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Edited by Timothy D. Weaver, University of California, Davis, CA, and accepted by the Editorial Board October 19, 2011 (received for review August 12, 2011)
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.
Footnotes
- ↵1E-mail: n.von-cramon{at}kent.ac.uk.
Author contributions: N.v.C.-T. designed research, performed research, collected data, analyzed data, and wrote the paper.
The author declares no conflict of interest.
This article is a PNAS Direct Submission. T.D.W. is a guest editor invited by the Editorial Board.
This article contains supporting information online at www.pnas.org/lookup/suppl/doi:10.1073/pnas.1113050108/-/DCSupplemental.
Global human mandibular variation reflects differences in agricultural and hunter-gatherer subsistence strategies
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