Many people in the post-industrialized era have problems with crowded teeth because there’s not enough room in their lower jaws. The teeth sometime erupt crookedly and cause malocclusions, or misalignments of the teeth between the upper and lower jaws, which can cause chewing problems.

Some scientists believe that jaw size is inherited, and many have factored this presumption into their speculations about human evolution. But a new study has confirmed that human jaw sizes and shapes vary according to diet, not just ancestry.

Anthropologist Noreen von Cramon-Taubadel published the study in the Proceedings of the National Academy of Sciences. In it, she compared the jaw robustness of five hunter-gatherer populations to that of six agriculturalist populations.

Though there was much overlap, the data clearly showed that the hunter-gatherer groups—including populations of the Alaskan Inuit, Australians, and Central Africans—tended to have more room in their mandibles (lower jaws). The diets of these populations consist primarily of unprocessed foods that require more chewing. Agriculturalist groups, including Italians and Japanese, had “relatively short and broad mandibles.”1

Many of those who had to chew their food more vigorously developed larger mandibles and thus had enough tooth space. And that clearly implies that all human populations can grow different-size mandibles in response to chewing needs. Dr. von Cramon-Taubadel checked her results against other possible causes of the jaw differences and ruled out genetic ancestry. If changing jaw sizes is not directly inherited, then it cannot be ascribed to evolution, because evolution requires new traits to be heritable….

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