Research Centre in Evolutionary Anthropology and Palaeoecology, School of Natural Sciences and Psychology, Faculty of Science, Liverpool John Moores University, Liverpool, L3 3AF, United Kingdom.
Centre for Anatomical and Human Sciences, Hull York Medical School, University of York, York, YO10 5DD, United Kingdom.
Am J Phys Anthropol. 2018 Sep;167(1):84-96. doi: 10.1002/ajpa.23606. Epub 2018 May 8.
Although the evolution of the hominin masticatory apparatus has been linked to diet and food processing, the physical connection between neurocranium and lower jaw suggests a role of encephalization in the trend of dental and mandibular reduction. Here, the hypothesis that tooth size and mandibular robusticity are influenced by morphological changes in the neurocranium was tested.
Three-dimensional landmarks, alveolar lengths, and mandibular robusticity data were recorded on a sample of chimpanzee and human skulls. The morphological integration between the neurocranium and the lower jaw was analyzed by means of Singular Warps Analysis. Redundancy Analysis was performed to understand if the pattern of neuromandibular integration affects tooth size and mandibular robusticity.
There is significant morphological covariation between neurocranium and lower jaw in both chimpanzees and humans. In humans, changes in the temporal fossa seem to produce alterations of the relative orientation of jaw parts, while the influence of similar neurocranial changes in chimpanzees are more localized. In both species, postcanine alveolar lengths and mandibular robusticity are associated with shape changes of the temporal fossa.
The results of this study support the hypothesis that the neurocranium is able to affect the evolution and development of the lower jaw, although most likely through functional integration of mandible, teeth, and muscles within the masticatory apparatus. This study highlights the relative influence of structural constraints and adaptive factors in the evolution of the human skull.
尽管人属咀嚼器官的进化与饮食和食物加工有关，但颅腔与下颌骨之间的物理联系表明，脑化在牙齿和下颌骨缩小的趋势中起着一定的作用。本研究检验了颅腔形态变化是否会影响牙齿大小和下颌骨粗壮度这一假说。
本研究记录了一组黑猩猩和人类颅骨的三维标志、牙槽长度和下颌骨粗壮度数据。采用奇异翘曲分析方法分析颅腔与下颌骨之间的形态整合。冗余分析用于了解神经-下颌整合模式是否会影响牙齿大小和下颌骨粗壮度。
在黑猩猩和人类中，颅腔与下颌骨之间存在显著的形态协同变化。在人类中，颞窝的变化似乎会改变颌骨各部分的相对方位，而在黑猩猩中，类似的颅腔变化的影响则更加局限。在这两个物种中，后齿槽牙槽长度和下颌骨粗壮度与颞窝形状变化有关。
本研究结果支持了这样一种假说，即颅腔能够影响下颌骨的进化和发育，尽管这种影响很可能是通过咀嚼器官中下颌骨、牙齿和肌肉的功能整合来实现的。本研究强调了结构约束和适应因素在人类颅骨进化中的相对影响。
