The Genomic History of the Middle East

The Middle East is an important region to understand human evolution and migrations, but is underrepresented in genetic studies. We generated and analysed 137 high-coverage physically-phased genome sequences from eight Middle Eastern populations using linked-read sequencing. We found no genetic traces of early expansions out-of-Africa in present-day populations, but find Arabians have elevated Basal Eurasian ancestry that dilutes their Neanderthal ancestry. A divergence in population size within the region starts before the Neolithic, when Levantines expanded while Arabians maintained small populations that could have derived ancestry from local epipaleolithic hunter-gatherers. All populations suffered a bottleneck overlapping the archaeologically-documented 4.2 kiloyear aridification of the area, while regional migrations increased genetic structure, and may have contributed to the spread of the Semitic languages. We identify new variants that show evidence of selection, some dating from the onset of the desert climate in the region. Our results thus provide detailed insights into the genomic and selective histories of the Middle East.