Doctoral Dissertation Research: The evolution of early hominin locomotor anatomy

两足行走是一种习惯直立行走的能力，是人类的特征之一。因此，我们对人类进化的理解取决于重建两足动物是如何以及为什么进化的。这个博士论文研究项目使用关于已灭绝人类物种“家谱”的信息来重建对两足动物至关重要的骨骼特征是如何、何时以及为什么进化的。这种重建使项目研究人员能够检验关于人类起源的关键假设，包括那些关于环境因素可能在塑造我们的进化史中所起作用的假设。这项研究调查了生态条件是如何影响人类进化的，这在全球气候变化的背景下是一个特别重要的研究方向。该项目还支持来自STEM历史上代表性不足群体的早期职业女性科学家的研究，并有助于生物人类学奖学金的多样性。本研究测试了两种假设，这些假设与人类两足动物的骨骼特征进化的生态、时间和地理背景有关。第一种假说阐述了两足动物起源和随后进化的模式和过程，以及可能影响其进化的选择性历史。第二种假说涉及运动特征的演化是否与古环境变化有时间相关性，以及是否将现有的古环境数据纳入进化模型。利用最大简约性和贝叶斯推理分析了特征演化模式。随机和非随机进化模型进行了测试，以检验哪种模型最适合解释人类运动解剖学的进化。该项目有助于回答古人类学中的几个基本问题：系统发育如何帮助我们理解在两足动物时期机械功能的后颅特征的进化？这些特征的进化模式告诉我们，在人类进化过程中，两足动物是如何、为什么以及何时进化的？推动这些角色进化的进化力量是什么？增强两足行走的形态特征变化的幅度和方向是什么？两足动物特征的变化与环境的变化有什么关系？这些问题的答案极大地告知了我们对人类最早也是最基本的适应性之一的进化的理解。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

Bipedalism is the ability to habitually stand and walk upright on two legs and is one of the defining features of humans. Consequently, our understanding of human evolution depends on reconstructing how and why bipedalism evolved. This doctoral dissertation research project uses information about the “family tree” of extinct human species to reconstruct how, when, and why skeletal features that are critical for bipedalism evolved. This reconstruction allows the project investigators to test key hypotheses about human origins, including those concerning the role that environmental factors may have played in shaping our evolutionary history. This study investigates how ecological conditions have influenced human evolution, a line of inquiry that is particularly important in the context of global climate change. This project also supports the research of an early career female scientist from an historically underrepresented group in STEM and contributes to the diversity of scholarship in Biological Anthropology.This research tests two hypotheses relating patterns of character evolution to the ecological, temporal, and geographical contexts in which skeletal traits related to hominin bipedalism evolved. The first hypothesis addresses the patterns and processes by which bipedalism originated and subsequently evolved, as well as the selective history that may have shaped its evolution. The second hypothesis concerns whether the evolution of derived locomotor traits is temporally correlated with paleoenvironmental change and whether incorporating available paleoenvironmental data improves evolutionary models. Patterns of character evolution are analyzed using maximum parsimony and Bayesian inference. Random and non-random evolutionary models are tested to examine which model is the most appropriate for explaining the evolution of hominin locomotor anatomy. The project helps answer several fundamental questions in paleoanthropology: How does phylogeny inform our understanding of the evolution of postcranial traits that function mechanically during bipedalism? What does the pattern of evolution for these traits tell us about how, why, and when bipedalism evolved during human evolution? What are the evolutionary forces driving the evolution of these characters? What are the magnitude and direction of changes in morphological characters that enhance bipedalism? How might changes in bipedal features relate to changes in the environment? Answers to these questions substantially inform our understanding of the evolution of one of the first and most fundamental hominin adaptations.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.