Data from: Testing support for the northern and southern dispersal routes out of Africa: an analysis of Levantine and southern Arabian populations

Objectives: The Northern Dispersal Route (NDR) and Southern Dispersal Route (SDR) are hypothesized to have been used by modern humans in the dispersal out of Africa. The NDR follows the Nile into Northeast Africa and crosses the Red Sea into the Levant. The SDR emerges from the Horn of Africa and crosses the Bab el-Mandeb into southern Arabia. In this study, we analyze genetic data from populations living along the NDR and SDR to test support for each dispersal route.
Materials and methods: We genotyped 90 Yemeni samples on the Affymetrix Human Origins array. We analyzed these data with published data from Levantine and other southern Arabian populations as well as 157 comparative populations for a total sample size of >550,000 genetic variants from >2,000 individuals in >160 populations. We calculated outgroup f3 statistics to test how Levantine and southern Arabian populations relate to African populations living along the NDR and SDR and to other non-African populations.
Results: We find that Levantine and southern Arabian populations bear similar genetic relationships to both African and non-African populations, thus providing no support for the use of one dispersal route over the other.
Discussion: Our results are consistent with a history of gene flow between the Levant and southern Arabia. Consideration of genetic, archaeological, and paleoclimate data provide a slight edge for the SDR but, ultimately, more data are needed to definitively identify which dispersal route out of Africa was used.

研究目标：学界假说现代人类在走出非洲的迁徙扩散过程中曾采用北部扩散路线（Northern Dispersal Route, NDR）与南部扩散路线（Southern Dispersal Route, SDR）。其中北部扩散路线沿尼罗河进入东北非，随后跨红海抵达黎凡特（Levant）；南部扩散路线从非洲之角（Horn of Africa）出发，经曼德海峡（Bab el-Mandeb）进入阿拉伯南部地区。本研究针对沿两条扩散路线居住的人群的遗传数据展开分析，以验证两条扩散路线假说的合理性。
材料与方法：我们使用Affymetrix人类起源基因分型芯片（Affymetrix Human Origins array）对90份也门样本进行基因分型。将该数据与已发表的黎凡特地区、其他阿拉伯南部人群以及157个对照人群的数据进行整合分析，最终获得覆盖超过160个人群、2000余名个体的55万余个遗传变异位点的数据集。我们计算了外类群f3统计量（outgroup f3 statistics），以分析黎凡特地区与阿拉伯南部人群同沿两条扩散路线居住的非洲人群以及其他非非洲人群之间的遗传亲缘关系。
研究结果：研究结果显示，黎凡特地区与阿拉伯南部人群同非洲人群及非非洲人群均呈现相似的遗传亲缘关系，因此无法为其中某一条扩散路线的使用提供支持。
讨论：本研究结果与黎凡特地区与阿拉伯南部地区间存在基因交流的历史背景相符。综合遗传、考古及古气候数据来看，南部扩散路线略微占据优势，但最终仍需更多数据才能明确判定现代人类究竟采用了哪一条走出非洲的扩散路线。