Ghirotto Silvia, Penso-Dolfin Luca, Barbujani Guido
Dipartimento di Biologia ed Evoluzione, Università di Ferrara, Ferrara, Italy.
Hum Biol. 2011 Aug;83(4):477-89. doi: 10.3378/027.083.0403.
There is general agreement among scientists about a recent (less than 200,000 yrs ago) African origin of anatomically modern humans, whereas there is still uncertainty about whether, and to what extent, they admixed with archaic populations, which thus may have contributed to the modern populations' gene pools. Data on cranial morphology have been interpreted as suggesting that, before the main expansion from Africa through the Near East, anatomically modern humans may also have taken a Southern route from the Horn of Africa through the Arabian peninsula to India, Melanesia and Australia, about 100,000 yrs ago. This view was recently supported by archaeological findings demonstrating human presence in Eastern Arabia >90,000 yrs ago. In this study we analyzed genetic variation at 111,197 nuclear SNPs in nine populations (Kurumba, Chenchu, Kamsali, Madiga, Mala, Irula, Dalit, Chinese, Japanese), chosen because their genealogical relationships are expected to differ under the alternative models of expansion (single vs. multiple dispersals). We calculated correlations between genomic distances, and geographic distances estimated under the alternative assumptions of a single dispersal, or multiple dispersals, and found a significantly stronger association for the multiple dispersal model. If confirmed, this result would cast doubts on the possibility that some non-African populations (i.e., those whose ancestors expanded through the Southern route) may have had any contacts with Neandertals.
科学家们普遍认同解剖学意义上的现代人类起源于近期（不到20万年前）的非洲，然而，对于他们是否以及在何种程度上与古代人群发生了基因混合，进而可能对现代人群的基因库有所贡献，仍然存在不确定性。有关颅骨形态的数据被解读为表明，在从非洲经近东地区的主要扩张之前，解剖学意义上的现代人类大约在10万年前也可能从非洲之角经阿拉伯半岛走了一条南线，到达印度、美拉尼西亚和澳大利亚。这一观点最近得到了考古发现的支持，这些发现表明在9万多年前阿拉伯东部就有人类存在。在这项研究中，我们分析了九个群体（库伦巴人、陈楚人、坎萨利人、马迪加人、马拉人、伊鲁拉人、达利特人、中国人、日本人）中111,197个核单核苷酸多态性位点的遗传变异，选择这些群体是因为在不同的扩张模型（单次扩散与多次扩散）下，他们的谱系关系预计会有所不同。我们计算了基因组距离与在单次扩散或多次扩散的不同假设下估计的地理距离之间的相关性，发现多次扩散模型的关联显著更强。如果这一结果得到证实，那么一些非非洲人群（即那些祖先通过南线扩张的人群）可能与尼安德特人有过任何接触的可能性就会受到质疑。
