Human skeletal variation: adaptive responses during growth of the bony pelvis

人类骨骼变异：骨盆生长过程中的适应性反应

• 批准号: RGPGP-2014-00054
• 负责人: Kurki, Helen
• 金额: $ 1.75万
• 依托单位: University of Victoria
• 依托单位国家: 加拿大
• 项目类别: Discovery Grants Program - Group
• 财政年份: 2014
• 资助国家: 加拿大
• 起止时间: 2014-01-01 至 2015-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=565939
• 关键词: Human; skeletal; variation; adaptive; responses

Evolutionary explanation of the difficulty and risk to the mother and newborn associated with human childbirth have focused on the close fit between the size of the maternal pelvis and the size of the newborn as resulting from our distinctive method of walking on two legs and our large brains. This “obstetric dilemma” views female pelvic form as a compromise between the mechanical requirements of bipedalism for a narrow pelvis and the obstetric requirements for a roomy pelvic canal for our large-brained babies, resulting in strong selective pressures acting on the female pelvis among humans and over our evolutionary history. Physical variation within a population or species can be limited by such competing selective processes (as predicted by the obstetric dilemma hypothesis), yet morphology is also influenced by environmental stimuli acting during growth and development, through biological plasticity. For the pelvis these stimuli may include gait, activity levels and technological means of mitigating activity, diet, and health. Plastic responses generate variation among individuals and populations in anatomy and physiology. Hence, the cultural production of the human skeleton provides bioarchaeologists a window on the activities and adaptations of past populations. Medical models have tended to view both childbirth and female pelvic form in a typological framework, with variation from certain norms as increasing risk of obstructed labour. However, recent studies have shown significant variation among and within human populations in pelvic canal shape and capacity. Further, historical preconceptions of an “obstetric dilemma” may actually be the result of differential plasticity between the maternal pelvis and newborn size, in changing cultural environments. Under this model, human ecological and cultural changes may play a particular role in determining pelvic form. Yet, little research has to date examined the factors that influence pelvic growth and development. Human skeletal remains of juveniles from varied and well-documented archaeological contexts provide an opportunity to study factors influencing growth and development in specific ecological contexts (e.g., subsistence, technologies, and geographical location). In order to understand the potential role of biological plasticity in shaping the maternal pelvis, we ask: when and why does variation in pelvic forms arise, and what role does biological plasticity play in generating variation in relation to environmental stimuli? This study will use three-dimensional (3D) approaches to studying the form of juvenile and adult human pelvic bones from diverse skeletal samples to investigate the relationships among ecological and cultural attributes of populations and pelvic growth and development. This represents a novel approach to examining growth and development of the pelvis and the selective and plastic factors that produce morphological variation among human populations. Understanding the interplay between plasticity and constraint (evolutionary, functional, or developmental) in the generation of morphological variation aids in identifying environmental factors (climatic, ecological, cultural) that influence adaptation. These are of particular importance to evolutionary anthropologists, paleoanthropologists, and evolutionary anatomists. This patterning of human pelvic variation is also essential for understanding modern medical problems such as cephalo-pelvic disproportion and obstructed labour. An awareness of adaptive responses and constraints is of importance for bioarchaeologists where the outcomes of growth processes are increasingly being employed as indicators of population health through time in response to demographic and ecological changes.

人类分娩对母亲和新生儿的困难和风险的进化解释集中在母亲骨盆的大小和新生儿的大小之间的紧密配合，这是由于我们独特的两条腿走路的方法和我们巨大的大脑。这种“产科困境”将女性骨盆的形状视为两足动物对狭窄骨盆的机械要求和我们大脑婴儿对宽敞骨盆管的产科要求之间的妥协，导致人类和我们进化历史中女性骨盆的强烈选择压力。一个种群或物种内的物理变异可能受到这种竞争性选择过程的限制（正如产科困境假说所预测的那样），但形态学也受到生长和发育过程中环境刺激的影响，通过生物可塑性。对于骨盆，这些刺激可能包括步态、活动水平和减轻活动的技术手段、饮食和健康。可塑性反应在个体和种群之间产生解剖学和生理学上的差异。因此，人类骨骼的文化生产为生物考古学家提供了一个了解过去人口活动和适应的窗口。医学模式倾向于在类型学框架中看待分娩和女性骨盆形状，与某些规范的差异增加了难产的风险。然而，最近的研究表明，在人群之间和人群内，骨盆腔的形状和容量存在显着差异。此外，“产科困境”的历史偏见实际上可能是在不断变化的文化环境中，母亲骨盆和新生儿大小之间的差异可塑性的结果。在这种模式下，人类生态和文化的变化可能在决定骨盆形状方面发挥特殊作用。然而，迄今为止，很少有研究探讨影响骨盆生长和发育的因素。来自各种有据可查的考古背景的青少年人类骨骼遗骸为研究在特定生态环境中影响生长和发育的因素提供了机会（例如，技术、地理位置）。为了了解生物可塑性在塑造母亲骨盆的潜在作用，我们问：什么时候以及为什么骨盆形状的变化出现，以及生物可塑性在产生与环境刺激有关的变化中起什么作用？本研究将使用三维（3D）方法来研究不同骨骼样本的青少年和成年人骨盆骨的形式，以调查种群的生态和文化属性与骨盆生长发育之间的关系。这代表了一种新的方法来检查骨盆的生长和发育，以及在人群中产生形态变异的选择性和可塑性因素。了解可塑性和约束（进化，功能，或发育）之间的相互作用，在形态变异的产生，有助于确定环境因素（气候，生态，文化）影响适应。这些对于进化人类学家、古人类学家和进化解剖学家来说特别重要。这种人类骨盆变异的模式对于理解现代医学问题，如头盆不称和难产也是必不可少的。适应性反应和限制的意识是生物考古学家的重要性，其中的增长过程的结果越来越多地被用来作为人口健康的指标，通过时间来应对人口和生态变化。