March 8, 2012

Lower jaw shaped by diet

That is what anthropometrist Noreen von Cramon-Taubadel thinks, based on the differences between hunter-gatherers (who have broader jaws) and farmers/herders (who have narrower ones).

... the lower jaw reflects whether populations are primarily hunter-gatherer or agriculturalist in nature, irrespective of what part of the world they come from. This therefore suggests that chewing behaviour causes the lower jaw to grow and develop differently in different subsistence groups, while the skull is not affected in the same way. 

Overall, the hunter-gather groups had longer and narrower mandible, indicating more room for the to erupt correctly, while the agriculturalists had generally shorter and broader mandibles, increasing the likelihood of dental crowding.

However it must be noted that the first known case of impacted wisdom tooth happened in a Magdalenian forager. Magdalenian people in general had quite narrow, modern, jaws, like Chancelade Man (right), so it may be a more complex matter, specially as meat, cereals and other foods can be cooked in many different ways, regardless of economical paradigm.

Source: PhysOrg (found via Pileta).

5 comments:

  1. Yeah, there have been several studies recently arguing for a significant role of diet on not just jaw, but also skull shape. Of course this is a difficult topic, because clearly there are genetic predispositions, as well.

    The tooth-crowding as caused by more modern diets is believable, since selection should have ensured functional and pretty teeth, but probably does not work on a few 1,000 years time scale on something rather weak. Of course, our jaws have become less robust over the past 200,000 years or so anyway, so there is another contributing factor.

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  2. What about populations showing rather common traits such as a broad jaw despite having switched to a herder diet for millenia ?

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  3. I can't say because I could not find the paper. It'd be interesting to see case by case. Still I strongly suspect that it has more to do with cooking traditions than economical model.

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  4. In Britain 35% of people today do not develop wisdom teeth - although sharing 'similar' diets.

    I would imagine that this therefore genetic rather than environmental. As she is cro-magnon and about the same percentage with wisdom teeth have that haplogroup, is there a correlation?

    RJL

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  5. "... is there a correlation?"

    I do not know. You may be onto something but a wider analysis (i.e. beyond Europe, clear data) is probably needed to get an idea. I know that my mother, who is half-Italian and hence more likely to have more "Neolithic" ancestry did not develop wisdom teeth, while I had all four instead (one of them impacted, the other three not because I had already lost molars by then - sweet tooth that I am) and so do most of my direct relatives (which are only 1/4 or nothing North Italian).

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