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Both Razib and Dienekes have reviewed a paper on the population genetics of Central Asian peoples. To make sense of Central Asian ancestry has been challenging, to say the least. In particular, the problem is compounded by nomadic peoples without much written history nor uncovered archaeological record.

Ethnicities of Central Asia

What we do have are the linguistic, physical features, and now because of this paper some of the allelic traits of the different populations. Razib has pointed out some strange phrases from the paper that make me wonder about how much background on Central Asian cultures, migrations and phenotypes the authors really knew before publishing. There is really no confusion that more western Central Asian people look more western while more eastern Central Asian people look eastern, with some but little, shared traits.  But I don’t put total blame on them for not doing their research, it’s hard to make sense of the ancestry of Central Asia.

Razib has done a nice job explaining some of the previous cultures. Do check his post out. But a quick introduction for those who want to know, the steppes of Central Asia during the pre-Islamic periods, were predominated by sedentary Iranian peoples like the Sogdians, Chorasmians, Scythians, and Alans. Between the 5th-10th century, Turkic peoples moved from the east through the west. Turkic is a name given to a group of people who share a linguistic ancestry, Altaic. Some of these groups you may know are the Uyghur and Tatars. The Hun are possibly Turkic. Another major Altaic, but not Turkic, migration occurred with the Mongols during the 13th century.

There has been some confusion regarding the folklore and historical record compared to the phenotypic and linguistic differences on just how impactful the Turkic replacement been. The western historical record indicates that the invading Hun of the 5th centuries and Mongols later made a significant impact, wiping out large portions of ancient ethnic Iranian populations. This understanding is both true and false. There is evidence of entire cities being destroyed. At the same time, in texts like Ghenghis Khan and the Making of the Modern World, you read statements on how the Altaic invasions was much less of a violent horde and was demonized because of their comparative weakness in written language. In other words, the captors of the Mongolian Empire wrote their account of their overlords.

To this day, this has lead to “nationalistic” and ethnic conflicts and confusion, as evidenced by the June massacres of the Uzbeks by Kyrgyz groups regarding ancestry and heritage. The general consensus is the Tajik and Uzbeks were once a majority Indo-European-speaking population that were assimilated by migrating Turkic-speaking groups. The divergence from Middle Iranian to Turkic and New Persian was predominantly the result of an elite dominance process, as Razib points out.

So, just to which ancestry do Tajiks and Uzbeks, who share a Indo-Iranian language family and the Karakalpaks, Kazaks, and Turkmen, who share a Turkic language family belong to? With a 1,500 year shared regional history but linguistic separation, is it possible to flesh out if Turkic people invaded the West and replaced populations, or was there a back flow of Westerners who moved east?

Geographic-Linguistic-Genetic location of 26 Central Asian populations

The results from the paper out in The European Journal of Human Genetics, indicate that,

“The analysis of genetic variation reveals that Central Asian diversity is mainly shaped by linguistic affiliation, with Turkic-speaking populations forming a cluster more closely related to East-Asian populations and Indo-Iranian speakers forming a cluster closer to Western Eurasians. “

STRUCTURE plot on Central Asian Populations

Dieneke points out how the STRUCTURE plot (above) lets us see the that eastern Hazaras and Uyghurs have remained relatively separate from the more western peoples. Furthermore, supplemented by Razib’s comment,

“The eastern Turkic groups seem the least impacted by the Iranian substrate which was dominant before the arrival of Turks, while the Turcoman group sampled from western Uzbekistan seems to have been the most genetically “Iranized.”

…the correspondence analysis shows the Turkic groups exhibited a linear distribution toward East Asia, while the Iranian ones were placed where you’d expect them geographically.”

The data from this paper indicates that Turkic people did in fact move west, especially the men, since there’s high degree of  genetic homogeneity on the Y chromosomal lineage. They remained more genetic and linguistically unified and did not assimilate into Iranian genetics and languages. Additionally, contrary to popular belief, they did not absorb large populations of Iranians as their genetics and languages remained more separate than integrate.

A disclaimer, this is but one paper, with limitations on the number allelic markers that would make fine population differences more noticeable. But we can still see large trends regarding the ancestry of Central Asian people.

Martínez-Cruz B, Vitalis R, Ségurel L, Austerlitz F, Georges M, Théry S, Quintana-Murci L, Hegay T, Aldashev A, Nasyrova F, & Heyer E (2010). In the heartland of Eurasia: the multilocus genetic landscape of Central Asian populations. European journal of human genetics : EJHG PMID: 20823912

Related Articles

• Major study of Central Asian populations (Martinez-Cruz et al. 2010) (dienekes.blogspot.com)

Thanks to the very helpful readers who have sent me a copy of the latest from Pääbo and crew, “Neanderthals in central Asia and Siberia.” I’ve read it, and it is a pretty good paper with solid methods. This study is important because it compliments paleoanthropology with molecular biology to fill in discrepancies with using morphology to classify remains. As you all know, fossils don’t come out as clean and intact as your grandmother’s china. Almost always hominid fossils are fragmented and incomplete.

That being said, the hominid remains from the Teshik Tash cave in Uzbekistan and the Okladnikov cave in the Altai region of Siberia are so fragmented and hard to classify, that for a long time paleoanthropologists have just put them aside. Lead author Krause et al. decided to dust off these specimens and break off about a fifth of a gram of bone from each to sequence and compare. Specifically, they harvested samples from the femur of the Teshik Tash kid and from three Okladnikov long bones.

Fossils don’t hold much DNA. Upon death, the body begins degrading DNA immediately, and only under certain conditions is DNA preserved enough so that one can extract DNA from a fossil. And once DNA is extracted, it is a really tiny amount which is muddled in a lot of contaminated DNA. So, in order to exponentially increase the amount of starting DNA, a technique called PCR, or polymerase chain reaction, is used. To do so, each segment of DNA needs to be primed, so that the PCR polymerases can bind to them and being duplicating. The DNA from these bones were amplified with three different primer pairs, I guess to test out which primer pair worked best.

Once the PCR reaction was complete the authors next sorted out modern human amplified DNA from Neandertal amplified DNA. They did this because, as I mentioned, there’s a lot of contamination, especially from modern human mtDNA on fossil bone. This is most likely due to handling and excavating the bone. After figuring out the modern human amplified products, it was found that the Teshik Tash kid and a subadult from Okladnikov, both yielded about 2 clones each of 60 Neandertal specific base pairs.

Since paleoanthropologists have spent all their time debating on how to classify the Okladnikov fossils, there seems to not be reliable dates for them. Krause and team dated them, and noted that the subadult from Okladnikov, the one that had Neandertal specific base pairs, was old enough (37,000 years old) to be a Neandertal.

With this date and the two pairs of Neandertal clones, the team narrowed down their scopes. They specifically designed primers that worked on amplifying only the hypervariable region 1 (HVR1) of Neandertal mtDNA. Why the HVR1? For starters the HVR1 is longer section than the 60 or so base pairs they already have. And since the HVR1 is an area where base pairs repeat and are highly polymorphic, it is a more informative section. Having longer sequences to align, compare, and analyze is much more statistically significant than shorter ones.

The authors sent off the Teshik Tash and Okladnikov samples to a DNA lab in France, which exactly matched up to their results, and confirmed they were doing the right stuff. After all the statistics, 300 base pairs from both the Teshik Tash and Okladnikov were compared to the same section of HVR1 from seven other Neandertals. They only differ in about 6 bases from the other Neandertals… that’s about a 98% similarity. Not bad at all.

What this study does is it pushes the geographical range of Neandertals, by 2,000 kilometers to the east. We already had an inkling Neandertals may have made it out to what is now Uzbekistan… hell they’ve been found in Iran. But to see that one of the Okladnikov fossils has Neandertal mtDNA that matches to European Neandertal mtDNA, calls for a big whoa. Neandertals in Siberia, whoa.