Doctoral Dissertation Improvement: Hominid Forefoot Kinematics, Kinetics, and Bone Architecture

习惯的两足行走——只用两条腿走路——是人类的一种步态，而其他所有现存的灵长类动物，甚至是它们的近亲，非洲和亚洲的类人猿，都没有这种步态。传统上，关于最早的人类祖先（古人类）步态的争论集中在对下肢结构的解释上。迄今为止使用的方法已被证明是不确定的，特别是关于前足结构的功能含义。由于缺乏关于人类和类人猿（原始人）步态中前脚功能的数据，以及功能差异与足部结构的关系，这一问题进一步复杂化。本论文将对现存古人类第1 -3跖趾关节（MTPJ）的三维骨小梁（海绵状）结构进行量化，并测量MTPJ角度（运动学）和相应的足底压力（动力学），以检验关于古人类运动机制的假设。小梁骨在生命过程中对机械需求的反应非常灵敏，因此提供了一种新的方法来检验化石中关于关节功能长期未解决的假设。将记录黑猩猩（Pan troglodytes），倭黑猩猩（Pan paniscus）和人类在步态周期中的关键点的前足运动学和动力学。本研究将确定小梁骨结构是否可以通过关节姿势和负荷制度来区分物种。这种方法将用于评估早期古人类是否拥有类似现代人的脚趾脱落机制。这项研究的总体目标是帮助解决目前关于早期人类运动机制的争论，并提供对人类和现代人类两足动物进化的更好理解。拟议的研究有几个广泛的影响。首先，这个项目的结果将与所有研究形式和功能关系的脊椎动物形态学家相关。该项目还将鼓励跨学科研究，允许一名女博士生在美国和比利时科学家的指导下接受体质人类学和生物力学技术的培训。

Habitual bipedalism - walking exclusively on two legs - is a form of gait practiced by humans to the exclusion of all other living primates, even their closest relatives, the African and Asian great apes. Traditionally, debates over the gait of the earliest human ancestors (hominins) have centered on the interpretation of lower limb structure. The methods used to date have proved to be inconclusive, especially regarding the functional implications of the structure of the forefoot. This problem is further compounded by a lack of data on how the forefoot function during gait in living humans and great apes (hominids), and how differences in function relate to foot structure.The proposed dissertation research will quantify the three-dimensional trabecular (spongy) bone structure at the 1st-3rd metatarsophalangeal joints (MTPJ) and measure MTPJ angles (kinematics) and respective plantar pressures (kinetics) in living hominids in order to test hypotheses about the locomotor regimes of fossil hominins. Trabecular bone is highly responsive to mechanical demand during life and therefore offers a new approach to test hypotheses that have long remained unresolved about joint function in fossils. Forefoot kinematics and kinetics will be documented for chimpanzees (Pan troglodytes), bonobos (Pan paniscus), and humans at key points during the gait cycle. This study will determine whether trabecular bone structure can differentiate species by joint postures and loading regimes. This approach will then be used to assess whether early hominins possessed a modern human-like toe-off mechanism. The overarching goals of this research are to help resolve current debates about early hominin locomotor regimes and provide a better understanding of the evolution of hominin and modern human bipedalism.The proposed research has several broad impacts. First, the results of this project will be relevant to all vertebrate morphologists studying form and function relationships. This project will also encourage interdisciplinary research by allowing a female doctoral student to be trained in techniques of physical anthropology and biomechanics under the guidance of both American and Belgian scientists.