School of Natural Sciences and Psychology, Liverpool John Moores University, Liverpool, UK.
Evolutionary Studies Institute and Centre for Excellence in PaleoSciences, University of the Witwatersrand, Private Bag 3, WITS 2050, Johannesburg, South Africa.
Am J Primatol. 2019 Mar;81(3):e22953. doi: 10.1002/ajp.22953. Epub 2019 Jan 21.
The reduction in dental size and mandibular robusticity is regarded as a major trend in human evolution, traditionally considered the result of the peculiar extra-oral food processing skills of Homo. The use of stone tools and fire would have allowed our ancestors to chew softer food in smaller bite size, thus relaxing the selective pressures to keep a large dentition and a robust lower jaw. This perspective assumes that differences in dental size and mandibular robusticity in hominins represent functional dissimilarities. This study uses a catarrhine comparative approach to test this fundamental assumption of the hypotheses on dental and mandibular reduction in Homo. A sample of extant catarrhines and fossil hominins was used to test for correlations between dental size, mandibular robusticity, and dietary proxies, the latter include diet quality, diet heterogeneity, feeding time, and microwear variables. The effects of phylogeny and body size were considered. Findings support the association between technological developments in Homo and reduction in incisor size and mandibular corpus robusticity, though not for premolar, molar size, and symphyseal robusticity. These results challenge the functional interpretation of postcanine reduction and symphyseal changes in the genus Homo.
牙齿尺寸减小和下颌骨粗壮度降低被认为是人类进化的主要趋势，传统上被认为是人类特有的口腔外食物加工技能的结果。石器和火的使用使我们的祖先能够咀嚼更小、更软的食物，从而减轻了保持大牙齿和强壮下颌骨的选择压力。这种观点假设在人属中，牙齿尺寸和下颌骨粗壮度的差异代表了功能上的差异。本研究使用类人猿的比较方法来检验关于人类牙齿和下颌骨减小的假设的这一基本假设。利用现生类人猿和化石人属的样本，检验了牙齿尺寸、下颌骨粗壮度与饮食指标（包括饮食质量、饮食多样性、进食时间和微观磨损变量）之间的相关性。还考虑了系统发育和体型的影响。研究结果支持了在人类中技术发展与门齿尺寸减小和下颌体粗壮度降低之间的关联，但不支持前臼齿、臼齿尺寸和联合部粗壮度的关联。这些结果对人属中后齿减小和联合部变化的功能解释提出了挑战。
