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

该项目支持对墨西哥裔美国博士后的培训和教育，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。作为一名奇卡纳和第一代大学毕业生，这位研究员个人致力于扩大STEM领域中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能力。用两条腿走路是人类血统的一个决定性特征，但关于人类步态的起源和进化仍然存在重大问题。两足动物在人类谱系中很早就进化了，可能早在600万年前；然而，关于最早的原始人是否基本上像今天的现代人一样行走，或者不同的原始人物种在步态生物力学方面是否有所不同，这一问题一直存在重大争论。最近发现了一具异常完整的200万年前的南方古猿源泉骨骼，这激发了人们对原始人下肢的发育和功能的新探索。尤其是最近对Au的解释。关于不同种类的南方古猿在两足动物的形式上可能有何不同，源泉重新点燃了这场辩论。直接验证这些假说的唯一方法依赖于检查骨骼的各个方面，这些方面对生长过程中的生物力学要求很敏感，从而为生长过程中步态的生物力学提供证据。然而，目前人们对步态生物力学如何影响下肢发育知之甚少。这个项目结合了实验、个体发生和比较的方法来解释和重建早期的原始人两足动物。首先，在一个小鼠的实验模型中，研究了不同的运动方式(垂直攀爬、脚踏式抓冠攀登和车轮奔跑)对小腿形态的影响，以解决股骨和胫骨的骨骼可塑性问题。在这个项目的运作中，这位同事通过GWU的少数民族学生组织，如Bouchet Society，招募少数民族学生接受助理研究人员的培训。这位研究员继续通过面向对科学感兴趣的低收入和少数族裔学生的外展项目向儿童展示她的研究。这有赖于以前在研究生院试行的适合年龄的活动的实施经验。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联计划(例如，科学家在，今天的人类起源(热点)主题)吸引广大受众，这些计划基于最初在她论文最后一年为北卡罗来纳自然科学博物馆设计的演示文稿。这位研究员继续活跃在科学研究生女性项目中，支持STEM领域的其他女性科学家，并为这些女性协调外展和志愿者机会。智力优势：拟议的项目促进了我们对现代直立两足步态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，该项目有可能改变古人类学目前的范式，并整合实验、发育和比较数据，以实现对人类膝关节解剖功能意义的更严格理解。实验部分为解释一项全面的个体发育灵长类比较研究的结果提供了背景，该研究检查了发育轨迹是否与整个发育过程中的行为变化相关，并解决了偏离一般哺乳动物和灵长类骨骺融合模式是否与特殊运动相关。最后，包括属于早期直立人和其他早期人种的腿部化石，以根据上述实验和个体发育结果检验和提出关于发育形态的功能意义的假设。

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.