Human jawbone structure influenced by diet and genetics

According to scientists at Johns Hopkins, human jawbone structures are determined not only by diet but also by genetics; despite minimal existing evidence from fossil records, these findings may help envisage the food habits of an ancient population. They are also expected to help scientists determine the genetic relationship between fossils.

Graduate student at the Johns Hopkins Center for Functional Anatomy and Evolution, and study lead author, Megan Holmes, stated: “Our research aimed to see how much of the mandible’s-or jaw bone’s-shape is plastic, a response to environmental influences, such as diet, and how much is genetic. The idea that function influences the shape of jaw bones is great for the archeological record in terms of discovering the diet of a population, and it’s also really useful for reconstructing the fossil record-finding which fossils are related to which, and how.”

The Arikara and Point Hope American Indians populations were chosen by the group for their study since they were genetically inaccessible from other groups and had varied food habits.

Holmes stated: “The jaw bones were similar in children before they were old enough to start chewing, but different in adulthood, which implies that this divergence is likely a functional result of their diet and the use of their jaw, rather than genetics.”

Very specific parts of the jaw bones were examined by the team to establish an association with specific dietary habits. For instance, round, wide jaw bones were observed in the Point Hope population as a consequence of having to exert more effort to chomp a tougher diet. On the contrary, the Arikara did not have this expansion which clearly pointed towards a subtle chewing need of a softer diet.

The June 23 online issue of the American Journal of Physical Anthropology (ANI) published the findings of the study.