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

本论文主要研究类人猿面部骨骼与脑壳解剖关系的变异。特别地，这项研究将测试三个假设，这些假设代表了面部骨骼相对于头骨其余部分的位置的非互斥解释。前两种假设认为，类人猿灵长类动物面部骨骼的位置是由大脑的解剖结构决定的——分别由大脑的总体大小和颞叶的大小决定。第三种假说代表了另一种观点，即类人猿的面部定位是由大脑的解剖结构决定的，相反，它表明面部骨骼本身的大小决定了它相对于脑壳的位置。这些假设将使用从类人猿头骨的数字x光片和类人猿大脑的核磁共振扫描中收集的数据进行测试。这些假设的预测将使用度量和几何形态计量方法进行评估，并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猿灵长类动物的颅面结构具有重要意义，并将对理解智人的衍生颅形态具有特定的相关性。在这篇论文的过程中收集的x光片将会发布在一个免费的在线数据库中，这将对体质人类学家和其他科学家以及教育工作者很有用。这个项目还将支持培养一名有前途的科学家。

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.