|Ukok Plateau landscape|
(CC by Kobsev)
The Iron Age Pazyryk culture of Ukok Plateau (Altai Mountains, Central Asia) are generally considered to be related to Scythians or other Indoeuropean peoples of Western affinity. However the affiliation of Pazyryk peoples remains controversial. A new Catalan study may help to shed some light to the matter:
Mercedes González Ruiz et al., Tracing the Origin of the East-West Population Admixture in the Altai Region (Central Asia). PLoS ONE, 2012. Open access ··> LINK [doi:10.1371/journal.pone.0048904]
A recent discovery of Iron Age burials (Pazyryk culture) in the Altai Mountains of Mongolia may shed light on the mode and tempo of the generation of the current genetic east-west population admixture in Central Asia. Studies on ancient mitochondrial DNA of this region suggest that the Altai Mountains played the role of a geographical barrier between West and East Eurasian lineages until the beginning of the Iron Age. After the 7th century BC, coinciding with Scythian expansion across the Eurasian steppes, a gradual influx of East Eurasian sequences in Western steppes is detected. However, the underlying events behind the genetic admixture in Altai during the Iron Age are still unresolved: 1) whether it was a result of migratory events (eastward firstly, westward secondly), or 2) whether it was a result of a local demographic expansion in a ‘contact zone’ between European and East Asian people. In the present work, we analyzed the mitochondrial DNA lineages in human remains from Bronze and Iron Age burials of Mongolian Altai. Here we present support to the hypothesis that the gene pool of Iron Age inhabitants of Mongolian Altai was similar to that of western Iron Age Altaians (Russia and Kazakhstan). Thus, this people not only shared the same culture (Pazyryk), but also shared the same genetic east-west population admixture. In turn, Pazyryks appear to have a similar gene pool that current Altaians. Our results further show that Iron Age Altaians displayed mitochondrial lineages already present around Altai region before the Iron Age. This would provide support for a demographic expansion of local people of Altai instead of westward or eastward migratory events, as the demographic event behind the high population genetic admixture and diversity in Central Asia.
Surely the most interesting finding of this study is that, unlike all other studies so far in the area, Bronze Age burials¹ from westernmost Mongolia carried 100% (3/3) Eastern Asian haplogroups (all D). Only one sample from the same wider region and period had ever before produced some Eastern lineages but as minority (9%, Southern Siberia, Turbat 2005), all others producing instead 100% Western haplogroups.
Instead Iron Age burials produced a much more mixed picture (n=16):
- Eastern haplogroups: 8 (50%)
- A: 1
- C: 2
- D: 4
- G2a: 1
- Western haplogroups: 8 (50%)
- HV6: 1
- J: 1
- K: 3
- U5a1: 2
- T1: 1
This process however does not just imply penetration of Western lineages in the Mongolian part of Altai but also, as can be inferred in other studies' data, an extension of Oriental ones to the Western parts of Central Asia. The contrast between a well defined East-West genetic divide in the Bronze period and almost total blur in the Iron one instead is dramatically captured by these maps:
The authors conclude:
The Pazyryk groups analysed so far appear to be genetically homogeneous and they did not present significant genetic differences to current Altaians. These results suggest that roots of the current genetic diversity and admixture of the Altai region in Central Asia could be traced back to the Iron Age.
¹ Text minimally edited long after original publication because the Bronze Age burials from the region do not belong to Pazyryk culture (which only spans part of the Iron Age), as I wrongly said first.