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The Chin Enigma


Writing at The Conversation, biologist Ben Garrod explains, “These ‘useless’ quirks of evolution are actually evidence for the theory.” Well, they would have to be, wouldnt they? Everything is evidence of evolution, a scientific hypothesis that can’t be falsified. Garrod considers sexual selection, supposed vestigial organs, and evolutionary spandrels, concluding with the human chin.

There’s a photo of a man with a strong chin, accompanying Dr. Garrod’s discussion of the chin as a unique feature of our anatomy, with no clear evolutionary explanation. Under the photo is the caption, “What separates us from the beasts.” Of course writers at online magazines don’t generally compose their own photo captions. An editor almost certainly wrote this one. But it testifies nicely to a common cultural myth — that not much “separates us from the beasts.” Not intellect, not art, not soul, not science, just…the chin. A picture is worth a thousand words, they say, and sometimes the caption under a picture is, too.

A Chance, Unexpected Byproduct

Garrod concludes:

One genuine exception is something that defines our species as modern human beings: the chin. No other animals, or even extinct human relatives like Neanderthals, have one. As human diets changed, the bones and muscles in our jaws became smaller so we didn’t waste energy on them but we were left with a protruding bone at the bottom of the face. And no one has come up with a wholly convincing reason why.

Although the chin throws a spandrel in the works, there is nearly always a reason or, at least, an explanation for the myriad traits we see across biology. A better understanding of these evolutionary obscurities paves the way for a deeper understanding of the complex factors and drivers which influence the natural world around us.

The Biology of the Baroque

Biologist Ann Gauger has addressed the chin enigma here at Evolution News, pointing out that talk of spandrels — which are chance, unexpected “by-product[s] from some other functional adaptation” — overlooks the obvious explanation, which is aesthetic:

Perhaps it does reveal something important about being human. Perhaps no adaptive explanation for chins exists, because they aren’t adaptations — they arise from aesthetic considerations. Without a chin there would be no delicate curve of the neck in Swan Lake, no graceful oval shape to the face, no balance or proportion in portraits. It’s not just that we are used to chins. We respond to proportion in all things, be it architecture, landscapes, or the spiral petals of a rose. The chin balances the face.

An actual swan doesn’t have a chin, but a woman does, and that makes quite a bit of difference. To train yourself not to see this is remarkable. A scientific theory that on principle refuses to acknowledge the obvious is an achievement, among so many others, of which only humans are capable.

By the way, noticing the chin is only the beginning. There are many, many features of biology that do not permit explanations in terms of “functional adaptation.” See The Biology of the Baroque, which features the work of another Discovery Institute biologist, Michael Denton:

Photo: Molly Wagner, Swan Lake, by KCBalletMedia [CC BY 2.0], via Wikimedia Commons.