Centre for Human Evolution Research, Natural History Museum, London, United Kingdom; Department of Anthropology, University College London, London, United Kingdom.
Centre for Human Evolution Research, Natural History Museum, London, United Kingdom; Department of Human Evolution, Max Planck Institute for Evolutionary Anthropology, Leipzig, Germany.
J Hum Evol. 2022 Jul;168:103210. doi: 10.1016/j.jhevol.2022.103210. Epub 2022 May 24.
Differences in morphology among modern humans and African apes are frequently used when assessing whether hominin fossils should be attributed to a single species or represent evidence for taxic diversity. A good understanding of the degree and structure of the intergeneric, interspecific, and intraspecific variation, including aspects such as sexual dimorphism and age, are key in this context. Here we explore the variation and differences shown by the maxilla of extant hominines, as maxillary morphology is central in the diagnosis of several hominin taxa. Our sample includes adults of all currently recognized hominine species and subspecies, with a balanced species sex ratio. In addition, we compared the adults with a small sample of late juveniles. The morphology of the maxillae was captured using three-dimensional landmarks, and the size and shape were analyzed using geometric morphometric methods. Key observations are that 1) the maxillae of all extant hominine species and subspecies show statistically significant differences, but complete separation in shape is only seen at the genus level; 2) the degree of variation is not consistent between genera, with subspecies of Gorilla being more different from each other than are species of Pan; 3) the pattern of sexual shape dimorphism is different in Pan, Gorilla, and Homo, often showing opposite trends; and 4) differentiation between maxillary shapes is increased after adjustment for static intraspecific allometry. These results provide a taxonomically up-to-date comparative morphological framework to help interpret the hominin fossil record, and we discuss the practical implications in that context.
现代人种和非洲猿类之间的形态差异在评估人属化石是否应归为一个物种或代表分类多样性的证据时经常被使用。在这种情况下，充分了解属间、种间和种内变异的程度和结构，包括性二态性和年龄等方面，是至关重要的。在这里，我们探讨了现生人属的上颌骨所表现出的变异和差异，因为上颌骨形态是几种人属分类群诊断的核心。我们的样本包括所有目前公认的人属物种和亚种的成年人，具有平衡的物种性别比例。此外，我们还将成年人与一小部分晚期青少年进行了比较。上颌骨的形态使用三维地标进行捕捉，并使用几何形态测量方法分析大小和形状。主要观察结果是：1）所有现生人属物种和亚种的上颌骨都表现出统计学上显著的差异，但仅在属级水平上才能看到完全分离的形状；2）变异程度在属之间并不一致，大猩猩亚种之间的差异比黑猩猩物种之间的差异更大；3）性形态二态性的模式在黑猩猩、大猩猩和人类中不同，通常表现出相反的趋势；4）在调整静态种内异速生长后，上颌骨形状的分化增加。这些结果提供了一个最新的分类比较形态学框架，有助于解释人属化石记录，我们还在该背景下讨论了其实践意义。
