Pelvic Shape and Differential Mortality: Obstetric Variation Among Indigenous North American Populations

本研究考察了骨盆尺寸与自然选择的关系，因为它与女性死亡年龄和过去北美土著群体的气候有关。研究人员预测，女性狭窄的骨盆入口（产科效率的衡量标准（分娩无并发症的能力））将导致年轻个体的更高死亡率。此外，先前的研究已经将骨盆形状，特别是臀部宽度，与体温调节联系起来。身体较宽的个体相对于身体质量的表面积较小，因此能更有效地保持身体热量。研究表明，北美土著居民的身体比他们所生活的纬度地区的人要宽。因此，他们的体型可能与共同的祖先居住在较冷的气候有关，这一特征后来被后代所共有。虽然气候可能在温暖的气候中选择了较窄的身体，但产科效率可能减轻了这种压力。尽管有多种因素与个体死亡的年龄有关，但年轻平均死亡率与盆腔出口狭窄之间的相关性支持盆腔形状和产科并发症作为女性的选择性因素。此外，如果骨盆出口的形状与髋总宽度共同变化，这将表明骨盆形状确实是至少两种选择压力之间的平衡：气候和产科。从广义上讲，这个项目有助于理解迁徙人类所遇到的生物变化和影响这些变化的因素。它有助于进一步了解人类体型的变化。该研究将包括博士前学生在主要骨骼库的数据收集，并鼓励学生进一步研究的发展。此外，与莱比锡马克斯普朗克研究所的一名博士后研究员合作开发的捕捉和比较形状数据的新方法将被创造出来并与其他研究人员分享。

This research examines the association of pelvic dimensions and natural selection as it relates to both age-at-death in females and climate among past indigenous North American groups. The investigators predict that narrow pelvic inlets in females, a measure of obstetric efficiency (the ability to give birth without complications) will have caused higher death rates in young aged individuals. In addition, previous studies have linked pelvic shape, especially hip breadth, to body heat regulation. Individuals with wider bodies have less surface area relative to body mass, and therefore are more efficient at retaining body heat. Indigenous North Americans have been shown to possess wider bodies than would be expected for the latitudes in which they lived. Thus, their body shape may be related to common ancestral occupation of colder climates, a trait then shared by descendent populations. Although climate may have selected for narrower bodies in warmer climates, obstetric efficiency may have attenuated this pressure. Although multiple factors are related to the age at which individuals died, a correlation between young aged mean mortality and narrow dimensions in the pelvic outlet would support pelvic shape and obstetrical complications as a selective factor among females. Furthermore, if the shape of the pelvic outlet covaries with overall hip breadth, this would indicate that pelvic shape is indeed a balance between at least two selective pressures: climate and obstetrics.Broadly, this project contributes to the understanding of biological changes encountered by migrating humans and factors influencing those changes. It contributes further to an understanding of body shape variation among humans. The study will incorporate pre-doctoral students in data collection at major skeletal repositories and encourages students toward the development of further studies. Furthermore, new methods for capturing and comparing shape data, developed in collaboration with a postdoctoral researcher at the Max Planck Institute in Leipzig, will be created and shared with other researchers.