This new study found West-East Eurasian admixture in Mongolian Altai before the Iron Age. This finding partly contradicts previous data by González-Ruiz 2012 that suggested a strict genetic divide until the Iron Age.
Clemence Hollard et al., Strong genetic admixture in the Altai at the Middle Bronze Age revealed by uniparental and ancestry informative markers. FSI Genetics 2014. Pay per view → LINK [doi:10.1016/j.fsigen.2014.05.012]
The new data comes from two kurgan burial sites in Westernmost Mongolia: Tsagaan Asga and Takhilgat Uzuur-5 (abbreviated as TA and TU respectively).
In both sites mtDNA lineages have dual origins, although in TU (close to the Russian and Khazakh border) there is some prevalence of Western matrilineages (3/5), while in TA (somewhat farther East) the opposite is true instead (3/7 Western matrilineages), suggesting some clinality.
On the other hand Y-DNA is totally dominated by Western lineages with a single exception (C), although these Western lineages (Q and R1a) are of Central Asian/Siberian type without exception. Of course, Q variants have been lingering in Central Asia, Siberia and some parts of East Asia almost certainly since Aurignacian, being part of the early genesis of Native Americans (see here for a more in-depth discussion and here for China's Neolithic Y-DNA, which includes some Q), while R1a-Z93 seems a more recent arrival, maybe Epipaleolithic or Neolithic (see here), but both seem to have their origins in or near Iran, judging on basal diversity.
There is no trace of European-specific inflows on the Y-DNA side, even if some of the mtDNA lineages may be thought as having this origin (H1, H7, U4).
The Eastern ancestry is all typical of NE Asia. I would pay particular attention to mtDNA D, which seems to have spread in the Taiga with the Seima-Turbino phenomenon, which inaugurated the Bronze Age in that area and is believed to originate in Altai.
So, as conclusions, we can say that:
- There was incipient East-West admixture in parts of Altai already in the Bronze Age, the main actor of this admixture were females.
- Patrilineal ancestry was essentially "Western" of the kind that must have been in Altai since the Neolithic or earlier (i.e. not European but Central Asian of West Asian affinities/origins)
- The cultural context is Kurgan, strongly suggesting Indoeuropean language (of the Tocharian branch probably).
- The Seima-Turbino link however suggests some sort of affinity with carriers of the mtDNA D lineage in the Taiga in that same period, lineage not found further West in Altai. These Siberian Bronze Age vector people were very likely of Tungusic ethnicity. Although early Turkic connections cannot be totally ruled out, in general Turkic peoples seem more associated to the steppe instead and the roots of their expansion were probably forged some centuries later, already in the Iron Age.
- Both in the expansion of Indoeuropean eastwards and later in that of Altaic languages and ethnic affiliation westwards, the Altai region seems to have played a key pivotal role. However modern Altaians, even if Turkic by language, retain almost integrally the same Y-DNA genetic signature as the Bronze Age peoples mentioned here, what underlines their capacity to cross ethno-linguistic lines once and again while keeping their patrilineal ancestry nearly unaffected. They are therefore a good example of how populations can change ethno-linguistic ascription without significant genetic flow in such a key factor as the patrilineages. Surely many other peoples did the same in many other geographies. Ancestry and language need not to be linked, even if they sometimes are.