http://wholehealthsource.blogspot.com/2009/11/malocclusion-disease-of-civilization_24.html

The main different idea is that the use of utensils is irrelevant. The strongest predictor of occlusion is the toughness of the food being eaten.

There’s a distinct difference between a real overbite, where the molars and premolars don’t mate properly and chewing is impacted, and this fantasy overbite, where somehow everything magically lines up anyways.

Then, there’s the thing where the two central front incisors tend to be longer than the flanking pair (which prevents the jaw from closing properly at all).

Our canines are also not placed to interlock properly with the incisors surface-to-surface, and frankly our dentition is different from the other great apes in so many more dramatic ways that picking on the way our incisors line up seems to be missing the forest from the trees.

Unlike the other great apes, our teeth are strongly adapted to omnivory – our molars and premolars are often cited for their superior efficacy in chewing meat. The fact that our front teeth are different as well should surprise no-one.

This sort of thing is just about a perfect example of taking the correlation and running. 

Without any strong evidence they both seem ‘just so’ stories.

This is the thing. We have to be careful of stories that sound good. This is a good theory, and perhaps the best one, but we will never really be able to prove this.

Here’s a study showing the same sort of change over an even shorter, more recent period, from 1870-1970. http://link.springer.com/article/10.1007%2Fs12548-010-0038-4?LI=true
 It could be due to the development of the hyperspoon or the superfork. Or aliens dicking around with us, or petunias. Anything’s possible, especially when you don’t have to put forward any evidence.

edit: not actually sure it’s applicable, since the author mentions changing from an “even” bite to an overbite, but it’s still interesting to think about.

There are cultures that mainly eat with their hands. Are there big morphological differences in their bite? From this hypothesis, the answer should be, of course.

It’s suggested that how we eat affects how our facial muscles develop, which affects the position our jaws return to comfortably when we relax those muscles.

Chairs don’t cause our children to be born with poor posture by Lamarckian mechanisms either – but we still send them off to school, where they’re made to sit in chairs, which affects their posture as they grow up.  Same deal.

This change is far too recent for any evolutionary explanation. Rather, it seems to be a question of usage. An American anthropologist, C. Loring Brace, put forward the thesis that the overbite results from the way we use cutlery, from childhood onwards.

The idea is that we are born without an overbite, and our facial muscles adapt in each new generation to the use of utensils (if we are raised to use them) by holding our jaws in an overbite position, or to eating without utensils (if we are raised not to) by holding the jaw without an overbite.

You can probably position your jaw in a non-overbite position just fine now, but you’ll feel a stretch in your jaw muscles. I guess the idea is that if you had eaten since childhood without utensils, your facial muscles would have developed differently, so the relaxed position would be straight-on, and you’d feel a stretch if you held your jaw in an overbite.

By the same token, chairs didn’t cause us to evolve heritable poor posture, but our cultural habit of spending all day sitting in them is giving each new generation poor posture starting at school age.

if, for example, utensil-users exterminated all children with an underbite

Then the “no underbite people” would be currently occupying a small country somewhere like the middle east and fighting anybody who looks at them the wrong way.

We are not simple.

“Us all”?