Doctoral Dissertation Improvement: The Influences of Brain Anatomy on Facial Positioning in Anthropoid Primates: Implications for Modern Human Origins

本论文将研究类人型灵长类动物面部骨骼和脑壳的解剖关系的变异。特别是，这项研究将检验三个假说，它们代表了面部骨骼相对于头骨其他部分的位置的非互斥解释。前两个假设假设类人灵长类动物面部骨骼的位置是由大脑的解剖结构决定的--分别由大脑的整体大小和颞叶的大小决定。第三种假说代表了另一种观点，即面部在类人猿中的位置是由大脑的解剖结构决定的，而是认为面部骨骼本身的大小决定了它相对于脑壳的位置。这些假说将使用从类人头骨的数字射线照片和类人脑的核磁共振扫描收集的数据进行验证。假说的预测将使用度量学和几何形态计量学方法进行评估，并将使用系统发育比较方法对样本中分类群之间的进化关系进行统计调整。这项研究的结果将对理解类人灵长类动物的头面部结构具有重要的意义，并将对理解智人的衍生颅形具有特殊的意义。在这篇论文的过程中收集的射线照片将发布在一个免费的在线数据库上，这将对身体人类学家和其他科学家以及教育工作者有用。该项目还将支持对一位有前途的科学家进行研究生培训。

This dissertation research will investigate variation in the anatomical relationship of the facial skeleton and the braincase in anthropoid primates. Particularly, this study will test three hypotheses that represent non-mutually exclusive explanations for the position of the facial skeleton relative to the rest of the skull. The first two hypotheses posit that the position of the facial skeleton in anthropoid primates is determined by the anatomy of the brain -- by the overall size of the brain and the size of the temporal lobe, respectively. The third hypothesis represents an alternative to the notion that facial positioning in anthropoids is determined by the anatomy of the brain, and suggests instead that the size of the facial skeleton itself determines its position relative to the braincase. The hypotheses will be tested using data collected from digital radiographs of anthropoid skulls and MRI scans of anthropoid brains. The predictions of the hypotheses will be evaluated using metric and geometric morphometric methods, and phylogenetic comparative methods will be employed to adjust statistically for the evolutionary relationships among the taxa in the sample. The results of this research will have important implications for understanding craniofacial architecture in anthropoid primates and will specific relevance for understanding the derived cranial form of Homo sapiens. The radiographs collected in the course of this dissertation will be published on a free online database that will be useful for physical anthropologists and other scientists and for educators. This project will also support the graduate training of a promising scientist.