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Why do only humans have chins?

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Mental region (chin).png
Mental region (chin)/Mikael Häggström, CC

The Atlantic says no one knows why. Apparently, it’s not for chewing, finding mates, speaking, or taking punches.

[Anthropologist James] Pampush doubts that chins are adaptations at all. He thinks it’s more likely that they are spandrels—incidental features that have no benefits in themselves, but are byproducts of evolution acting upon something else.

A different explanation portrays the chin as a bit of the jaw that got left behind while the rest shrunk back. As early humans started cooking and processing our food, we made fewer demands upon our teeth, which started shrinking as a result. They gradually retracted into the face, while the part of the lower jaw that held them did not (or, at least, did so more slowly). Hence: chin.

Stephen Jay Gould and Richard Lewontin, who coined the concept of evolutionary spandrels, liked this hypothesis. So does Nathan Holton from the University of Iowa, who studies facial evolution. “It seems that the appearance of the chin itself is probably related to patterns of facial reduction in humans during the Pleistocene,” he says. “In this sense, understanding why faces became smaller is important to explaining why we have chins.”

“But why did the lower border of the jaw also not shrink?” Pampush asks. “What happened that left that last little bit sticking out?” This is the problem with spandrel hypotheses more generally: They’re often very hard to test. More.

Yes, we were just thinking that. Hard to test… Interestingly, Pampush notes, “The chin is one of these rare phenomena in evolutionary biology that really exposes the deep philosophical differences between researchers in the field.” Say more.

That’s overdue for discussion, it seems.

See also: Why do we need less sleep than chimps?

Rethinking evolution mechanisms

and

Human origins: The war of trivial explanations

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One theory:

13 Replies to “Why do only humans have chins?

  1. 1
    Robert Byers says:

    I didn’t know we only had chins. So apes have no chins eh.
    The mans chin is a sign of handsomeness they say. So it must be a part of the most accurate symmetry .
    In making us God may simply of done it this way.
    Or after the flood when we NEWLY started eating meat this might of affected the chin, just like the wisdom teeth probably, .
    it does seem to me we were meant to be bigger and atrophied everywhere.
    So the chin is not what it should be but is more then we would suspect it should be.

  2. 2
    GaryGaulin says:

    Our chins are tiny in comparison to elephants, some fish, and likely other animals:

    http://thefreaky.net/weird-ani.....-man-fish/

    Only humans having chins turned out to be another myth.

  3. 3
    GaryGaulin says:

    Robert, according to the inference in question: if it is true that only elephants have “trunks” and such giant chins then they better qualify as examples of divine special creation. They even have a larger brain than we do and only seem dumb because we cannot yet fully understand their language.

  4. 4
    Robert Byers says:

    GaryGaulin
    Brains to me are only memory machines. Brain size is irrelevant to thinking ability.
    They are as dumb as sheep or bugs. Your language point is very strange to me but maybe your pulling my trunk, I mean leg.

  5. 5
    GaryGaulin says:

    Well yes Robert there was some humor in my reply. But that’s what happens when making inferences that assume humans were specially created, when all the scientific evidence that exists is against that being true.

  6. 6
    jerry says:

    when making inferences that assume humans were specially created, when all the scientific evidence that exists is against that being true.

    This is certainly not so. There is no science that can explain the quantum leap of mental processing ability over the next species whatever that species is in terms of this characteristic. Certainly not any form of gradualism could explain it which should leave us with hundreds of related species between humans and whatever is currently next. They do not exist nor do we have any evidence they ever existed. And why would such an intelligent species go out of existence?

    So special creation seems to be the best explanation science can provide.

  7. 7
    GaryGaulin says:

    Jerry, demands for minor details that scientists are now working on is not scientific evidence, it’s just being annoying.

    The origin related sciences only have scientific evidence for common ancestry/descent. There is no known scientific evidence against it.

    Intelligent Design is also compatible with common ancestry. See: Is Intelligent Design Theory Incompatible with Evolution? – Casey Luskin
    https://www.youtube.com/watch?v=DayP-KWh44g

    You are in the wrong movement. But Ken Ham will tell you all that you want to hear, regardless of it being scientific nonsense.

  8. 8
    jerry says:

    demands for minor details that scientists are now working on is not scientific evidence, it’s just being annoying.

    I am sorry but it is not just minor details that are missing and while it may be annoying it represents a real show stopper for naturalistic evolution. My guess is that you do not understand the scope of the problem. The human genome is incredibly different from other genomes in the control mechanisms that control the expression of genes. There are several thousand if not more of these control sequences in the human genome not in other genomes that control the expression of proteins uniquely active in developing human neural tissue.

    No other species has close to the amount of these control mechanisms. There is no way such changes in the genome could have happened in any gradualist approach to change over time. Sorry to be annoying but logic and the science get in the way. The science of today has no idea of any mechanism that could explain this difference between humans and any other species.

    Intelligent Design is also compatible with common ancestry.

    Why bring this up. I never mentioned it. The problem with universal common descent is that it reaches a dead end at the Cambrian so in fact UCD is an impossibility. And common descent/ancestry does not point to any mechanism for how it happened since then. I have never seen anyone who could defend a mechanism for common descent since the Cambrian. But this was not mentioned.

    You are in the wrong movement.

    First, I am not sure what is the movement you are talking about. I am a science junkie and my interest is good science and Ken Ham is the last place I would go to for that.

    As I said on another thread, most of what you say is nonsense and definitely not science. But not all.

    I would suggest that you read Denton’s books and participate in the discussion. Your view of the science in evolution will be challenged if you do by a lot of inconvenient facts.

  9. 9
    GaryGaulin says:

    The human genome is incredibly different from other genomes in the control mechanisms that control the expression of genes.

    The problem with universal common descent is that it reaches a dead end at the Cambrian so in fact UCD is an impossibility.

    Adding the “universal” qualifier did not help you make your case against “common descent”. You did not even study the “Theory of Intelligent Design” did you? That is sure insulting! See the chapter on the Cambrian Explosion:

    http://theoryofid.blogspot.com/

    If you have a scientific question pertaining to ID theory then I’ll answer it. Otherwise I will not respond to your misinformation.

  10. 10
    Robert Byers says:

    Gary
    I don’t know of any biological evidence or any evidence we were not created separate. I can’t imagine what it would be!!

  11. 11
  12. 12
    Virgil Cain says:

    All I know that as of today there isn’t any way to (scientifically) test the claim that humans evolved from something other than other humans. We don’t even know of a mechanism that can affect the physical and intellectual transformations required to produce a human from a knuckle-walker or quadruped.

  13. 13
    Robert Byers says:

    On evolution news Ann Gauger had some doctor talk about chins.
    It brouht up a idea.
    Possibly the chin is just a reflection on the big deal about human heads. We have a bigger head relative to the size of our body. in fact its one of the reasons women , uniquely, have pain at childbirth. The head is too big.
    Possibly the chin is tied to helping us keep the head up because its heavy. this men have greater chins because we have bigger heads then women.
    maybe its that simple. maybe not.
    speculation.

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