Experimental approaches to understanding the evolution of human phenotypic diversity

了解人类表型多样性进化的实验方法

• 批准号: RGPIN-2021-02442
• 负责人: Murray, Alison
• 金额: $ 2.04万
• 依托单位: University of Victoria
• 依托单位国家: 加拿大
• 项目类别: Discovery Grants Program - Individual
• 财政年份: 2021
• 资助国家: 加拿大
• 起止时间: 2021-01-01 至 2022-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=741980
• 关键词: Experimental; approaches; understanding; evolution; human

Modern humans vary in observable characteristics (phenotype) like body size/breadth, limb proportions, body composition, and musculoskeletal traits, yet we are all extremely genetically similar, creating a compelling paradox of particular interest for understanding human evolutionary history. The key to unlocking this paradox is in understanding the mechanisms shaping human plasticity; plasticity is the keystone of the human adaptive response, allowing phenotype to be sensitively adjusted to environmental stresses much faster than is possible through genetic adaptation alone. Some of these stresses stem from balancing the costs of locomotion and thermoregulation in a given environment, both being energetically expensive functions that are critical for survival. Biological anthropologists traditionally use simple models to link phenotypic variation to locomotor costs when moving over flat, open terrain and thermoregulatory costs at rest. However, global patterns do not always match what would be expected based on these simple models. In reality, selection pressures shaping locomotor morphology are complex and vary in relation to multiple environmental factors like vegetation and terrain, and sex-specific factors like the costs of reproduction and load-carrying; none of these have been adequately incorporated into the biomechanical and energetic models on which biological anthropology has traditionally relied. My proposed research represents a transformative new approach to understanding how locomotor and energetic selection pressures have shaped modern human diversity and sexual dimorphism. This work combines engineering-based musculoskeletal modelling with laboratory- and field-based experimental analyses with athletes in order to: i) directly test sex-specific relationships between human phenotypic variation, locomotor costs, and gait kinematics in different environmental conditions, ii) computationally model whether or not variation in skeletal traits typically used to infer behavioural differences between past populations actually produces meaningful adaptive kinematic benefits, and iii) test the extent to which prolonged locomotion-related energetic stress may have contributed to the evolution of sex differences in body composition. In doing so, I will directly link sex-specific phenotypic variation with its kinematic and energetic consequences and offer unprecedented insight into how modern human diversity has been shaped by the environments in which we have lived, moved, and adapted.  The proposed research will also provide crucial sex-disaggregated data to fields in which females are often underrepresented in research. Further, the custom computer modelling methods developed and real-time motion data collected will enable the construction of gait simulations that better incorporate inter-individual variation and help inform the design of customized assistive solutions for individuals with physical and/or locomotor challenges.

现代人在可观察到的特征(表型)上有所不同，如身体大小/宽度、肢体比例、身体成分和肌肉骨骼特征，但我们在基因上都非常相似，这创造了一个引人注目的悖论，尤其对理解人类进化史特别感兴趣。解开这一悖论的关键是理解塑造人类可塑性的机制；可塑性是人类适应反应的基石，使表型能够以比仅通过遗传适应更快的速度敏感地适应环境压力。其中一些压力来自于在特定环境中平衡运动和体温调节的成本，这两者都是对生存至关重要的能量昂贵的功能。生物人类学家传统上使用简单的模型，将表型变化与在平坦开阔的地形上移动时的运动成本和静止时的体温调节成本联系起来。然而，全球模式并不总是与基于这些简单模型的预期相符。在现实中，影响运动形态的选择压力是复杂的，而且与多种环境因素有关，如植被和地形，以及特定性别的因素，如繁殖和负重的成本；这些都没有被充分纳入生物人类学传统上所依赖的生物力学和能量模型中。我提出的研究代表了一种变革性的新方法，可以理解运动和精力充沛的选择压力是如何塑造现代人的多样性和性别二态的。这项工作将基于工程的肌肉骨骼建模与基于实验室和现场的运动员实验分析相结合，以：i)直接测试不同环境条件下人类表型变异、运动成本和步态运动学之间的性别特定关系，ii)计算模拟用于推断过去人群之间行为差异的骨骼特征的变化是否真的产生有意义的适应性运动学益处，以及iii)测试与运动相关的长期能量应激在多大程度上可能有助于身体成分的性别差异的进化。通过这样做，我将直接将特定性别的表型变异与其运动学和能量后果联系起来，并提供前所未有的洞察力，了解我们生活、移动和适应的环境是如何塑造现代人类多样性的。拟议中的研究还将为女性在研究中往往代表不足的领域提供关键的性别分类数据。此外，开发的定制计算机建模方法和收集的实时运动数据将使步态模拟能够更好地结合个体之间的差异，并有助于为有身体和/或运动挑战的个人设计定制的辅助解决方案。