Study finds even earliest farmers had malocclusion

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Study finds even earliest farmers had malocclusion

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Healthy lower jaw of an mesolithic hunter-gatherer (left) compared to one of an early neolithic farmer with malocclusion. (Photograph: Olivia Cheronet)
Dental Tribune International

By Dental Tribune International

Thu. 12 February 2015

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DUBLIN, Ireland: Malocclusion and dental crowding appear to have spread concomitant with the prehistoric transition from hunting and gathering to agriculture. A new international study has found that both conditions first became common among the world’s earliest farmers 12,000 years ago in South-West Asia.

In the study, a team of international researchers analysed the mandibular and crown dimensions of 292 archaeological skeletons from the Levant, Anatolia and Europe from between 28,000 and 6,000 years ago. The results show a clear separation between European hunter-gatherers, Near Eastern/Anatolian semi-sedentary hunter-gatherers, and European farmers based on the form and structure of their jawbones.

“Our analysis shows that the lower jaws of the world’s earliest farmers in the Levant are not simply smaller versions of those of the predecessor hunter-gatherers, but that the lower jaw underwent a complex series of shape changes commensurate with the transition to agriculture,” said Prof. Ron Pinhasi from the School of Archaeology at University College Dublin and lead author.

With the shift to agriculture, solid foods like wild uncooked vegetables and meat were replaced with mainly soft cooked or processed foods like cereals and legumes. Soft cooked foods require less chewing, which in turn lessens the size of the jaws. Without a corresponding reduction in the dimensions of the teeth, this often results in malocclusion and dental crowding, since there is inadequate space in the jaw. The link between chewing, diet, and related dental wear patterns is well known in the scientific literature, and it has been suggested that malocclusion is associated with urbanisation. Previously, however, it was unclear as to whether its high prevalence began 8,000 years before with the beginning of sedentism and a change in nutrition.

While the hunter-gatherer populations show an almost perfect harmony between the lower jaw and teeth, this harmony is not an attribute of the earliest farmers. The correlation of inter-individual mandibular and dental distances found in the case of the hunter-gatherers was not evident in the semi-sedentary hunter-gatherers and farming groups. This suggests that the harmony between teeth and jawbone was disrupted with the shift towards agricultural practices and the resulting dietary changes among the different populations.

Today, malocclusion and dental crowding affect around one in five people in modern-world populations.

The study, titled “Incongruity between affinity patterns based on mandibular and lower dental dimensions following the transition to agriculture in the Near East, Anatolia and Europe”, was published online on 4 February in the PLOS ONE journal.

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