Researchers at the School of Anthropology and Conservation at the University of Kent studying 11 globally distributed populations have found that as humans shifted from a hunter-gatherer to an agricultural lifestyle, their jawbones became shorter and broader. This could explain the relatively high incidence of dental crowding and dental misalignment in modern populations.

The relationship between global mandibular shape variation and subsistence economy was tested, while controlling for the potentially confounding effects of shared population history, geography and climate. The results of the study1 support notions that a decrease in masticatory stress among agriculturalists caused the mandible to grow and develop differently. This also explains why there is often a mismatch between the size of the lower face and the dentition.