Trabecular Bone Morphology and Locomotion in Extant Primates and Fossil Hominins

本项目开发了一种新的方法来重建步态和化石中其他方面的行为，并扩大了我们对解剖关节结构和功能之间关系的理解。关于早期人类化石步态的两个主要争论是：(1)他们的两足直立行走步态的性质（它是现代人类的步态还是弯曲的臀部和膝盖）；(2)在树上攀爬和移动是否仍然是这些早期物种生态行为的重要组成部分。在过去的十年里，许多研究人员已经承认，这些争论已经陷入了僵局，要想解决这个问题，就需要关于生命中功能活动的化石证据的新类型的数据。成像和分析技术的进步现在允许研究人员捕捉和量化化石中骨小梁的三维（3D）结构——对载荷历史最敏感的骨组织——并提供生命过程中关节载荷的各种证据，以打破这一僵局。本研究的主要目的是研究高等灵长类动物的三维骨小梁结构与掌骨（手）和股骨（髋关节和膝关节）关节功能之间的关系。更具体地说，本研究旨在(1)建立不同步态的现代高等灵长类动物的骨小梁结构与习惯性关节姿势之间的关系（例如，涉及更多弯曲或伸展的关节）；(2)检查关节的骨小梁特征与骨轴的横截面强度之间的关系。建立习惯性关节功能与关节内小梁骨结构之间关系的本质，将使研究人员能够更准确地重建化石物种的步态。这个项目将把它的发现应用于一个关于化石功能行为的假设，即尼安德特人使用他们的手的方式是否与现代人不同。这项研究是迄今为止对高等灵长类动物骨小梁结构最全面的分析。这项研究也有几个重要的更广泛的影响。在这项研究中获得的扫描将公开，以促进进一步的研究。至少有一名博士生将从该项目中获得培训。这将有助于发展一种行为重建的新方法，这将引起人类学以外的古生物学家的兴趣。最后，该提案将促进一位地质学家和两位体质人类学家之间的跨学科研究，以及美国和日本研究人员之间的国际合作。

This project develops a new approach to reconstructing gait and other aspects of behavior in fossils, and expands our understanding of the relationship between anatomical joint structure and function. The two main debates concerning gait in early fossil humans are over (1) the nature of their bipedal, upright walking gait (whether it was modern human-like or a gait with bent hips and knees), and (2) whether or not climbing and moving in trees remained an important part of the ecological behavior of these early species. Over the last decade, many researchers have acknowledged that these debates have reached an impasse, and that a resolution will require new kinds of data regarding fossil evidence of functional activity during life. Advances in imaging and analysis now permit researchers to capture and quantify the three dimensional (3D) structure of trabecular bone - the bone tissue most sensitive to loading history - in fossils and provide the kinds of evidence of joint loading during life needed to move beyond this impasse. The primary goals of this research are to examine the relationships between 3D trabecular structure and metacarpal (hand) and femoral (hip and knee) joint functions in higher primates. More specifically, this research aims to (1) establish the relationships between trabecular bone architecture and habitual joint posture in modern higher primates that differ in their manner of gait (e.g., involving more flexed or extended joints), (2) examine the relationships between trabecular bone characteristics of the joint and cross-sectional strength of the bone shaft. Establishing the nature of the relationship between habitual joint function and the structure of trabecular bone within the joint will then allow researchers to more accurately reconstruct gait in fossil species. This project will apply its findings to one hypothesis about functional behavior in fossils, namely whether Neanderthals used their hands in ways that differed from those of modern humans. This research entails the most comprehensive analysis to date of higher primate trabecular bone structure. This research also has several important broader impacts. The scans obtained in this research will be made publicly available to foster additional research. At least one doctoral student will gain training from this project. It will help to develop a new approach to behavioral reconstruction that will be of interest to paleontologists outside of anthropology. Finally, this proposal will foster interdisciplinary research between a geologist and two physical anthropologists, and international collaboration between researchers in the U.S. and Japan.