Here's a new paper that describes the genetic shifts that took place on the Baraba Steppe of the West Siberian Plain from the Neolithic to the Iron Age. It's part of an e-book with the latest stable isotope and ancient DNA data from across Eurasia, available free of charge here.
The authors argue that ancient mtDNA and cranial results show at least four different populations making their mark on the Baraba Steppe. These apparently include the aboriginal Western Siberians (carrying mtDNA haplogroups A,C,D and Z), Mesolithic Northeast Europeans from just across the Urals (U2e, U4 and U5), Bronze Age Andronovo nomads from what is now Central Kazakhstan (T, U5 and C), and late Bronze Age/early Iron Age Barabans from Chicha, possibly originally from West Central Asia (showing a wide variety of West Eurasian mtDNA haplogroups).
The analysis of mtDNA samples from the Chicha-1 population revealed some interesting patterns. Crucial changes in the composition of mtDNA haplogroups in the gene pool were observed as compared to the earlier Baraba groups studied (Fig. 3). Dominance of Western Eurasian haplogroups and the near absence of East Eurasian were observed. Additionally, several new West Eurasian haplogroups appeared in the region, including Haplogroups U1a, U3, U5b, K, H, J and W.
The phylogeographic analysis suggests that the distribution and diversification centres of several of these mtDNA haplogroups and specific lineages are located on the west and south west of the Baraba forest steppe region, on the territory corresponding to modern-day Kazakhstan and Western Central Asia (Fig. 10). Apparently, the migration wave from the south strongly influenced the gene pool of the Baraba population in the transitional period from the Bronze to the Early Iron Age.
Subsequently, in the Scythian-Sarmatian period, a large cultural group, called the Sargat culture, developed in the region. Its representatives were widespread across the region, from the Ob River to the Urals. Their development represented one of the most significant cultural events in North Asia.
Unlike the authors, however, I don't see any evidence in the paper that points to a southern origin of the Chicha group. In other words, I don't think there's any reason to believe that this population migrated to the Baraba Steppe from West Central Asia across the deserts near the Aral Sea.
In my opinion a more plausible explanation is that this was another wave of settlers from the western steppe of present-day Southern Russia and Ukraine. I suspect they basically followed in the footsteps of the earlier Andronovo groups. Such a scenario would match archaeological evidence, and also various ancient DNA results from Neolithic sites in Ukraine, which have shown most of the mtDNA haplogroups found in the Chicha individuals, like H, U1 and U3 (see, for instance my previous blog entry covering another article from the same e-book).
Indeed, it's interesting that haplogroup T is singled out in this study as a potential maternal marker of the Andronovo nomads from the Baraba Steppe. That's because this haplogroup has already been found among multiple Neolithic remains from Ukraine, and is fairly common today among populations from between the Baltic and Black seas.
The genetic influence of migrants can be detected by the appearance of a new mtDNA haplogroup that was absent in the populations preceding the migration wave. This new mtDNA haplogroup, a West Eurasian T haplogroup, was detected in the Late Krotovo population. The T haplogroup appears simultaneously (with a 15 % frequency) in the Krotovo and Andronovo groups, but was completely absent in all preceding Baraba populations. We therefore consider the appearance of the Haplogroup T-lineage as the most likely genetic marker of the Andronovo migration wave to the region.
This assumption is confirmed by mtDNA studies of Andronovo groups from other West Siberian areas. Haplogroup T lineages were found, with a frequency of 25 %, in the samples (n=16) taken from two Andronovo groups from the Krasnoyarsk and upper Ob River areas.
Molodin et al., Human migrations in the southern region of the West Siberian Plain during the Bronze Age: Archaeologcal, palaeogeneic and anthropoloical data, Population Dynamics in Prehistory and Early History (2012), Publication Date: July 2012, ISBN: 978-3-11-026630-6, DOI: 10.1515/9783110266306.93
Ed. by Kaiser, Elke / Burger, Joachim / Schier, Wolfram, Population Dynamics in Prehistory and Early History (2012), Publication Date: July 2012, ISBN: 978-3-11-026630-6, DOI: 10.1515/9783110266306.93
Ancient mtDNA from the Dnieper-Donets cultural complex
Surprising aDNA results from Neolithic and Bronze Age Ukraine
Ancient Siberians carrying R1a1 had light eyes - take 2