Doctoral Dissertation Research: Morphological Integration in the Hominid Cranial Base

本研究将评估古人类颅底的功能形态学，及其在重建早期人类进化模式（即古人类系统发育模式）中的作用。这项研究意义重大，因为它将批判性地研究一个解剖区域的功能和系统发育关系，这个解剖区域在本世纪大部分时间里一直是争论的主题。在这个过程中，它将收集定量的姿势数据，这将极大地提高我们将灵长类动物的位置行为和形态联系起来的能力。最后，它将提出一种方法，据此功能和结构推断可用于系统发育分析。也就是说，在功能或结构上彼此相关的解剖特征将被分组成复合体，然后在分支分析（一种系统发育重建方法）中被视为一个单位（即加权为单个特征）。这种方法适用于生物学所有领域的分支分析，无论所研究的是何种生物体或解剖区域。颅底是功能和系统发育研究的合适解剖焦点。从功能形态学的角度来看，多种因素可能影响颅底形态。这些因素包括大脑大小、姿势、发声、咀嚼和面部结构。因此，有许多功能假设可供测试。从系统发育的角度来看，颅基本特征在围绕早期人类进化模式的争论中起着至关重要的作用。我们自己属的早期成员（例如，能人，直立人）与一些澳大利亚阿片类物种共享许多先进的基本颅特征。这些特征要么表明这些物种和我们属的祖先之间有密切的进化关系，要么表明先进的颅底特征是在两个或多个早期人类谱系中独立进化的。最后，从历史的角度来看，颅底很重要。人们早就认识到，人类的颅底不同于其他灵长类动物。结果，一个基本的颅内特征被用来确定第一个被发现的南方古猿头骨是人类的祖先。

The research proposed here will evaluate the functional morphology of the hominid cranial base, and its role in reconstructing patterns of early human evolution (i.e., patterns of hominid phylogeny). This research is significant because it will critically examine the functional and phylogenetic relationships of an anatomical region that has been the subject of debate for most of this century. In the process of doing so, it will collect quantitative postural data that will vastly improve our ability to relate primate positional behavior and morphology. Finally, it will propose an approach whereby functional and structural inferences may be used in phylogenetic analysis. Namely, anatomical features that are functionally or stucturally related to each other will be grouped into complexes, and will then be treated as a unit (i.e., weighted as a single feature) in a cladistic analysis (a method of phylogeny reconstruction). This approach is relevant to cladistic analyses in all fields of biology, regardless of the organism or anatomical region that is under investigation. The cranial base is an appropriate anatomical focus for functional and phylogenetic research. From the standpoint of functional morphology, a wide range of factors may influence basicranial form. Such factors include brain size, posture, vocalization, mastication, and facial architecture. Consequently, there are many functional hypotheses available for testing. From a phylogenetic standpoint, basicranial traits play a vital role in the controversey surrounding patterns of early human evolution. Early members of our own genus (e.g., Homo habilis, Homo erectus) share a number of advanced basicranial features with some australopiothecine species. These features either indicate a close evolutionary relationship between these species and the ancestral members of our genus, or that advanced basicranial characters evolved independently in two or more lineages of early humans. Finally, the cranial base is important from an historical perspective. It has long been recognized that the cranial base of humans is distinct from that of other primates. As a result, a basicranial feature was among those used to identify the first recovered australopithecine skull as being a human ancestor.