Turks and Mongol era admixture in Eurasia

Mavi Boncuk |

Mongol era admixture in Eurasia

The rapid expansion led by Genghis Khan and the subsequent Mongol empire (1206-1368CE: 1) is one of the most dramatic events in human history. One population believed to be at least partly descended from these Mongols, based on historical, linguistic and oral tradition, and unusual patterns of Y-chromosome male descent, are the Hazara from Pakistan (2, 3). In our analysis, which uses only autosomal genetic data, we independently infer this population to show the clearest signal of admixture in the entire dataset, with an admixture event occurring 22 (19-24) generations in the past, or 1306CE (1250-1390CE), between a source similar to the Iranians (55% contribution), and a source most closely similar among our sampled groups to present-day Mongolians (45%), confirming that both the date and origin of admixture link precisely to the Mongol empire. In fact we find that the Hazara are just one of seven populations (four among the top 20 clearest signals), including the Uyghur (4) and the Mongola themselves, who show an admixture event between a local source and a source closely genetically related to the Mongola, dating within the Mongol Period (Figure 2D). These populations were all sampled from within the range of the Mongol expansion and show a progressive westward decrease in Mongol ancestry. We however note that the slightly earlier date in the Turkish of 1250AD (1166-1362) is not inconsistent with other known Turkic pre-Genghis movements from East Asia, such as the Oghuz Turks (1).

Interestingly, the Mongola themselves show evidence of a more complex admixture history involving admixture between multiple groups at around the same time, with the strongest admixture direction involving primarily Northeast Asian groups on the one side and southern Chinese groups on the other, dated to 1334CE (1194-1446CE). This most prominent event corresponds to expectations based on the history of the Mongol empire (1). A second direction implies admixture involving a third group containing ancestry components more closely related to European populations. Because the Mongols spread right across Asia, this mixture appears highly consistent with the incorporation of DNA from both China and West Eurasia, within their empire, into the Mongolian population during this time, highlighting the potential impact of this period on the genetic ancestry across Eurasia.

References

1. C. Atwood P., "Encyclopedia of Mongolia and the Mongol Empire", Facts on File, Inc, New York, USA, 2004
2. E. E. Bacon, "The Inquiry into the History of the Hazara Mongols of Afghanistan", Southwest. J. Anthr. 7, 230–247 (1951)
3. T. Zerjal et al., "The genetic legacy of the Mongols", Am. J. Hum. Genet. 72, 717–721 (2003)
4. S. Xu, L. Jin, "A genome-wide analysis of admixture in Uyghurs and a high-density admixture map for disease-gene discovery", Am. J. Hum. Genet. 83, 322–336 (2008)
5. N. Patterson et al., "Ancient Admixture in Human History", Genetics 192, 1065–1093 (2012)
6. P. R. Loh et al., "Inferring Admixture Histories of Human Populations Using Linkage Disequilibrium", Genetics 193, 1233–1254 (2013)
7. S. Xu et al, "Analysis of Genomic Admixture in Uyghur and Its Implication in Mapping Strategy", Am. J. Hum. Genet. 82, 883–894 (2008)