Jaws and creationism

Jaws and creationism. Unfortunately I’m not talking about the shark (although a creationist horror film would be awesome), but the human jaw. You see, each of our faces is different and for the most part this seems to be because neutral mutations accrue, changing our


Jaws and creationism. Unfortunately I’m not talking about the shark (although a creationist horror film would be awesome), but the human jaw.

You see, each of our faces is different and for the most part this seems to be because neutral mutations accrue, changing our skull but not doing so enough to be good or bad for us so no one variant gets spread throughout the population. Instead, we just gradually diversify.

Creationists, both professional and not, have leapt upon a recent paper on jaw variation. It had discovered some parts of our jaw vary because of diet, not these neutral genetic changes genetics.

It noted that  jaw variation is correlated with diet, with a hunter-gatherer diet being associated with larger jaws, which is not what one would expect if it were the product of neutral mutations. If that were the case, one would predict the variation be random, like the mutations themselves.

There’s not many funny comments that can be made about a jaw chart. This isn’t one of them.

These variants aren’t correlated with genetics either, suggesting that something else is causing them to vary and since it is correlated with diet, perhaps it is that.

It is not unknown for behaviour to alter one’s body, with larger muscles prompting bone to thicken. A similar mechanism might be at play here, with a hunter-gatherer diet exerting more pressure on the jaw causing it to grow differently.

The other thing the research found was that parts of the jaw didn’t change together. For example, a variant of the upper jaw might not always be found with the same variant of the lower jaw. This suggests that, whilst non-genetic changes mask recent evolution, different parts of the jaw can evolve independently.

All in all it’s your typical study. Interesting but not overwhelmingly so, certainly not blog worthy (I only bring you the very best, ladies and gentlemen). So what is it the creationists have latched onto?

The ICR article focuses on the fact that evolution isn’t responsible for the variation.

“If changing jaw sizes is not directly inherited, then it cannot be ascribed to evolution, because evolution requires new traits to be heritable.”

Quite what they’re implying here I don’t know. That evolution wasn’t responsible for this trait, therefore it wasn’t involved in the generation of any trait? Obviously that argument doesn’t work, which is probably why they merely implied it.

Indeed, they offer no actual argument which concludes with creationism, making their leap to it all the more jarring. It’s literally

  1. Jaw variation isn’t evolved
  2. ???
  3. Creationism

No joke, that internet meme is genuinly the argument they offer.

credit for variable-response bone growth should go to the bone-building cells and their interrelated sensory mechanisms that actively adapt according to the needs of processing food. Of course, the credit for such bone growth capability actually belongs to the Creator

Creation is something that’s throw in at the end and does not follow from their argument.

The only other point of interest in the article is their claim that the scientist responsible for the study “asserted that natural selection “acted” without proof or evidence” quoting.

“Masticatory [chewing] pressure acts preferentially on the mandible rather than the maxillary [upper jaw] region, [and] the results presented here suggest that the mandible can evolve independently.”

However, as any who reads the quote (and the paper) fully can appreciate, the researcher is just noting that since the upper and lower jaw aren’t completely interlinked they can evolve independently, making no assertions about natural selection.

The only other context in which she talks about selection is to note that her study hasn’t ruled it out. Indeed, since she found that some genes were correlated with certain aspects of the jaw then there is some selection occurring. To suggest that it is a mere “assertion” is borderline dishonest.

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4 thoughts on “Jaws and creationism”

  1. eyeonicr says:

    That’s a much better explanation of the paper. Thank you!

  2. ScienceDefined says:

    Great post! Although my understanding was also that a trait has to be heritable to contribute to evolution.

    1. Adam Benton says:

      Indeed it does and this article was thus noting there are some jaw variants that weren’t produced by evolution. That doesn’t mean the jaw is completely independent of evolution or that evolution doesn’t happen, or whatever it was the creationists were trying to imply.

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