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Comment by will_brown | Hacker News Reader

Aside from the chin...look at the picture of the modern human skull compared to the Neandethal-era skull. Notice Neandethal-era skull has a perfect bite and the modern human skull has an overbite. The overbite is the direct result of humans developing/using eating utensils (this fact may have actually been from a recent HN front page post).

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The overbite-utensil hypothesis is interesting. But why do overbites exist in modern human societies that eat almost entirely with their hands?

In hindsight, I really didn't mean to emphatically state:

"The overbite is the direct result of humans developing/using eating utensils"

I just meant to mention the theory and that I thought I first learned about the theory on the HN front page, but perhaps I read about it elsewhere anyway.

Looking just quickly at Google I believe the theory originates with Anthropologist, C. Loring Brace [1] a specialist in the evolution of hominid teeth[2].

[1]http://en.wikipedia.org/wiki/C._Loring_Brace [2]http://benedante.blogspot.com/2013/03/overbites-and-history-...

Can't get over how Lamarckian this sounds. How long have we been eating with utensils? Long enough for such a radical change? And is an overbite really such a disadvantage that it would select you right out of the gene pool?

Human physical genetic changes have accelerated in the last 50,000 years. Probably accompanying new pressures brought by living in social groups. But since the fork was only invented 400 years ago, maybe utensils is a reach.

Surely "utensils" includes more than just modern style metal forks? I don't think it's a stretch to say that the use of tools of any kind in the eating process could remove specific evolutionary pressures that would otherwise inhibit some individuals from reproducing.

I think it is a developmental rather than an evolutional effect.

Here's the presumable popularization of the idea:

https://books.google.com/books?id=5_EyCAAAQBAJ&lpg=PT76&ots=...

Which was then mentioned in the Atlantic:

http://www.theatlantic.com/health/archive/2013/01/how-forks-...

I don't get this statement, and it goes against my understanding of evolutionary forces.

Of the 5 evolutionary forces that I am aware of, founder effects, genetic drift, mutation, migration and selection, only one "responds" to the environment (selection). To respond to an event such as the invention of eating utensils, selection would dictate that a particular trait would have to give a survival/mating advantage over not having it.

It is suggested that those with an overbite we able to survive/mate better in the presence utensils than those without an overbite?

I know nothing about biology, but how about this:

The evolutionary path was influenced via selection. Those who made and used tools were more likely to survive/mate successfully, and those who made and used tools also tended to use them as eating utensils, which mechanically leads to an overbite. So eating with a fork doesn't directly lead to being selected for survival, but it's likely if you eat with utensils you also use other tools for things like hunting, defence, etc. and that does lead to increased survival.

It doesn't work like that.

That type of association is called "Lamarckian" after Jean-Baptiste Lamarck who posited that animals can "pass on characteristics that it acquired during its lifetime to its offspring"[1]. But animals do not pass on traits they acquired during their lifetime via genetics.

So even if utensils over one's life caused a overbite, it would not be transmitted via genetics to one's offspring. In order for evolution and utensils to interact via selection, it would have to be the case in which there was a genetic trait associated with an overbite that made you more fit when using utensils than those without it, thus out-mating the competition.

[1]http://en.wikipedia.org/wiki/Lamarckism

Why can't the opposite be true; those without an overbite are able to survive/mate better in the absence of utensils? Then the modern presence of overbite is easily explained as genetic drift.

I would guess that many modern mutations could be explained this way -- human invention alleviates evolutionary pressure keeping historically negative traits from flourishing.

It's surprising just how recent it was, too -- Richard III's skull, for example, clearly demonstrates the "perfect bite", and he lived just a bit more than 500 years ago.

https://www.google.com/search?q=king+richard+iii+skull&tbm=i...

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