessores, such as ravens, crows, and magpies,
possess the proper apparatus,*(3) though they never sing, and do not
naturally modulate their voices to any great extent. Hunter
asserts*(4) that with the true songsters the muscles of the larynx are
stronger in the males than in the females; but with this slight
exception there is no difference in the vocal organs of the two sexes,
although the males of most species sing so much better and more
continuously than the females.
* Barrington, ibid., p. 264, Bechstein, ibid., s. 5.
*(2) Dureau de la Malle gives a curious instance (Annales des Sc.
Nat., 3rd series, Zoolog., tom. x., p. 118) of some wild blackbirds in
his garden in Paris, which naturally learnt a republican air from a
caged bird.
*(3) Bishop, in Todd's Cyclopaedia of Anatomy and Physiology, vol.
iv., p. 1496.
*(4) As stated by Barrington in Philosophical Transactions, 1773, p.
262.
It is remarkable that only small birds properly sing. The Australian
genus Menura, however, must be excepted; for the Menura alberti, which
is about the size of a half-grown turkey, not only mocks other
birds, but "its own whistle is exceedingly beautiful and varied."
The males congregate and form "corroborying places," where they
sing, raising and spreading their tails like peacocks, and drooping
their wings.* It is also remarkable that birds which sing well are
rarely decorated with brilliant colours or other ornaments. Of our
British birds, excepting the bullfinch and goldfinch, the best
songsters are plain-coloured. The kingfisher, bee-eater, roller,
hoopoe, wood-peckers, &c., utter harsh cries; and the brilliant
birds of the tropics are hardly ever songsters.*(2) Hence bright
colours and the power of song seem to replace each other. We can
perceive that if the plumage did not vary in brightness, or if
bright colours were dangerous to the species, other means would be
employed to charm the females; and melody of voice offers one such
means.
* Gould, Handbook of the Birds of Australia, vol. i., 1865, pp.
308-310. See also Mr. T. W. Wood in the Student, April, 1870, p. 125.
*(2) See remarks to this effect in Gould's Introduction to the
Trochilidae,, 1861, p. 22.
In some birds the vocal organs differ greatly in the two sexes. In
the Tetrao cupido (see fig. 39) the male has two bare, orange-coloured
sacks, one on each side of the neck; and these are largely inflated
when the male, during the breeding-season, makes his curious hollow
sound, audible at a great distance. Audubon proved that the sound
was intimately connected with this apparatus (which reminds us of
the air-sacks on each side of the mouth of certain male frogs), for he
found that the sound was much diminished when one of the sacks of a
tame bird was pricked, and when both were pricked it was altogether
stopped. The female has "a somewhat similar, though smaller naked
space of skin on the neck; but this is not capable of inflation."* The
male of another kind of grouse (Tetrao urophasianus), whilst
courting the female, has his "bare yellow oesophagus inflated to a
prodigious size, fully half as large as the body"; and he then
utters various grating, deep, hollow tones. With his neck-feathers
erect, his wings lowered, and buzzing on the ground, and his long
pointed tail spread out like a fan, he displays a variety of grotesque
attitudes. The oesophagus of the female is not in any way
remarkable.*(2)
* The Sportsman and Naturalist in Canada, by Major W. Ross King,
1866, pp. 144-146. Mr. T. W. Wood gives in the Student (April, 1870,
p. 116) an excellent account of the attitude and habits of this bird
during its courtship. He states that the ear-tufts or neck-plumes
are erected, so that they meet over the crown of the head. See his
drawing, fig. 39.
*(2) Richardson, Fauna Bor. Americana: Birds, 1831, p. 359. Audubon,
ibid., vol. iv., p. 507.
It seems now well made out that the great throat pouch of the
European male bustard (Otis tarda), and of at least four other
species, does not, as was formerly supposed, serve to hold water,
but is connected with the utterance during the breeding-season of a
peculiar sound resembling "oak."* A crow-like bird inhabiting South
America (see Cephalopterus ornatus, fig. 40) is called the
umbrella-bird, from its immense top knot, formed of bare white
quills surmounted by dark-blue plumes, which it can elevate into a
great dome no less than five inches in diameter, covering the whole
head. This bird has on its neck a long, thin, cylindrical fleshy
appendage, which is thickly clothed with scale-like blue feathers.
It probably serves in part as an ornament, but likewise as a
resounding apparatus; for Mr. Bates found that it is connected "with
an unusual development of the trachea and vocal organs." It is dilated
when the bird utters its singularly deep, loud and long sustained
fluty note. The head-crest and neck-appendage are rudimentary in the
female.*(2)
* The following papers have been lately written on this subject:
Prof. A. Newton, in the Ibis, 1862, p. 107; Dr. Cullen, ibid., 1865,
p. 145; Mr. Flower, in Proc. Zool. Soc., 1865, p. 747; and Dr.
Murie, in Proc. Zool. Soc., 1868, p. 471. In this latter paper an
excellent figure is given of the male Australian bustard in full
display with the sack distended. It is a singular fact that the sack
is not developed in all the males of the same species.
*(2) Bates, The Naturalist on the Amazons, 1863, vol. ii., p. 284;
Wallace, in Proceedings, Zoological Society, 1850, p. 206. A new
species, with a still larger neck-appendage (C. penduliger), has
lately been discovered, see Ibis, vol. i., p. 457.
The vocal organs of various web-footed and wading birds are
extraordinarily complex, and differ to a certain extent in the two
sexes. In some cases the trachea is convoluted, like a French horn,
and is deeply embedded in the sternum. In the wild swan (Cygnus ferus)
it is more deeply embedded in the adult male than in the adult
female or young male. In the male Merganser the enlarged portion of
the trachea is furnished with an additional pair of muscles.* In one
of the ducks, however, namely Anas punctata, the bony enlargement is
only a little more developed in the male than in the female.*(2) But
the meaning of these differences in the trachea of the two sexes of
the Anatidae is not understood; for the male is not always the more
vociferous; thus with the common duck, the male hisses, whilst the
female utters a loud quack.*(3) In both sexes of one of the cranes
(Grus virgo) the trachea penetrates the sternum, but presents "certain
sexual modifications." In the male of the black stork there is also
a well-marked sexual difference in the length and curvature of the
bronchi.*(4) Highly important structures have, therefore, in these
cases been modified according to sex.
* Bishop, in Todd's Cyclopaedia of Anatomy and Physiology, vol. iv.,
p. 1499.
*(2) Prof. Newton, Proc. Zoolog. Soc., 1871, p. 651.
*(3) The spoonbill (Platalea) has its trachea convoluted into a
figure of eight, and yet this bird (Jerdon, Birds of India, vol. iii.,
p. 763) is mute but Mr. Blyth informs me that the convolutions are not
constantly present, so that perhaps they are now tending towards
abortion.
*(4) Elements of Comparative Anatomy, by R. Wagner, Eng.
translat., 1845, p. 111. With respect to the swan as given above,
Yarrell's History of British Birds, 2nd edition, 1845, vol. iii., p.
193.
It is often difficult to conjecture whether the many strange cries
and notes uttered by male birds during the breeding-season serve as
a charm or merely as a call to the female. The soft cooing of the
turtle-dove and of many pigeons, it may be presumed, pleases the
female. When the female of the wild turkey utters her call in the
morning, the male answers by a note which differs from the gobling
noise made, when with erected feathers, rustling wings and distended
wattles, he puffs and struts before her.* The spel of the black-cock
certainly serves as a call to the female, for it has been known to
bring four or five females from a distance to a male under
confinement; but as the black-cock continues his spel for hours during
successive days, and in the case of the capercailzie "with an agony of
passion," we are led to suppose that the females which are present are
thus charmed.*(2) The voice of the common rook is known to alter
during the breeding-season, and is therefore in some way sexual.*(3)
But what shall we say about the harsh screams of, for instance, some
kinds of macaws; have these birds as bad taste for musical sounds as
they apparently have for colour, judging by the inharmonious
contrast of their bright yellow and blue plumage? It is indeed
possible that without any advantage being thus gained, the loud voices
of many male birds may be the result of the inherited effects of the
continued use of their vocal organs when excited by the strong
passions of love, jealousy and rage; but to this point we shall
recur when we treat of quadrupeds.
* C. L. Bonaparte, quoted in the Naturalist Library: Birds, vol.
xiv., p. 126.
*(2) L. Lloyd, The Game Birds of Sweden, &c., 1867, pp. 22, 81.
*(3) Jenner, Philosophical Transactions, 1824, p. 20.
We have as yet spoken only of the voice, but the males of various
birds practise, during their courtship, what may be called
instrumental music. Peacocks and birds of paradise rattle their quills
together. Turkey-cocks scrape their wings against the ground, and some
kinds of grouse thus produce a buzzing sound. Another North American
grouse, the Tetrao umbellus, when with his tail erect, his ruffs
displayed, "he shows off his finery to the females, who lie hid in the
neighbourhood," drums by rapidly striking his wings together above his
back, according to Mr. R. Haymond, and not, as Audubon thought, by
striking them against his sides. The sound thus produced is compared
by some to distant thunder, and by others to the quick roll of a drum.
The female never drums, "but flies directly to the place where the
male is thus engaged." The male of the Kalij-pheasant, in the
Himalayas, often makes a singular drumming noise with his wings, not
unlike the sound produced by shaking a stiff piece of cloth." On the
west coast of Africa the little black-weavers (Ploceus?) congregate in
a small party on the bushes round a small open space, and sing and
glide through the air with quivering wings, "which make a rapid
whirring sound like a child's rattle." One bird after another thus
performs for hours together, but only during the courting-season. At
this season, and at no other time, the males of certain night-jars
(Caprimulgus) make a strange booming noise with their wings. The
various species of woodpeckers strike a sonorous branch with their
beaks, with so rapid a vibratory movement that "the head appears to be
in two places at once." The sound thus produced is audible at a
considerable distance but cannot be described; and I feel sure that
its source would never be conjectured by any one hearing it for the
first time. As this jarring sound is made chiefly during the
breeding-season, it has been considered as a love-song; but it is
perhaps more strictly a love-call. The female, when driven from her
nest, has been observed thus to call her mate, who answered in the
same manner and soon appeared. Lastly, the male hoopoe (Upupa epops)
combines vocal and instrumental music; for during the
breeding-season this bird, as Mr. Swinhoe observed, first draws in
air, and then taps the end of its beak perpendicularly down against
a stone or the trunk of a tree, "when the breath being forced down the
tubular bill produces the correct sound." If the beak is not thus
struck against some object, the sound is quite different. Air is at
the same time swallowed, and the oesophagus thus becomes much swollen;
and this probably acts as a resonator, not only with the hoopoe, but
with pigeons and other birds.*
* For the foregoing facts see, on birds of paradise, Brehm,
Thierleben, B. iii., s. 325. On grouse, Richardson, Fauna Bor.
Americ.: Birds, pp. 343 and 359; Major W. Ross King, The Sportsman
in Canada, 1866, p. 156; Mr. Haymond, in Prof. Cox's Geol. Survey of
Indiana, p. 227; Audubon, American Ornitholog. Biograph., vol. i.,
p. 216. On the Kalij-pheasant, Jerdon, Birds of India, vol. iii., p.
533. On the weavers, Livingstone's Expedition to the Zambesi, 1865, p.
425. On woodpeckers, Macgillivray, Hist. of British Birds, vol.
iii., 1840, pp. 84, 88, 89, and 95. On the hoopoe, Mr. Swinhoe, in
Proc. Zoolog. Soc., June 23, 1863 and 1871, p. 348. On the
night-jar, Audubon, ibid., vol. ii., p. 255, and American
Naturalist, 1873, p. 672. The English night-jar likewise makes in
the spring a curious noise during its rapid flight.
In the foregoing cases sounds are made by the aid of structures
already present and otherwise necessary; but in the following cases
certain feathers have been specially modified for the express
purpose of producing sounds. The drumming, bleating, neighing, or
thundering noise (as expressed by different observers) made by the
common snipe (Scolopax gallinago) must have surprised every one who
has ever heard it. This bird, during the pairing-season, flies to
"perhaps a thousand feet in height," and after zig-zagging about for a
time descends to the earth in a curved line, with outspread tail and
quivering pinions, and surprising velocity. The sound is emitted
only during this rapid descent. No one was able to explain the cause
until M. Meves observed that on each side of the tail the outer
feathers are peculiarly formed (see fig. 41), having a stiff
sabre-shaped shaft with the oblique barbs of unusual length, the outer
webs being strongly bound together. He found that by blowing on
these feathers, or by fastening them to a long thin stick and waving
them rapidly through the air, he could reproduce the drumming noise
made by the living bird. Both sexes are furnished with these feathers,
but they are generally larger in the male than in the female, and emit
a deeper note. In some species, as in S. frenata (see fig. 42), four
feathers, and in S. javensis (see fig. 43), no less than eight on each
side of the tail are greatly modified. Different tones are emitted
by the feathers of the different species when waved through the air;
and the Scolopax wilsonii of the United States makes a switching noise
whilst descending rapidly to the earth.*
* See M. Meves' interesting paper in Proc. Zool. Soc., 1858, p. 199.
For the habits of the snipe, Macgillivray, History of British Birds,
vol. iv., p. 371. For the American snipe, Capt. Blakiston, Ibis,
vol. v., 1863, p. 131.
In the male of the Chamaepetes unicolor (a large gallinaceous bird
of America), the first primary wing-feather is arched towards the
tip and is much more attenuated than in the female. In an allied bird,
the Penelope nigra, Mr. Salvin observed a male, which, whilst it
flew downwards "with outstretched wings, gave forth a kind of crashing
rushing noise," like the falling of a tree.* The male alone of one
of the Indian bustards (Sypheotides auritus) has its primary
wing-feathers greatly acuminated; and the male of an allied species is
known to make a humming noise whilst courting the female.*(2) In a
widely different group of birds, namely humming-birds, the males alone
of certain kinds have either the shafts of their primary wing-feathers
broadly dilated, or the webs abruptly excised towards the extremity.
The male, for instance, of Selasphorus platycercus, when adult, has
the first primary wing-feather (see fig. 44), thus excised. Whilst
flying from flower to flower he makes "a shrill, almost whistling
noise";*(3) but it did not appear to Mr. Salvin that the noise was
intentionally made.
* Mr. Salvin, in Proceedings, Zoological Society, 1867, p. 160. I am
much indebted to this distinguished ornithologist for sketches of
the feathers of the Chamaepetes, and for other information.
*(2) Jerdon, Birds of India, vol. iii., pp. 618, 621.
*(3) Gould, Introduction to the Trochilidae, 1861, p. 49. Salvin,
Proceedings, Zoological Society, 1867, p. 160.
Lastly, in several species of a sub-genus of Pipra or manakin, or
manakin, the males, as described by Mr. Sclater, have their
secondary wing-feathers modified in a still more remarkable manner. In
the brilliantly-coloured P. deliciosa the first three secondaries
are thick-stemmed and curved towards the body; in the fourth and fifth
(see fig. 45, a) the change is greater; and in the sixth and seventh
(b, c) the shaft "is thickened to an extraordinary degree, forming a
solid horny lump." The barbs also are greatly changed in shape, in
comparison with the corresponding feathers (d, e, f) in the female.
Even the bones of the wing, which support these singular feathers in
the male, are said by Mr. Fraser to be much thickened. These little
birds make an extraordinary noise, the first "sharp note being not
unlike the crack of a whip."*
* Sclater, in Proceedings, Zoological Society, 1860, p. 90, and in
Ibis, vol. iv., 1862, p. 175. Also Salvin, in Ibis, 1860, p. 37.
The diversity of the sounds, both vocal and instrumental, made by
the males of many birds during the breeding-season, and the
diversity of the means for producing such sounds, are highly
remarkable. We thus gain a high idea of their importance for sexual
purposes, and are reminded of the conclusion arrived at as to insects.
It is not difficult to imagine the steps by which the notes of a bird,
primarily used as a mere call or for some other purpose, might have
been improved into a melodious love song. In the case of the
modified feathers, by which the drumming, whistling, or roaring noises
are produced, we know that some birds during their courtship
flutter, shake, or rattle their unmodified feathers together; and if
the females were led to select the best performers, the males which
possessed the strongest or thickest, or most attenuated feathers,
situated on any part of the body, would be the most successful; and
thus by slow degrees the feathers might be modified to almost any
extent. The females, of course, would not notice each slight
successive alteration in shape, but only the sounds thus produced.
It is a curious fact that in the same class of animals, sounds so
different as the drumming of the snipe's tail, the tapping of the
woodpecker's beak, the harsh trumpet-like cry of certain water-fowl,
the cooing of the turtle-dove, and the song of the nightingale, should
all be pleasing to the females of the several species. But we must not
judge of the tastes of distinct species by a uniform standard; nor
must we judge by the standard of man's taste. Even with man, we should
remember what discordant noises, the beating of tom-toms and the
shrill notes of reeds, please the ears of savages. Sir S. Baker
remarks,* that "as the stomach of the Arab prefers the raw meat and
reeking liver taken hot from the animal, so does his ear prefer his
equally coarse and discordant music to all other."
* The Nile Tributaries of Abyssinia, 1867, p. 203.
Love Antics and Dances.- The curious love gestures of some birds
have already been incidentally noticed; so that little need here be
added. In Northern America large numbers of a grouse, the Tetrao
phasianellus, meet every morning during the breeding-season on a
selected level spot, and here they run round and round in a circle
of about fifteen or twenty feet in diameter, so that the ground is
worn quite bare, like a fairy-ring. In these partridge-dances, as they
are called by the hunters, the birds assume the strangest attitudes,
and run round, some to the left and some to the right. Audubon
describes the males of a heron (Ardea herodias) as walking about on
their long legs with great dignity before the females, bidding
defiance to their rivals. With one of the disgusting
carrion-vultures (Cathartes jota) the same naturalist states that "the
gesticulations and parade of the males at the beginning of the
love-season are extremely ludicrous." Certain birds perform their
love-antics on the wing, as we have seen with the black African
weaver, instead of on the ground. During the spring our little
white-throat (Sylvia cinerea) often rises a few feet or yards in the
air above some bush, and "flutters with a fitful and fantastic motion,
singing all the while, and then drops to its perch." The great English
bustard throws himself into indescribably odd attitudes whilst
courting the female, as has been figured by Wolf. An allied Indian
bustard (Otis bengalensis) at such times "rises perpendicularly into
the air with a hurried flapping of his wings, raising his crest and
puffing out the feathers of his neck and breast, and then drops to the
ground"; he repeats this manoeuvre several times, at the same time
humming in a peculiar tone. Such females as happen to be near "obey
this saltatory summons," and when they approach he trails his wings
and spreads his tail like a turkey-cock.*
* For Tetrao phasianellus, see Richardson, Fauna, Bor. Americana, p.
361, and for further particulars, Capt. Blakiston, Ibis, 1863, p. 125.
For the Cathartes and Ardea, Audubon, Ornithological Biography, vol.
ii., p. 51, and vol. iii., p. 89. On the white-throat, Macgillivray,
History of British Birds, vol. ii., p. 354. On the Indian bustard,
Jerdon, Birds of India, vol. iii., p. 618.
But the most curious case is afforded by three allied genera of
Australian birds, the famous bower-birds,- no doubt the co-descendants
of some ancient species which first acquired the strange instinct of
constructing bowers for performing their love-antics. The bowers
(see fig. 46), which, as we shall hereafter see, are decorated with
feathers, shells, bones, and leaves, are built on the ground for the
sole purpose of courtship, for their nests are formed in trees. Both
sexes assist in the erection of the bowers, but the male is the
principal workman. So strong is this instinct that it is practised
under confinement, and Mr. Strange has described* the habits of some
satin bower-birds which he kept in an aviary in New South Wales. "At
times the male will chase the female all over the aviary, then go to
the bower, pick up a gay feather or a large leaf, utter a curious kind
of note, set all his feathers erect, run round the bower and become so
excited that his eyes appear ready to start from his bead; he
continues opening first one wing then the other, uttering a low,
whistling note, and, like the domestic cock, seems to be picking up
something from the ground, until at last the female goes gently
towards him." Captain Stokes has described the habits and
"play-houses" of another species, the great bower-bird, which was seen
"amusing itself by flying backwards and forwards, taking a shell
alternately from each side, and carrying it through the archway in its
mouth." These curious creations, formed solely as halls of assemblage,
where both sexes amuse themselves and pay their court, must cost the
birds much labor. The bower, for instance, of the fawn-breasted
species, is nearly four feet in length, eighteen inches in height, and
is raised on a thick platform of sticks.
* Gould, Handbook to the Birds of Australia, vol. i., pp. 444,
449, 455. The bower of the satin bower-bird may be seen in the
Zoological Society's Gardens, Regent's Park.
Decoration.- I will first discuss the cases in which the males are
ornamented either exclusively or in a much higher degree than the
females, and in a succeeding chapter those in which both sexes are
equally ornamented, and finally the rare cases in which the female
is somewhat more brightly-coloured than the male. As with the
artificial ornaments used by savage and civilised men, so with the
natural ornaments of birds, the head is the chief seat of decoration.*
The ornaments, as mentioned at the commencement of this chapter, are
wonderfully diversified. The plumes on the front or back of the head
consist of variously-shaped feathers, sometimes capable of erection or
expansion, by which their beautiful colours are fully displayed.
Elegant ear-tufts (see fig. 39, ante) are occasionally present. The
head is sometimes covered with velvety down, as with the pheasant;
or is naked and vividly coloured. The throat, also, is sometimes
ornamented with a beard, wattles, or caruncles. Such appendages are
generally brightly-coloured, and no doubt serve as ornaments, though
not always ornamental in our eyes; for whilst the male is in the act
of courting the female, they often swell and assume vivid tints, as in
the male turkey. At such times the fleshy appendages about the head of
the male tragopan pheasant (Ceriornis temminckii) swell into a large
lappet on the throat and into two horns, one on each side of the
splendid topknot; and these are then coloured of the most intense blue
which I have ever beheld.*(2) The African hornbill (Bucorax
abyssinicus) inflates the scarlet bladder-like wattle on its neck, and
with its wings drooping and tail expanded "makes quite a grand
appearance."*(3) Even the iris of the eye is sometimes more
brightly-coloured in the male than in the female; and this is
frequently the case with the beak, for instance, in our common
blackbird. In Buceros corrugatus, the whole beak and immense casque
are coloured more conspicuously in the male than in the female; and
"the oblique grooves upon the sides of the lower mandible are peculiar
to the male sex."*(4)
* See remarks to this effect, on the "Feeling of Beauty among
Animals," by Mr. J. Shaw, in the Athenaeum, Nov. 24, 1866, p. 681.
*(2) See Dr. Murie's account with coloured figures in Proceedings,
Zoological Society, 1872, p. 730.
*(3) Mr. Monteiro, Ibis, vol. iv., 1862, p. 339.
*(4) Land and Water, 1868, p. 217.
The head, again, often supports fleshy appendages, filaments, and
solid protuberances. These, if not common to both sexes, are always
confined to the males. The solid protuberances have been described
in detail by Dr. W. Marshall,* who shews that they are formed either
of cancellated bone coated with skin, or of dermal and other
tissues. With mammals true horns are always supported on the frontal
bones, but with birds various bones have been modified for this
purpose; and in species of the same group the protuberances may have
cores of bone, or be quite destitute of them, with intermediate
gradations connecting these two extremes. Hence, as Dr. Marshall
justly remarks, variations of the most different kinds have served for
the development through sexual selection of these ornamental
appendages. Elongated feathers or plumes spring from almost every part
of the body. The feathers on the throat and breast are sometimes
developed into beautiful ruffs and collars. The tail-feathers are
frequently increased in length; as we see in the tail-coverts of the
peacock, and in the tail itself of the Argus pheasant. With the
peacock even the bones of the tail have been modified to support the
heavy tail-coverts.*(2) The body of the Argus is not larger than
that of a fowl; yet the length from the end of the beak to the
extremity of the tail is no less than five feet three inches,*(3)
and that of the beautifully ocellated secondary wing-feathers nearly
three feet. In a small African night-jar (Cosmetornis vexillarius) one
of the primary wing-feathers, during the breeding-season, attains a
length of twenty-six inches, whilst the bird itself is only ten inches
in length. In another closely-allied genus of night-jars, the shafts
of the elongated wing-feathers are naked, except at the extremity,
where there is a disc.*(4) Again, in another genus of night-jars,
the tail-feathers are even still more prodigiously developed. In
general the feathers of the tail are more often elongated than those
of the wings, as any great elongation of the latter impedes flight. We
thus see that in closely-allied birds ornaments of the same kind
have been gained by the males through the development of widely
different feathers.
* "Uber die Schadelhocker," Niederland. Archiv. fur Zoologie, B. i.,
Heft 2, 1872.
*(2) Dr. W. Marshall, "Uber den Vogelschwanz," ibid., B. i., Heft 2,
1872.
*(3) Jardine's Naturalist Library: Birds, vol. xiv., p. 166.
*(4) Sclater, in the Ibis, vol. vi., 1864, p. 114; Livingstone,
Expedition to the Zambesi, 1865, p. 66.
It is a curious fact that the feathers of species belonging to
very distinct groups have been modified in almost exactly the same
peculiar manner. Thus the wing-feathers in one of the
above-mentioned night-jars are bare along the shaft, and terminate
in a disc; or are, as they are sometimes called, spoon or
racket-shaped. Feathers of this kind occur in the tail of a motmot
(Eumomota superciliaris), of a king-fisher, finch, humming-bird,
parrot, several Indian drongos (Dicrurus and Edolius, in one of
which the disc stands vertically), and in the tail of certain birds of
paradise. In these latter birds, similar feathers, beautifully
ocellated, ornament the head, as is likewise the case with some
gallinaceous birds. In an Indian bustard (Sypheotides auritus) the
feathers forming the ear-tufts, which are about four inches in length,
also terminate in discs.* It is a most singular fact that the motmots,
as Mr. Salvin has clearly shown,*(2) give to their tail feathers the
racket-shape by biting off the barbs, and, further, that this
continued mutilation has produced a certain amount of inherited
effect.
* Jerdon, Birds of India, vol. iii., p. 620.
*(2) Proceedings, Zoological Society, 1873, p. 429.
Again, the barbs of the feathers in various widely-distinct birds
are filamentous or plumose, as with some herons, ibises, birds of
paradise, and Gallinaceae. In other cases the barbs disappear, leaving
the shafts bare from end to end; and these in the tail of the
Paradisea apoda attain a length of thirty-four inches:* in P.
Papuana (see fig. 47) they are much shorter and thin. Smaller feathers
when thus denuded appear like bristles, as on the breast of the
turkey-cock. As any fleeting fashion in dress comes to be admired by
man, so with birds a change of almost any kind in the structure or
colouring of the feathers in the male appears to have been admired
by the female. The fact of the feathers in widely distinct groups
having been modified in an analogous manner no doubt depends primarily
on all the feathers having nearly the same structure and manner of
development, and consequently tending to vary in the same manner. We
often see a tendency to analogous variability in the plumage of our
domestic breeds belonging to distinct species. Thus top-knots have
appeared in several species. In an extinct variety of the turkey,
the top-knot consisted of bare quills surmounted with plumes of
down, so that they somewhat resembled the racket-shaped feathers above
described. In certain breeds of the pigeon and fowl the feathers are
plumose, with some tendency in the shafts to be naked. In the
Sebastopol goose the scapular feathers are greatly elongated,
curled, or even spirally twisted, with the margins plumose.*(2)
* Wallace, in Annals and Magazine of Natural History, vol. xx.,
1857, p. 416, and in his Malay Archipelago, vol. ii., 1869, p. 390.
*(2) See my work on The Variation of Animals and Plants under
Domestication, vol. i., pp. 289, 293.
In regard to colour, hardly anything need here be said, for every
one knows how splendid are the tints of many birds, and how
harmoniously they are combined. The colours are often metallic and
iridescent. Circular spots are sometimes surrounded by one or more
differently shaded zones, and are thus converted into ocelli. Nor need
much be said on the wonderful difference between the sexes of many
birds. The common peacock offers a striking instance. Female birds
of paradise are obscurely coloured and destitute of all ornaments,
whilst the males are probably the most highly decorated of all
birds, and in so many different ways that they must be seen to be
appreciated. The elongated and golden-orange plumes which spring
from beneath the wings of the Paradisea apoda, when vertically erected
and made to vibrate, are described as forming a sort of halo, in the
centre of which the head "looks like a little emerald sun with its
rays formed by the two plumes."* In another most beautiful species the
head is bald, "and of a rich cobalt blue, crossed by several lines
of black velvety feathers."*(2)
* Quoted from M. de Lafresnaye in Annals and Mag. of Natural
History, vol. xiii., 1854, p. 157: see also Mr. Wallace's much
fuller account in vol. xx., 1857, p. 412, and in his The Malay
Archipelago.
*(2) Wallace, The Malay Archipelago, vol. ii., 1869, p. 405.
Male humming-birds (see figs. 48 and 49) almost vie with birds of
paradise in their beauty, as every one will admit who has seen Mr.
Gould's splendid volumes, or his rich collection. It is very
remarkable in how many different ways these birds are ornamented.
Almost every part of their plumage has been taken advantage of, and
modified; and the modifications have been carried, as Mr. Gould shewed
me, to a wonderful extreme in some species belonging to nearly every
sub-group. Such cases are curiously like those which we see in our
fancy breeds, reared by man for the sake of ornament; certain
individuals originally varied in one character, and other
individuals of the same species in other characters; and these have
been seized on by man and much augmented- as shewn by the tail of
the fantail-pigeon, the hood of the jacobin, the beak and wattle of
the carrier, and so forth. The sole difference between these cases
is that in the one, the result is due to man's selection, whilst in
the other, as with humming-birds, birds of paradise, &c., it is due to
the selection by the females of the more beautiful males.
I will mention only one other bird, remarkable from the extreme
contrast in colour between the sexes, namely the famous bell-bird
(Chasmorhynchus niveus) of S. America, the note of which can be
distinguished at the distance of nearly three miles, and astonishes
every one when first hearing it. The male is pure white, whilst the
female is dusky-green; and white is a very rare colour in
terrestrial species of moderate size and inoffensive habits. The male,
also, as described by Waterton, has a spiral tube, nearly three inches
in length, which rises from the base of the beak. It is jet-black,
dotted over with minute downy feathers. This tube can be inflated with
air, through a communication with the palate; and when not inflated
hangs down on one side. The genus consists of four species, the
males of which are very distinct, whils 
