Doctoral Dissertation Improvement: Can Long Bone Cross-Sectional Properties Reliably Reveal Interpopulation Genetic Distance?

过去人类的骨骼遗骸为人类形态的进化提供了宝贵的窗口，并增强了对现代人类形态功能变异的理解，部分原因是古代人类的行为范围比今天所看到的更为多样。肢体骨骼在这方面尤其重要，因为它们通过一个称为骨骼功能适应（BFA）的过程对身体活动做出动态反应。因此，手臂和腿骨通常被视为“行为代理”，提供有关过去人口的移动性，生活方式变化和技术创新的关键信息。然而，有证据表明，BFA是在某种遗传控制下调节骨对机械环境的敏感性。因此，长骨结构和相关功能的变化可能反映了遗传祖先，就像行为一样。骨盆和头骨根据遗传预期而变化，因此可以反映人口历史的重要方面（例如，迁移、分化或人口减少）。博士生Gina Agostini（在马萨诸塞州阿默斯特大学Brigitte Holt博士的指导下）推动这篇论文研究的主要问题是长骨是否也是如此，这个问题需要通过比较欧洲人群及其南非后裔之间的颅骨和长骨变异模式来回答。使用卡尺测量和数字化骨模型，收集每个人群的颅骨和长骨形状数据。将使用群体遗传学软件分析这些数据，以预测研究群体之间的遗传距离（关系）。如果长骨确实反映了遗传变异，那么由长骨形状产生的关系通常应该与颅骨产生的关系相匹配。如果它们不匹配，这表明颅骨和长骨主要反映了不同的生物或环境过程。结果将提倡使用长骨推断人口历史的新用途，或将加强其在辨别行为（或其他环境刺激）方面的实用性，澄清长骨是否主要反映遗传或行为信号对于必须从有限的骨骼数据中提取信息的人类起源研究至关重要。此外，由于BFA是调节骨骼可塑性，维护和愈合的同一过程，因此该项目将显示我们的祖先是否会影响我们骨骼对新运动制度，运动或骨折的反应时间。这项研究也支持公众对祖先的兴趣日益增长，商业祖先工具包和家谱程序的广泛流行证明了这一趋势。除了公开访问的报告，该项目产生的数据将被整合到一系列以社区为基础的讲座，社交媒体互动，公共研讨会和终身学习的机会已经由研究人员进行。

Skeletal remains of past human populations provide invaluable windows onto the evolution of human morphology, as well as enhanced understanding of functional variation in modern human morphology, in part because the range of behavior in ancient humans was more varied than is seen today. Limb bones are especially important in this respect, as they dynamically respond to physical activity via a process called bone functional adaptation, or "BFA." As a result, arm and leg bones are often treated as a "behavioral proxies" that provide critical information about mobility, lifestyle change, and technological innovation in past populations. Evidence shows, however, that BFA is under some genetic control that regulates bone sensitivity to mechanical environment. Variation in long bone structure and associated function therefore may reflect genetic ancestry, as much as behavior. The pelvis and skull vary in accordance with genetic expectations and can therefore reflect important aspects of population history (e.g., migration, divergence or population reduction). The primary question driving this dissertation research by doctoral student Gina Agostini (under the supervision of Dr. Brigitte Holt, University of Massachusetts Amherst) is whether the same is true of long bones, a question to be answered by comparing patterns of cranial and long bone variation among European populations and their South African descendants. Using caliper measurements and digitized bone casts, data will be collected on cranial and long bone shape for each population. These data will be analyzed using population genetics software to predict the genetic distances (relationships) among the populations under study. If long bones do reflect genetic variation, then the relationships produced by long bone shape should generally match those produced by the crania. If they do not match, this suggests that cranial and long bones primarily reflect different biological or environmental processes. Results will either advocate the novel use of long bones to infer population history or will reinforce their usefulness at discerning behavior (or other environmental stimuli).Clarification as to whether long bones primarily reflect genetic or behavioral signals is crucial for studies of human origins which must routinely extract information from limited skeletal data. Furthermore, because BFA is the same process that regulates bone plasticity, maintenance and healing, this project will show whether our ancestry influences the response time of our bones to a new exercise regime, sport, or fracture. This research also supports growing public interest in ancestry, a trend evidenced by the wide popularity of commercial ancestry kits and genealogical programs. In addition to publicly accessible reports, data generated by this project will be integrated into a series of community-based lectures, social media interactions, public workshops, and lifelong learning opportunities already conducted by the researchers.