Migliano Andrea Bamberg, Vinicius Lucio, Lahr Marta Mirazón
Leverhulme Centre for Human Evolutionary Studies, University of Cambridge, The Henry Wellcome Building, Fitzwilliam Street, Cambridge CB2 1QH, United Kingdom.
Proc Natl Acad Sci U S A. 2007 Dec 18;104(51):20216-9. doi: 10.1073/pnas.0708024105. Epub 2007 Dec 11.
Explanations for the evolution of human pygmies continue to be a matter of controversy, recently fuelled by the disagreements surrounding the interpretation of the fossil hominin Homo floresiensis. Traditional hypotheses assume that the small body size of human pygmies is an adaptation to special challenges, such as thermoregulation, locomotion in dense forests, or endurance against starvation. Here, we present an analysis of stature, growth, and individual fitness for a large population of Aeta and a smaller one of Batak from the Philippines and compare it with data on other pygmy groups accumulated by anthropologists for a century. The results challenge traditional explanations of human pygmy body size. We argue that human pygmy populations and adaptations evolved independently as the result of a life history tradeoff between the fertility benefits of larger body size against the costs of late growth cessation, under circumstances of significant young and adult mortality. Human pygmies do not appear to have evolved through positive selection for small stature-this was a by-product of selection for early onset of reproduction.
对人类侏儒症进化的解释一直存在争议，最近围绕弗洛勒斯人化石的解释分歧更是火上浇油。传统假说认为，人类侏儒症患者身材矮小是对特殊挑战的一种适应，比如体温调节、在茂密森林中行动，或者抵御饥饿的耐力。在此，我们对菲律宾大量阿埃塔人和少量巴塔克人的身高、生长和个体健康状况进行了分析，并将其与人类学家一个世纪以来积累的其他侏儒群体的数据进行了比较。结果对人类侏儒症身材大小的传统解释提出了挑战。我们认为，在幼年和成年死亡率较高的情况下，由于身材较大带来的生育优势与生长停止较晚的成本之间存在生活史权衡，人类侏儒群体及其适应性是独立进化的。人类侏儒症似乎并非通过对矮小身材的正向选择进化而来——这是对早育选择的一个副产品。
