Department of Anthropology, University of Kent
Saturday All day, Plaza Level
Variation in the masticatory behavior of hunter-gatherer and agricultural populations is hypothesized to be one of the major forces affecting human mandibular form. 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. Materials comprised matched genetic, morphometric, geographic, climatic, and subsistence data collated for eleven globally distributed human populations. Morphometric data included configurations of landmarks for the mandible, and for three regions of the cranium involved in mastication (insertions of the temporalis muscles, the zygomatic-temporal region and the palate-maxillary region) as well as two non-masticatory regions (the vault and basicranium). Data were analyzed using full and partial Mantel tests.
The results demonstrate that the mandible, in contrast with cranial regions, 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 post-industrial populations. Therefore, these results have important implications for our understanding of human masticatory adaptation.
Funding to undertake this research was received from the EU SYNTHESYS initiative (FR-TAF 1989, AT-TAF 2189).