Doctoral Dissertation Improvement: Quantitative Analysis of Temporal Bone Pneumatization in Homininae

该项目将研究颞骨气化的进化和生长相关变化，这是导致成人颞骨充满空气的空洞的广泛过程。关于古人类系统发育和颅面进化的重要结论包括颞骨气化作为系统发育或物种特异性的标记。尽管其先前已被纳入进化分析，但关于古人类颞骨充气的进化和发育变化，以及观察到的充气变化的发育和功能基础，仍存在许多问题。要在人类进化研究中正确地纳入这一特征，需要对颞骨充气的发展和原因有透彻的了解，特别是与其他显示进化变化的重要特征的关系。拟议的研究将完成三个目标，以确定颞骨充气是否是进化变化的适当和信息标记。首先，将完成四种现存非洲猿类和人类的成年颞骨气化形态学的比较分析。其次，将研究现代人颞骨充气的生长相关变化。第三，将分析现存和化石人科物种颞骨气化的进化变化。对于第一个和第二个目标，一些参数，如表面积，骨体积分数和各向异性，或骨方向性，将在高分辨率计算机断层扫描中测量，这些扫描来自成人个体和人类的横断面生长系列。第三个目标将使用先前从化石物种、现存非洲猿和现代人类中获得的低分辨率扫描来完成。这些分析将为古人类颞骨充气的生长相关和进化变化提供独特而重要的信息，并研究颞骨充气与颅骨明确的进化变化（如颅底屈曲和脑容量增加）之间的潜在相关性。本研究将为定量分析古人类颅骨充气现象提供一种新的方法。这种方法对脊椎动物颅骨充气空间的定量评估有很大的希望。在研究过程中获得的高分辨率计算机断层扫描将通过建立图像档案分发给更大的科学界，鼓励研究颞骨、耳朵和气化的科学家之间的合作工作。此处未研究的颞骨方面，如生理、听力和平衡，可以使用这些图像进行研究。这项研究还将鼓励人类学和生物医学研究人员之间的合作和互动，因为气化是这两个领域功能形态学和颞骨生理学的重要方面。最后，这个项目将促进研究生的教育和训练，为一个强大的，独立的研究生涯做准备。

This project will investigate evolutionary and growth-related changes in temporal bone pneumatization, the widespread process leading to air-filled cavities in adult temporal bones. Important conclusions regarding hominin phylogeny and craniofacial evolution have included temporal bone pneumatization as a phylogenetic, or species-specific, marker. Despite its previous inclusion in evolutionary analyses, a number of questions remain concerning the evolutionary and developmental changes in Homininae temporal bone pneumatization, as well as the developmental and functional basis for observed variation in pneumatization. The correct inclusion of this character in studies of human evolution requires a thorough understanding of the development and cause of temporal bone pneumatization, especially in correlation with other important traits showing evolutionary change. The proposed study will complete three objectives to determine if temporal bone pneumatization is an appropriate and informative marker for evolutionary change. First, a comparative analysis of adult morphology of temporal bone pneumatization in four living African ape and human species will be completed. Second, growth-related changes in temporal bone pneumatization in modern humans will be investigated. Third, evolutionary changes in temporal bone pneumatization in both living and fossil Homininae species will be analyzed. For the first and second objectives, a number of parameters, such as surface area, bone volume fraction, and anisotropy, or bone directionality, will be measured in high resolution computed tomography scans acquired from adult individuals and a cross-sectional growth series of humans. The third objective will be completed using low resolution scans previously acquired from fossil species, extant African apes, and modern humans. The proposed analyses will provide unique and important information about growth-related and evolutionary changes in temporal bone pneumatization in Homininae, and investigate potential correlations between temporal bone pneumatization and well-defined evolutionary changes in the skull, such as basicranial flexion and increased brain size. The proposed study will develop a novel approach for quantitatively analyzing pneumatization in Homininae skulls. This approach holds great promise for the quantitative assessment of pneumatized spaces in vertebrate skulls. High resolution computed tomography scans acquired during the course of the study will be distributed to the larger scientific community through the establishment of an image archive, encouraging collaborative work among scientists studying the temporal bone, the ear, and pneumatization. Aspects of the temporal bone not investigated here, e.g., physiology, hearing and balance, can be studied using these images. This study will also encourage collaboration and interaction between anthropological and biomedical researchers, as pneumatization is an important aspect of functional morphology and temporal bone physiology for both fields. Finally, this project will advance the education and training of a graduate student in preparation for a strong, independent research career.