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Vestigial Structures

As a high-school freshman in 1950, I took my first biology class. I remember studying about vestigial organs. Fascinating I thought, and it sure made sense considering it fit so well into the concept of biological evolution. Evolution, as explained by my biology teacher—and clearly stated in my textbook—was obviously true. At that time, so many years ago, I did not realize that there were those who disagreed.

Most people are astonished to discover my first introduction to evolution was several years earlier in Sunday school class. Amazing but true! New York City’s prestigious Riverside Church enlisted Sunday school teachers from the nearby Union Theological Seminary, at that time under the influence of notable Unitarian educator Sophia Lyon Fahs. Sunday school teachers showed us a homemade chart of the “evolutionary ladder,” and explained how all life evolved from simple organisms into current animal and plant survivors.

Subsequent studies in college and graduate school, and readings in science and nature followed, but the term “vestigial” seldom came up again. Why should it? It was an established scientific concept and certainly not as controversial as many other developments in science, such as stem cell research… Or, so I thought.

Vestigial structures, I recently discovered, do not exist. At least that is what I was told by a group of folks from Campus Crusade for Christ. “No such thing,” they swore. “Can’t exist. All organ structures were created by God and have not changed in 6,000 years,” which they believed is the age of the earth and universe.

I hardly knew how to respond. It was as if I had encountered a group of “flat earthers.” Where does one start? How might I explain to them that vestigial structures, such as our remnant and nonfunctional ear muscles, are the leftovers from a time long ago when our ancestors could actually turn their ears to better detect sounds of danger or pleasure?

The Campus Crusaders would have none of it. If vestigial organs really existed, they argued, then evolution was true. And, if evolution was true then the earth really was billions of years old as science tells us—not the six thousand they claim the bible tells them. According to them the belief in vestigial structures is a contradiction of God’s word as written in the bible. No wonder they were adamant about it. Case closed. Science is valid only if it agrees with scripture and invalid if it does not.

I decided to take on an impossible task, mostly for fun. I attempted to persuade the Campus Crusaders through e-mails that vestigial structures really do exist. Perhaps one of the crusaders had an inquisitive mind; perhaps one of them had doubts; perhaps one of them would “see the light,” a term they so often fall back on.

I was surprised to find abundant and long drawn-out arguments against the existence of vestigial structures on many religious websites, the most thorough of which is found at Answers in Genesis. What was going on? Why was there so much effort by fundamentalist believers, Christian, Jewish, and Muslim to discredit a little known scientific fact?

In my e-mails to them I presented the facts, instances where structures and organs evolved from one shape and function to another or to none at all. I hardly knew where to begin because examples of vestigial structures are so numerous.

The scientific definition of vestigial has, like much of science, changed over the last century. It currently states that any structure, organ, physiological or metabolic function that has changed (evolved) over time by diminishing in size or function so as to become functionless, or near functionless compared to its original use, is vestigial. I understand that to someone who has never formally studied science and scientific methodology, it can seem complicated. However, the aforementioned vestigial ear muscles are a simple concept that most people can understand. Humans have four diminished and unused muscles around each ear. Yes, I have heard of a few talented kids who can wiggle their ears, and by doing so they unknowingly attest to the ancient use of the muscles. Today, these pitiful muscle remnants are just a few of many vestigial structures found in animals and plants.

Other vestigial organs are as follows:

1) Whales have hipbones and remnants of legs buried deep within their bodies. These structures are the remnants of functional hips and legs of ancient whale ancestors that lived on land before they returned to the sea. Fossil evidence is abundant.

2) Humans have canine teeth, the remnants of predatory weapons used to kill and tear the flesh of prey. Although canine teeth are still useful, they are no longer used as they once were.

3) Most humans have wisdom teeth. As the shape of the human face changed over many millennia, the upper and lower jaw reduced in size. Wisdom teeth, which were once a priority for grinding the heavy cellulose diet of our ancient ancestors, are currently being crowded out by the reduction in size of the mandible. They continue to be used for grinding cellulose but at a far diminished level.

4) Humans have an appendix that once was a larger functional digestive sack used to digest the high cellulose diet of human ancestors. The appendix retains some usefulness in children as a storage place for digestive bacteria and immune cells, but no longer functions as a digestive organ.

5) Some snakes, like whales, have vestigial hipbones and legs, remnants of useful structures found in their quadruped ancestors.

6) Blind cave fish and deep-sea residents have vestigial eyes under a layer of skin and scales. The complete darkness of their habitats made normal eyes useless and a survival disadvantage.

7) Dandelions have vestigial pollen and other asexual plants have vestigial sex organs carried over from a time when their plant ancestors reproduced sexually.

8) Humans have vestigial skin muscles that cause goose bumps and stand hair erect, a carryover from the time human ancestors had full body hair.

9) Flightless birds, such as penguins and ostriches, have vestigial flight wings. Their wings are currently used for swimming and balance while running but are vestigial for flying.

10) Humans have vestigial coccyx bones, remnants of our ancient ancestors’ tails. Occasionally human babies are born with actual tails.

11) Humans have a vestigial eyelid, the tiny plica semilunaris, which has reduced in size and is located at the medial corner of the eye.

12) Humans have vestigial genes that once enabled us to manufacture Vitamin C. Humans and guinea pigs no longer have that ability and must ingest Vitamin C to prevent scurvy.

13) Thousands of beetle species have vestigial, nonfunctional wings hidden under a hard shell. The ancestors of those beetles could fly at one time.

I could go on but I think most people get the idea. Vestigial structures do exist and are evidence of evolutionary change over time. Unfortunately my Campus Crusade acquaintances did not accept the scientific facts. I was disappointed but not surprised.

Answers in Genesis disparages the concept of vestigial structures by pointing out that the definition of “vestigial” has changed over the years, and therefore suggests that the new, revised definition should not be believed any more than the old definition. Once right, always right. Change is unacceptable.

They are correct about its changing nature. What they do not appreciate is that as new information is uncovered, science must change to remain valid and useful to us in the modern world. If science did not evolve, humanity would still be handicapped with Dark-age science and medicine. Fortunately (or unfortunately as the case may be), most moderate Christians, Jews, and Muslims are able to retain their religious beliefs in the light of new molecular, genetic, cosmologic, and fossil evolutionary evidence. It was a serious blow to religion when it was discovered the earth was not the center of the universe and was not flat. I urged my Campus Crusade friends to moderate their beliefs in accordance to the overwhelming scientific evidence of biological evolution. After all, the human brain is not yet vestigial, at least for most of us.

Vestigial Organs
Vestigial organs, what can they be?
What they were once I cannot see.
What will they become I’ll never know
How they change and slowly grow.
Thinking about them can be a strain
If you have one for a brain.