Department of Life Sciences and Biotechnology, University of Ferrara, 44121 Ferrara, Italy.
Genes (Basel). 2020 Dec 16;11(12):1510. doi: 10.3390/genes11121510.
There is a wide consensus in considering Africa as the birthplace of anatomically modern humans (AMH), but the dispersal pattern and the main routes followed by our ancestors to colonize the world are still matters of debate. It is still an open question whether AMH left Africa through a single process, dispersing almost simultaneously over Asia and Europe, or in two main waves, first through the Arab Peninsula into southern Asia and Australo-Melanesia, and later through a northern route crossing the Levant. The development of new methodologies for inferring population history and the availability of worldwide high-coverage whole-genome sequences did not resolve this debate. In this work, we test the two main out-of-Africa hypotheses through an Approximate Bayesian Computation approach, based on the Random-Forest algorithm. We evaluated the ability of the method to discriminate between the alternative models of AMH out-of-Africa, using simulated data. Once assessed that the models are distinguishable, we compared simulated data with real genomic variation, from modern and archaic populations. This analysis showed that a model of multiple dispersals is four-fold as likely as the alternative single-dispersal model. According to our estimates, the two dispersal processes may be placed, respectively, around 74,000 and around 46,000 years ago.
人们普遍认为非洲是解剖学上的现代人类（AMH）的发源地，但人类祖先的扩散模式和主要迁徙路线仍存在争议。目前仍不清楚 AMH 是否是通过单一过程离开非洲的，即几乎同时扩散到亚洲和欧洲，还是通过两个主要波次扩散的，首先是通过阿拉伯半岛进入南亚和澳大拉西亚-美拉尼西亚，然后是通过穿过黎凡特的北部路线。用于推断种群历史的新方法的发展和全球范围内高覆盖率全基因组序列的可用性并没有解决这场争论。在这项工作中，我们通过基于随机森林算法的近似贝叶斯计算方法来测试两个主要的走出非洲假说。我们使用模拟数据评估了该方法区分 AMH 走出非洲替代模型的能力。一旦评估出模型是可区分的，我们将模拟数据与现代和古代人群的真实基因组变异进行了比较。这项分析表明，多波次扩散模型的可能性是替代的单次扩散模型的四倍。根据我们的估计，这两个扩散过程可能分别发生在大约 74000 年前和大约 46000 年前。
