New research suggests that many of the common orthodontic problems experienced by people in industrialized nations are due to their soft modern diet causing the jaw to grow too short and small relative to the size of their teeth. Dr. Noreen von Cramon-Taubadel, of the University of Kent’s School of Anthropology and Conservation, tested the long-debated theory that the transition from a largely hunter-gatherer to an agricultural subsistence strategy across many parts of the world has had an effect on the growth and development of the human skull and lower jaw. The shapes of the cranium and mandible of 11 globally distributed populations were compaired against models of genetic, geographic, climatic, and dietary differences. She found that lower jaw shape, and to some extent the shape of the upper palate, was related to the diet of populations, while the cranium was strongly related to the genetic relationships of the populations. The lower jaw reflects whether populations are primarily hunter-gatherer or agriculturalist in nature, irrespective of what part of the world they come from. This suggests that chewing behavior causes the lower jaw to grow and develop differently in different subsistence groups, while the skull is not affected in the same way. Overall, the hunter-gather groups had longer and narrower mandibles, indicating more room for the teeth to erupt correctly, while the agriculturalists had generally shorter and broader mandibles, increasing the likelihood of dental crowding. Dr. von Cramon-Taubadel says, “Chewing behavior appears to cause the lower jaw to develop differently in hunter-gatherer versus farming populations, and this holds true at a global level. What is interesting is that the rest of the skull is not affected in the same way and seems to more closely match our genetic history.”
(Source: ScienceDaily, November 22, 2011)
