Department of Genetics and Howard Hughes Medical Institute, Harvard Medical School, Boston, MA 02115.
Proc Natl Acad Sci U S A. 2014 Feb 18;111(7):2632-7. doi: 10.1073/pnas.1313787111. Epub 2014 Feb 3.
The history of southern Africa involved interactions between indigenous hunter-gatherers and a range of populations that moved into the region. Here we use genome-wide genetic data to show that there are at least two admixture events in the history of Khoisan populations (southern African hunter-gatherers and pastoralists who speak non-Bantu languages with click consonants). One involved populations related to Niger-Congo-speaking African populations, and the other introduced ancestry most closely related to west Eurasian (European or Middle Eastern) populations. We date this latter admixture event to ∼900-1,800 y ago and show that it had the largest demographic impact in Khoisan populations that speak Khoe-Kwadi languages. A similar signal of west Eurasian ancestry is present throughout eastern Africa. In particular, we also find evidence for two admixture events in the history of Kenyan, Tanzanian, and Ethiopian populations, the earlier of which involved populations related to west Eurasians and which we date to ∼2,700-3,300 y ago. We reconstruct the allele frequencies of the putative west Eurasian population in eastern Africa and show that this population is a good proxy for the west Eurasian ancestry in southern Africa. The most parsimonious explanation for these findings is that west Eurasian ancestry entered southern Africa indirectly through eastern Africa.
南部非洲的历史涉及到土著狩猎采集者与一系列移入该地区的人群之间的互动。在这里，我们使用全基因组遗传数据表明，在科伊桑人群（南部非洲的狩猎采集者和牧民，他们说带有咔嗒音的非班图语）的历史上至少发生了两次混合事件。一次涉及到与尼日尔-刚果语系非洲人群有关的人群，另一次引入的祖先与西亚（欧洲或中东）人群最为密切相关。我们将这后一次混合事件的时间定在大约 900-1800 年前，并表明它对说科伊语的科伊桑人群的人口产生了最大的影响。在整个东非，都存在着类似的西亚祖先信号。特别是，我们还在肯尼亚、坦桑尼亚和埃塞俄比亚人群的历史中发现了两个混合事件的证据，其中较早的一次涉及到与西亚人群有关的人群，我们将其时间定在大约 2700-3300 年前。我们重建了东非假定的西亚人群的等位基因频率，并表明该人群是南非西亚祖先的良好代表。对这些发现最合理的解释是，西亚祖先通过东非间接进入了南非。
