Here is some recent research on the impact of changing diet on human jaw structure. The main thrust is that the switch to sedentary agricultural communities with predominantly plant-based diets resulted in the smaller jaws and therefore crooked teeth, compared to the longer jaws of hunter-gatherers. It is not known whether this is an evolutionary change or a developmental change, but it does indicate that the human jaw structure reflects a diet including meat.
“Thus hunter-gatherers tended to have longer (more jutting) and narrower lower jaws, whereas those of farmers were relatively shorter and wider. But the form of the crania did not show this correlation, with one exception: The shape of the palate of the upper jaw, which is closely associated with the lower jaw and involved in chewing, also varied to some degree between farmers and hunter-gatherers.”
[Author Noreen von Cramon-Taubadel] concludes that the transition to farming—which involved the domestication of plants and animals, a major increase in food processing, and thus consumption of easier to chew food altered the shape of the human jaw, making it shorter and less robust. And this shortening of the jaw, she suggests, led to greater crowding of the teeth and the orthodontist bills that plague many modern families.
From news article:
http://news.sciencemag.org/sciencenow/2011/11/crooked-teeth-blame-early-farmer.html
Source:
http://www.pnas.org/content/108/49/19546
Global human mandibular variation reflects differences in agricultural and hunter-gatherer subsistence strategies
Noreen von Cramon-Taubadel, Department of Anthropology, School of Anthropology and Conservation, University of Kent, Canterbury CT2 7NR, United Kingdom
Abstract
Variation in the masticatory behavior of hunter-gatherer and agricultural populations is hypothesized to be one of the major forces affecting the form of the human mandible. However, this has yet to be analyzed at a global level. Here, the relationship between global mandibular shape variation and subsistence economy is tested, while controlling for the potentially confounding effects of shared population history, geography, and climate. The results demonstrate that the mandible, in contrast to the cranium, significantly reflects subsistence strategy rather than neutral genetic patterns, with hunter-gatherers having consistently longer and narrower mandibles than agriculturalists. These results support notions that a decrease in masticatory stress among agriculturalists causes the mandible to grow and develop differently. This developmental argument also explains why there is often a mismatch between the size of the lower face and the dentition, which, in turn, leads to increased prevalence of dental crowding and malocclusions in modern postindustrial populations. Therefore, these results have important implications for our understanding of human masticatory adaptation.
On the “other primates eat meat” issue, video evidence has shown that chimpanzees groups will deliberately track and attack other chimpanzee groups for territory- and will eat those that they kill.
