Paleoanthropology, Senckenberg Center for Human Evolution and Paleoenvironment, Eberhard Karls University of Tübingen, D-72070 Tübingen, Germany;
Department of Life Sciences and Biotechnology, University of Ferrara, I-44121 Ferrara, Italy; and.
Proc Natl Acad Sci U S A. 2014 May 20;111(20):7248-53. doi: 10.1073/pnas.1323666111. Epub 2014 Apr 21.
Despite broad consensus on Africa as the main place of origin for anatomically modern humans, their dispersal pattern out of the continent continues to be intensely debated. In extant human populations, the observation of decreasing genetic and phenotypic diversity at increasing distances from sub-Saharan Africa has been interpreted as evidence for a single dispersal, accompanied by a series of founder effects. In such a scenario, modern human genetic and phenotypic variation was primarily generated through successive population bottlenecks and drift during a rapid worldwide expansion out of Africa in the Late Pleistocene. However, recent genetic studies, as well as accumulating archaeological and paleoanthropological evidence, challenge this parsimonious model. They suggest instead a "southern route" dispersal into Asia as early as the late Middle Pleistocene, followed by a separate dispersal into northern Eurasia. Here we test these competing out-of-Africa scenarios by modeling hypothetical geographical migration routes and assessing their correlation with neutral population differentiation, as measured by genetic polymorphisms and cranial shape variables of modern human populations from Africa and Asia. We show that both lines of evidence support a multiple-dispersals model in which Australo-Melanesian populations are relatively isolated descendants of an early dispersal, whereas other Asian populations are descended from, or highly admixed with, members of a subsequent migration event.
尽管人们普遍认为非洲是现代人类的主要起源地，但他们离开非洲的扩散模式仍在激烈争论中。在现存的人类群体中，观察到的遗传和表型多样性随着距离撒哈拉以南非洲的增加而减少，这被解释为支持单一扩散的证据，同时伴随着一系列创始效应。在这种情况下，现代人类的遗传和表型变异主要是通过晚更新世时期快速的全球扩张过程中的连续人口瓶颈和漂移产生的。然而，最近的遗传研究以及不断积累的考古学和古人类学证据对这种简约模型提出了挑战。它们反而提出了一个“南方路线”，即在中更新世晚期就已经进入亚洲，然后再分别进入北亚。在这里，我们通过模拟假设的地理迁移路线，并评估其与中性种群分化的相关性，来检验这些替代性的走出非洲情景，这种相关性是通过非洲和亚洲现代人类群体的遗传多态性和颅骨形状变量来衡量的。我们表明，这两种证据都支持一种多扩散模型，即澳大拉西亚-美拉尼西亚人群是早期扩散的相对孤立的后裔，而其他亚洲人群则是后来迁徙事件的后裔，或者与其中的成员高度混合。
