Ancient West Siberian mtDNA

Kristiina called my attention recently to this open access article on the ancient mtDNA of a district of South-Western Siberia known as Baraba.

V.I. Molodin et al., Human migrations in the southern region of the West Siberian Plain during the Bronze Age: Archaeological, palaeogenetic and anthropological data. Part of a wider book published by De Gruyter (2013). Open access → LINK

Fig. 1 - click to expand

Quite interestingly we see in the data that before 3000 BCE this part of Western Siberia (see locator map at the right) shows already signs of West-East admixture, much earlier than Central Asia did.

This fact is consistent with the apparently old admixture detected among the Khanty in autosomal DNA and also with the Epipaleolithic presence of East Asian mtDNA (C1) in NE Europe and the putative Siberian origins of the Uralic family of languages and Y-DNA haplogroup N in NE Europe.

Fig. 2 (left) | Chronological time scale of Bronze Age Cultures from the Baraba region
Fig. 3 (main) | Phylogenetic tree of 92 mtDNA samples obtained from the seven Bronze Age cultural groups from the Baraba region. Color coding of the groups as in Figure 2

The Ust-Tartas culture is part of the wider Combed Pottery culture, usually thought to be at the origins of Uralic peoples in NE Europe and Western Siberia, and shows an almost balanced apportion of Eastern lineages (C, Z, A, D) and Western ones (U5a, U4, U2e), suggesting that the process of admixture was by then already consolidated. 

However the Odinovo cultural phase shows a change in this trend, with a clear hegemony of Eastern lineages (notably D) and almost vanishing of Western ones. Trend that continues in its broadest terms in the Early Krotovo phase. 

Odinovo is part of the wider phenomenon known as Seima-Turbino, initiator of the Bronze Age in wide parts of Northern Asia and believed to be original of Altai. However the lineages do not correspond at all with the Altaian Bronze Age genetic pool, fully Western in affinity, excepted those from Mongolian Altai, which are all D. Hence the apparent demic replacement happening in this period must have been from the Mongolian part of Altai or some other region and not the core Altai area.

The oriental affinity of Early Krotovo is instead caused by a more diverse array of lineages (less D more CZ and A), which is interpreted materially as reflecting migrations from Northern Kazakhstan (Petrovo culture). However, as mentioned before the known mtDNA pool of Central Asia in that period is completely of Western Affinity, so we must in principle discard Kazakhstan as the origin of the probable demic flows.

Let me here mention that the authors insist on continuity through these three phases, however I see a very different picture in the same data, with Western lineages almost vanishing with Odinovo and Eastern ones clearly changing in frequency well beyond reasonable expectations on random fluctuations.

It is only in Late Krotovo when Western lineages reappear in significant numbers, probably reflecting, now yes, migrational flows from the South. This trend is clearly reinforced in the Andronovo, Baraba Late Bronze and transition to Iron Age phases, suggesting growing influence from Andronovo culture (early Indo-Iranians).