Manica Andrea, Amos William, Balloux François, Hanihara Tsunehiko
Department of Zoology, University of Cambridge, Downing Street, Cambridge CB2 3EJ, UK.
Nature. 2007 Jul 19;448(7151):346-8. doi: 10.1038/nature05951.
The origin and patterns of dispersal of anatomically modern humans are the focus of considerable debate. Global genetic analyses have argued for one single origin, placed somewhere in Africa. This scenario implies a rapid expansion, with a series of bottlenecks of small amplitude, which would have led to the observed smooth loss of genetic diversity with increasing distance from Africa. Analyses of cranial data, on the other hand, have given mixed results, and have been argued to support multiple origins of modern humans. Using a large data set of skull measurements and an analytical framework equivalent to that used for genetic data, we show that the loss in genetic diversity has been mirrored by a loss in phenotypic variability. We find evidence for an African origin, placed somewhere in the central/southern part of the continent, which harbours the highest intra-population diversity in phenotypic measurements. We failed to find evidence for a second origin, and we confirm these results on a large genetic data set. Distance from Africa accounts for an average 19-25% of heritable variation in craniometric measurements-a remarkably strong effect for phenotypic measurements known to be under selection.
解剖学意义上的现代人类的起源及扩散模式是诸多争论的焦点。全球基因分析支持单一起源说，认为起源于非洲的某个地方。这种情况意味着快速扩张，伴随着一系列小幅度的瓶颈效应，这将导致随着与非洲距离的增加，出现所观察到的基因多样性的平稳丧失。另一方面，对头骨数据的分析结果不一，有人认为这些结果支持现代人类的多起源说。通过使用一个大型头骨测量数据集以及一个与用于基因数据的分析框架等效的分析框架，我们表明基因多样性的丧失反映在表型变异性的丧失上。我们发现有证据表明起源于非洲大陆中南部的某个地方，这里在表型测量方面具有最高的群体内多样性。我们没有找到二次起源的证据，并且我们在一个大型基因数据集上证实了这些结果。与非洲的距离平均占颅骨测量中可遗传变异的19% - 25%——对于已知受选择影响的表型测量来说，这是一个非常显著的效应。
