Doctoral Dissertation Research: The evolution of early hominin locomotor anatomy

两足行走是习惯性地用两条腿站立和直立行走的能力，是人类的定义特征之一。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有关已灭绝人类物种“家谱”的信息来重建对两足行走至关重要的骨骼特征如何、何时以及为何进化。这种重建使项目调查人员能够测试有关人类起源的关键假设，包括那些关于环境因素在塑造我们的进化历史中可能发挥的作用的假设。这项研究调查了生态条件如何影响人类进化，这一调查在全球气候变化的背景下尤为重要。该项目还支持了一位早期职业女性科学家的研究，她来自一个在STEM领域历史上代表性不足的群体，并为生物人类学的学术多样性做出了贡献。该研究测试了两个假设，这些假设将性格进化的模式与人类两足行走的骨骼特征进化的生态、时间和地理背景联系起来。第一个假设涉及两足动物起源和随后演变的模式和过程，以及可能塑造其演变的选择性历史。第二个假设涉及是否派生的运动性状的演变与古环境变化的时间相关，是否将现有的古环境数据改进进化模型。使用最大简约和贝叶斯推理的字符演变模式进行了分析。随机和非随机的进化模型进行测试，以检查哪种模型是最适合解释人类运动解剖的进化。该项目有助于回答古人类学中的几个基本问题：胚胎发育如何告知我们对两足动物机械功能的颅后特征的进化的理解？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？是什么样的进化力量推动了这些角色的进化？什么是增强两足行走的形态特征变化的幅度和方向？两足动物特征的变化与环境的变化有什么关系？对这些问题的回答充分地告知了我们对最早也是最基本的人类适应之一的进化的理解。这个奖项反映了NSF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.