Betti Lia, von Cramon-Taubadel Noreen, Manica Andrea, Lycett Stephen J
Division of Biological Anthropology, Department of Archaeology and Anthropology, University of Cambridge, Cambridge CB2 3QG, UK.
Department of Anthropology, University at Buffalo, SUNY, Buffalo, New York 14261-0005, USA.
J Hum Evol. 2014 Aug;73:64-74. doi: 10.1016/j.jhevol.2014.02.021. Epub 2014 Jun 13.
Differences in the breadth of the pelvis among modern human populations and among extinct hominin species have often been interpreted in the light of thermoregulatory adaptation, whereby a larger pelvic girdle would help preserve body temperature in cold environments while a narrower pelvis would help dissipate heat in tropical climates. There is, however, a theoretical problem in interpreting a pattern of variation as evidence of selection without first accounting for the effects of neutral evolutionary processes (i.e., mutation, genetic drift and migration). Here, we analyse 3D configurations of 27 landmarks on the os coxae of 1494 modern human individuals representing 30 male and 23 female populations from five continents and a range of climatic conditions. We test for the effects of climate on the size and shape of the pelvic bone, while explicitly accounting for population history (i.e., geographically-mediated gene flow and genetic drift). We find that neutral processes account for a substantial proportion of shape variance in the human os coxae in both sexes. Beyond the neutral pattern due to population history, temperature is a significant predictor of shape and size variation in the os coxae, at least in males. The effect of climate on the shape of the pelvic bone, however, is comparatively limited, explaining only a small percentage of shape variation in males and females. In accordance with previous hypotheses, the size of the os coxae tends to increase with decreasing temperature, although the significance of the association is reduced when population history is taken into account. In conclusion, the shape and size of the human os coxae reflect both neutral evolutionary processes and climatically-driven adaptive changes. Neutral processes have a substantial effect on pelvic variation, suggesting such factors will need to be taken into account in future studies of human and fossil hominin coxal variation.
现代人类群体之间以及已灭绝的古人类物种之间骨盆宽度的差异，常常根据体温调节适应性来解释，即较大的骨盆带有助于在寒冷环境中保持体温，而较窄的骨盆则有助于在热带气候中散热。然而，在没有首先考虑中性进化过程（即突变、遗传漂变和迁移）的影响的情况下，将变异模式解释为选择的证据存在一个理论问题。在这里，我们分析了来自五大洲、具有一系列气候条件的1494名现代人类个体（代表30个男性群体和23个女性群体）髋骨上27个地标点的三维构型。我们测试了气候对骨盆骨大小和形状的影响，同时明确考虑了群体历史（即地理介导的基因流动和遗传漂变）。我们发现，中性过程在男女髋骨形状变异中占很大比例。除了由于群体历史导致的中性模式外，温度是髋骨形状和大小变异的一个重要预测因素，至少在男性中是这样。然而，气候对骨盆骨形状的影响相对有限，仅解释了男性和女性形状变异的一小部分。与先前的假设一致，髋骨大小往往随着温度降低而增加，尽管在考虑群体历史时这种关联的显著性会降低。总之，人类髋骨的形状和大小既反映了中性进化过程，也反映了气候驱动的适应性变化。中性过程对骨盆变异有很大影响，这表明在未来关于人类和化石古人类髋骨变异的研究中需要考虑这些因素。
