Functional Anatomy of the Knee and Development-Implications for Interpreting Early Hominin Locomotion

该项目支持墨西哥裔美国人博士后研究员的培训和教育，这是一个在科学，特别是古人类学方面代表性不足的少数民族。作为奇卡纳和第一代大学毕业生，研究员个人致力于扩大在干领域代表性不足的个人的参与。该研究项目探索人类的两足行走。用两条腿走路是人类谱系的一个定义性特征，但关于人类步态的起源和进化仍然存在重大问题。两足行走在人类谱系的早期就进化出来了，可能早在六百万年前;然而，关于最早的古人类是否基本上像今天的现代人类一样行走，或者各种古人类物种的步态生物力学是否不同，一直存在重大争论。最近发现的一具异常完整的、200万年前的南方古猿sediba骨架激发了对人类下肢发育和功能的新探索。特别是最近的解释Au。南方古猿的不同物种在两足行走的形式上可能存在差异，南方古猿sediba的研究为这一争论注入了新的活力。直接测试这些假设的唯一方法依赖于检查骨骼的各个方面对生长期间的生物力学需求敏感，从而提供生长期间步态生物力学的证据。然而，目前很少有人知道步态生物力学如何影响下肢的发展。该项目结合实验，个体发育和比较的方法来解释和重建早期人类两足行走。首先，在小鼠实验模型中研究运动机制（垂直攀爬、踏板抓握树冠攀爬和轮跑）对下肢形态的影响，解决股骨和胫骨的骨骼可塑性。在运行这个项目，研究员招募少数民族学生通过少数民族学生组织在GWU，如Bouchet社会培训为助理研究员。该研究员继续通过针对低收入和少数民族学生对科学感兴趣的外展计划向儿童介绍她的研究。这依赖于以前的经验，实施适合年龄的活动，在研究生院试点。提高公众对科学的理解的其他努力包括通过史密森学会国家自然历史博物馆的外展计划（例如，科学家是在，人类起源今天（热）的主题），基于演示文稿最初开发的自然科学的NC博物馆在她的论文的最后一年。该研究员继续积极参与研究生女性科学，支持STEM领域的其他女科学家，并为这些女性协调外展和志愿者机会。智力优势：拟议的项目推进了我们对直立双足步态现代风格如何以及何时演变的理解。目前的范式认为所有早期人类祖先和亲属在本质上是相同的，而事实上，在人类进化的早期阶段可能存在相当大的适应性多样性。因此，该项目有可能改变目前的古人类学范式，并整合实验，发育和比较数据，以实现对人类膝关节解剖学功能意义的更严格理解。实验部分提供的背景下，解释一个全面的个体发育灵长类动物的比较研究，研究是否发育轨迹与整个发展过程中的行为变化相关的结果，并解决是否偏离一般的哺乳动物和灵长类动物的骨骺融合模式与专门的运动。最后，下肢化石属于早期直立人和其他早期人类物种的测试和推进假设的功能意义的发展形态，根据上述实验和个体发育的结果。

This project supports the training and education of a Mexican American Postdoctoral Fellow, an under-represented minority in science and especially paleoanthropology. As a Chicana and first generation college graduate, the Fellow is personally committed to broadening participation of under-represented individuals in STEM fields. The research project explores bipedalism in humans. Walking on two legs is a defining feature of the human lineage, and yet major questions remain about the origin and evolution of human gait. Bipedalism evolved early in the human lineage, possibly as early as six million years ago; however, major debate has persisted over whether the earliest hominins walked essentially like modern humans do today, or whether various hominin species differ in their gait biomechanics. The recent discovery of an unusually complete, 2 million year old skeleton belonging to Australopithecus sediba has inspired new inquiry into the development and function of the hominin lower limb. In particular, recent interpretations of Au. sediba have refueled the debate as to how different species of australopiths may have varied in their form of bipedalism. The only way to directly test those hypotheses relies on examining aspects of the skeleton are sensitive to biomechanical demands during growth, and thus provide evidence of the biomechanics of gait during growth. However, little is currently known about how gait biomechanics influences the development of the lower limb. This project combines experimental, ontogenetic, and comparative approaches to interpret and reconstruct early hominin bipedalism. First, the effect of locomotor regimes (vertical climbing, pedal grasping canopy climbing, and wheel-running) on lower limb morphology are studied in a mouse experimental model, addressing skeletal plasticity of the femur and tibia. In running this project, the Fellow recruits minority students to be trained as assistant researchers through minority student organizations at GWU such as the Bouchet Society. The Fellow continues to present her research to children through outreach programs targeting low-income and minority students interested in science. This relies on previous experiences implementing age-appropriate activities, piloted during graduate school. Other efforts to improve public understanding of science include engaging broad audiences through the Smithsonian Institution's National Museum of Natural History's outreach programs (e.g., Scientist Is In, Human Origins Today (HOT) Topics), based on presentations originally developed for the NC Museum of Natural Sciences during the final year of her dissertation. The Fellow continues to be active in Graduate Women in Science, supporting other female scientists across STEM fields as well as coordinating outreach and volunteer opportunities for these women.Intellectual Merit: The proposed project advances our understanding of how and when our modern style of upright, bipedal gait evolved. The current paradigm views all early human ancestors and relatives as essentially the same, when in fact there may be considerable adaptive diversity in the early phase of human evolution. This project therefore has the potential to transform the current paradigm in paleoanthropology, and integrates experimental, developmental, and comparative data to achieve a more rigorous understanding of the functional significance of knee anatomy in humans. The experimental component provides the context for interpreting the results of a comprehensive ontogenetic primate comparative study, which examines whether developmental trajectories are correlated with behavioral changes throughout development, and addresses whether deviations from the general mammalian and primate pattern of epiphyseal fusion are correlated with specialized locomotion. Finally, lower limb fossils belonging to early Homo erectus and other early hominin species are included to test and advance hypotheses about the functional significance of developing morphology in light of the aforementioned experimental and ontogenetic results.