Doctoral Dissertation Research: Ontogeny, Evolution, and Ecogeographic Patterns of Human Limb Morphology

现代人几乎扩展到世界上的每一个地区，在文化和生物上都适应了一系列的自然环境。过去对人类骨骼生物学的研究表明，在冷适应人群中，人类肢体骨骼向更短、更健壮的形态转变，而在热适应人群中，人类肢体骨骼向更高、更不健壮的形态转变。这个博士论文项目将研究进化过程如何通过生长和发育(个体发育)的变化来塑造人类肢体骨骼的这种多样性。该项目将直接解决不同进化力量与生长轨迹变化之间的关系，促进对支撑人类形态适应和可塑性的生物机制的了解。由CT扫描重建的3D表面效果图和该项目产生的其他数据将免费共享，以促进进一步的研究和在线教学材料的开发。此外，该项目将通过与伙伴机构的会议、研讨会和研讨会促进本科生的指导和培训，以及国内和国际合作。过去的研究表明，通过自然选择适应气候条件，中性(非选择性)进化，以及因气候条件而产生的不可遗传的变化(表型可塑性)，都可能在形成人类四肢骨骼中观察到的各种形态模式方面发挥重要作用。此外，对幼年骨骼的研究表明，这些形态模式在年轻时就很明显。这些不同的进化力量在生长过程中何时以及如何影响肢体的形状和大小仍不清楚。该项目使用从考古人群的骨骼样本中获取的全球骨测量样本和从当代人群的CT扫描重建的3D模块来梳理这些不同的进化力量。研究人员将使用一系列统计方法和模型来解决以下问题：1)在生长过程中对身体大小的选择是否会对肢体形态产生不同的影响，2)中性进化力量除了气候适应外，还可以解释生长轨迹的一些差异，以及3)选择主要影响成年人、青少年个人或两者。这一奖项反映了NSF的法定使命，并通过使用基金会的智力优势和更广泛的影响审查标准进行评估，被认为值得支持。

Modern humans expanded into nearly every region of the world, adapting both culturally and biologically to a range of natural environments. Past research in human skeletal biology has shown that the human limb skeleton shifts toward a shorter, more robust morphology in cold-adapted populations and a taller, less robust morphology in heat-adapted populations. This doctoral dissertation project will examine how evolutionary processes have shaped this diversity in the human limb skeleton through changes in growth and development (ontogeny). The project will directly address the relationship between different evolutionary forces and changes in growth trajectories, advancing knowledge about biological mechanisms underpinning human morphological adaptations and plasticity. Reconstructed 3D surface renderings from computed tomography (CT) scans and other data generated from this project will be shared freely to facilitate further research and the development of online teaching materials. In addition, the project will promote undergraduate mentoring and training, as well as national and international collaborations through conferences, seminars and workshops with partner institutions.Past studies have shown that adaptation by natural selection to climatic conditions, neutral (non-selective) evolution, and non-heritable change in response to climatic conditions (phenotypic plasticity) may all play important roles in shaping the diverse morphological patterns observed in the human limb skeleton. In addition, studies on juvenile skeletons have shown that these morphological patterns are evident at young ages. When and how these different evolutionary forces influence limb shape and size during growth remain unclear. This project uses a global sample of osteometric measurements taken from bone specimens of archaeological populations and 3D modules reconstructed from CT scans of contemporary population to tease apart these different evolutionary forces. The investigator will use a range of statistical methods and models to address whether: 1) selection on body size during growth will have different effects on limb morphology, 2) neutral evolutionary forces can account for some of the divergence in growth trajectories in addition to climatic adaptation, and 3) selection acts primarily on adults, juvenile individuals, or both.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.