Ancient DNA from Small River Cemetery Number 5

Someone asked about the reference to Siberian admixture in the NYT article on Ordek's necropolis. According to the paper reporting the DNA results, the majority of individuals tested belonged to a branch of haplogroup C4 that shows some similarities to one found among "Evenks and Udegeys of southeastern Siberia". Other mtDNA lineages detected include H and K. All Y chromosomes tested belonged to haplogroup R1a1a.

The shared sequences of the Xiaohe C haplotype (S1) were distributed in southeastern Siberia. It implies that the east Eurasian component in the Xiaohe people originated from the Siberian populations, especially the southern or eastern Siberian populations.

The mtDNA haplogroup H is the most common mtDNA haplogroup in Europe, especially in northwestern Europe, and its frequency can be as high as 65% in Iberia. Frequencies gradually decrease from the northwest to the southeast of Europe. By contrast, the frequency of haplogroup H rises to only 20% in the Near East, and to less than10% in Central Asia, and is very low in East Asia [33,34]. All of the shared sequences of the Xiaohe H haplotype, however, were distributed in Western Europe. Haplogroup K is also common in Europe, particularly around the Alps and the British Isles. It is found with less frequency in North Africa, the Middle East, and South Asia [21,35-37]. Considering the presence of haplogroups H and K in the Xiaohe people and the geographical distribution of shared sequences, we conclude that the west Eurasian component observed in the Xiaohe people originated from western European, and maternal ancestry of the Xiaohe people might have close relationship with western European.

Regarding the Y chromosomal DNA analyses, the seven males identified all belonged to haplogroup R1a1a. It is most frequently found in Eastern Europe, South Asia and Siberia. In contrast, it is relatively uncommon in Middle Easterners and rare in East Asian [22-24]. It is thought to be a trace of the migration events of early Indo-European [38,39]. The presence of haplogroup R1a1a in the ancient Xiaohe people implies that the parental ancestry of the Xiaohe people originated from somewhere in Siberia or Europe, which is consistent with the origin of maternal ancestry.

[Chunxiang Li et al. Evidence that a West-East admixed population lived in the Tarim Basin as early as the early Bronze Age. BMC Biology 2010, 8:15doi:10.1186/1741-7007-8-15.]