Population strata in the West Siberian plain (Baraba forest steppe)

Also from the Population Dynamics in Prehistory and Early History (2012) volume, this is an awesome ancient DNA study which dissects a succession of archaeological cultures stretching from the beginning of the metal ages to the beginning of the Iron Age in a small region of West Siberia. As the authors write:

Our work is devoted to the analysis of human migration processes that occurred during the Bronze Age (4th–early 1st millennium BC) in the forest steppe zone between the Ob and Irtysh rivers (about 800 km from west to east). This area, known as Baraba forest steppe, stretches over 200 km from the taiga zone in the north to the steppes in the south.

The careful examination of the sequence of cultures, combining ancient mtDNA and physical anthropology paints a very compelling picture of the changes that occurred in the span of a few millennia in the Baraba forest steppe. The authors give the map on the left, with the caption: "Fig. 5 | Location of ancient human groups with a high frequency of mtDNA haplogroups U5, U4 and U2e lineages. The area of Northern Eurasian anthropological formation is marked by yellow region on the map (References: 1 Bramanti et al., 2009; 2Malmstrom et al., 2009; 3 Krause et al., 2010; 4 this study)".


The northern Eurasian anthropological formation actually combines eastern and western Eurasian features and may correspond to the Proto-Uralic type. Researchers have clashed about the origins of this population element, with some considering it a third Eurasian race that evolved independently of Caucasoids and Mongoloids, others assigning it to a much diverged branch of one of the two major Eurasian races, and still others considering it the product of admixture between east and west.


All indications are that the type, unlike the Caucasoid-Mongoloid mixtures that took place in Central Asia in the last 2 millennia, is of more ancient vintage, and represents an anthropological element that was indeed of Caucasoid-Mongoloid origins, but in the rather remote past. The authors write with respect to the most ancient periods:

In contrast to the occupation of the southern region of West Siberia, modern humans arrived in the Ob-Irtysh interfluve relatively late, at the end of the Pleistocene, about 13–14 thousand years ago (Okladnikov, Molodin, 1983; Petrin, 1986). The absence of burials dating back to this period in the region does not allow us to conduct a biological investigation of this earliest population. The most ancient anthropological material available is from the Neolithic period (4th–5th millennium BC). 

And, what of the earliest available material?

The anthropological analysis of the material allowed us to detect a specific craniological type in the Baraba population, which was assigned to one of the anthropological formations discovered by V.V. Bunak in 1956 through the analysis of Neolithic materials from the northern forest zone of the East European Plain. Bunak called it the “northern Eurasian anthropological formation” (Bunak, 1956).

This anthropological type developed in a zone that is intermediate to the geographic areas occupied by the classic Caucasoids and the Mongoloids. The exists substantial anthropological evidence showing a wide geographic distribution of this anthropological formation: from the Trans-Urals forest and the Barabian province of Western Siberia in the east to Karelia and the Baltic in the west (Chikisheva, 2010).

The mtDNA evidence seems to support the anthropological assessment:

We have analyzed 18 mtDNA samples from the Ust-Tartas population to date (Fig. 3). The results obtained thus far allow us to draw several preliminary conclusions about the genetic background in the region in the beginning of the Bronze Age. By the Early Metal Period the mtDNA pool structure was already mixed and consisted of both Western and Eastern Eurasian haplogroups in nearly equal proportions. The eastern Eurasian mtDNA cluster was represented by Haplogroups A, C, Z, D, which are most typical of modern and perhaps ancient populations located in the east of the region studied. Haplogroups C and D were predominantly represented by widely distributed root haplotypes. A lineage of Haplogroup A that was detected in two Ust-Tartas samples represents a subcluster that is apparently characteristic of West Siberia and the Volga-Ural Region. The observed presence of Haplogroup Z lineages with a high frequency in the Ust-Tartas group was unexpected, since these lineages are nearly absent in the gene pool of modern indigenous West Siberian populations.

It is worth noting that the Western Eurasian mtDNA haplogroups in the Ust-Tartas series were represented only by Haplogroup U lineages, and specifically by the three subgroups – U2e, U4, U5a1. These results are in agreement with previous data indicating that Haplogroup U lineages (particularly Subgroups U5 and U4) predominated in Eastern, Central and Northern European hunter-gatherer groups from 14000 to 4000 years ago (Bramanti et al., 2009; Malmstrom et al., 2009), and possibly in earlier periods (Krause et al., 2010). The geographic area within which this genetic feature is observed appears to be broad (Fig. 5). Apparently, Baraba was near the eastern periphery of this area.

We now have evidence of the zone of U dominance extending from Iberia in the west and all the way to Lake Baikal in the east. But, this zone is not homogeneous: its western, European, end appears to have lacked the East Eurasian lineages, while starting from Ukraine and to the East the U types were supplemented by the Mongoloid lineages.

But, there was structure within the U zone itself: according to Lillie et al. (same volume) in Ukraine during the 6th millennium BC, the West Eurasian types were represented by U1 and U3, a different mix than in the Baraba forest steppe, and haplogroup T was also present, while of the Mongoloid haplogroups only C was present.

As we head into the Bronze Age, the population of the region displayed signs of continuity:

The genetic analysis of the Odinovo and Krotovo groups (10 and 6 samples, respectively) (Fig. 3) did not reveal any differences between them and the previous Ust-Tartas group, such as the presence of new mtDNA haplogroups. The mtDNA pool structure was still mixed. The East Eurasian haplogroups were represented by the D, C, Z (in both the Odinovo and Krotovo groups) and A (in the Krotovo group) haplogroups. The East Eurasian lineages identified were phylogenetically close (lineages of haplogroups A, C, Z) or even identical (D haplogroup, 16223–16362 lineages) to the samples from the Ust-Tartas group. The West Eurasian part of the samples were represented by the U5a1 (Odinovo group) and U2e (Krotovo group) haplogroup lineages.  

Although only a small series of samples have been investigated thus far, the data obtained reveal continuity between the Odinovo and Krotovo populations and the earlier Ust-Tartas group. These findings are consistent with the autochthonous development of the Baraba populations during the Early and the beginning of the Middle Bronze Age, as well as with the anthropological evidence.  

It is during the Middle and Late Bronze ages that we begin to say the first intrusive lineage into the native population mix:

The anthropological analysis of the West Siberian Andronovo population shows at least four craniological types. Three types are related to the Palaeocaucasian race and are represented by proto-European anthropological type variants. The fourth, Mongoloid, component is autochthonous. The most intensive interactions between the Andronovo migrants and the indigenous populations apparently occurred in the Baraba forest steppe and the right bank of the upper Ob River (Chikisheva and Pozdnyakov, 2003).  

To investigate the putative impact of Andronovo migrants on the mtDNA pool structure of the indigenous populations in Baraba, mtDNA samples from the Late Krotovo (n=20) and Andronovo (n=20) groups in this region were analyzed (Fig. 3) and compared to recently published data (n=10) (Keyser et al., 2009) and our own unpublished data (n=6) on mtDNA lineages from West Siberian Andronovo populations located outside the Baraba forest steppe.  

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.  

We also detected another remarkable feature in the mtDNA pool of the Andronovo group from Baraba. Most mtDNA samples belonged to haplogroups, such as the East Eurasian A and C haplogroups, that are typical of preceding Baraba indigenous populations. Still, these haplogroups were not found in the other West Siberian Andronovo groups. Apparently, the Andronovo group from Baraba assimilated the aboriginal Krotovo population, from which it obtained these East-Eurasian mtDNA haplogroups. Obviously, there was reciprocal genetic contact between the migrant and indigenous groups in the region. 

...

A small but informative series of mtDNA samples from the Baraba Late Bronze Age culture population (n=5) was analyzed (Fig. 3), revealing the presence of MtDNA lineages (East Eurasian A and C lineages) that mark the genetic continuity with aboriginal Baraba groups. At the same time, the series includes the Haplogroup-T lineage, which we believe marks the Andronovo migration wave to West Siberia. Our data is therefore consistent with the putative origin of the West Siberian Late Bronze Culture population as the result of interaction between the Baraba indigenous genetic substrate and the newly arrived group.

It is now clear that the Andronovo groups moving into the area possessed mtDNA haplogroup T and assimilated the locals with their U+East Eurasian mix. It is of course interesting that haplogroup T is the only non-U lineage found in the aforementioned study of Mariupol-type cemeteries from Neolithic Ukraine.

The earliest occurrence of haplogroup T is in the Pre-Pottery Neolithic B of the Near East (Tell Hallula), and this haplogroup appears all over the place in Neolithic Europe. While a recent article has suggested a pre-Neolithic dispersal of T subclades into Europe, on the basis of modern populations, this hypothesis is difficult to reconcile with the ancient DNA data.


Pending new discoveries, it appears likely that mtDNA haplogroup T represents a Neolithic entrant into the boreal zone of U dominance. This has, of course, substantial implications in the context of J.P. Mallory's concept of fault lines, as it demonstrates that the steppe populations did not evolve in isolation, but the dominant lineage in the Andronovo groups was a late entrant into the indigenous U-zone of the eastern European plain.

But, the story doesn't end here:

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. The impact of the northern human groups was probably less evident in the south of the Baraba forest steppe, at least at the mtDNA level. 

The drastic appearance of a purely Caucasoid population at the Iron Age from a southern, east-Caspian origin perhaps corresponds to the arrival of the first steppe Iranians. The vector of proposed migration is reasonable, if we consider both the likely Indo-Iranian homeland east of the Caspian, as well as the literary evidence for Scythian mobility during this period.

All in all, this is commendable research which allows us to intuit a sequence of events:

• An early mixture zone between Caucasoids and Mongoloids
• The Bronze Age arrival of mtDNA-T bearing Andronovo groups, the first pastoralists entering the zone of U+East Eurasian boreal hunter-gatherers; these Caucasoid peoples admixed with the natives of the mixture zone.
• The early Iron Age arrival of a full-blown set of Caucasoid mtDNA lineages from the south paving the way for the Iranian Scytho-Sarmatian period

Human migrations in the southern region of the West Siberian Plain during the Bronze Age: Archaeological, palaeogenetic and anthropological data


Molodin, Vyacheslav I. et al.


In this paper we present archaeological and anthropological data on human migrations in the Western Siberian foreststeppe region during the Bronze Age (4th–beginning of 1st millennium BC). These data, accumulated over forty years of intensive research in the region, are compared to new results showing the diversity of mitochondrial DNA (mtDNA) lineages in this region during that period (92 mtDNA samples from seven ancient human groups). Preliminary analyses have demonstrated the usefulness of ancient DNA in tracing and unravelling patterns of past human migrations.  


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Prehistoric populations of Ukraine: Migration at the later Mesolithic to Neolithic transition


Lillie, Malcolm C. et al.


This paper focuses on the identification of population movements during the Mesolithic and Neolithic periods in the Dnieper Basin region of Ukraine. We assess the evidence for migration from the perspective of individual life histories using a combination of palaeoanthropology/pathology, radiocarbon dating, stable isotopic studies of diet, and mtDNA. 


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