Anthropology.net

Inspired by the Dodecad Ancestry Project by Dienekes Pontikos and Eurogenes Ancestry Project by David Wesolowski, Zack Ajmal (with the help of Razib Khan) has started the Harappa Ancestry Project. Zack explains the motivation behind this project,

“It is a project to analyze (autosomal) genetic data of participants of South Asian origin for the purpose of providing detailed ancestry information. So the focus of the project is on South Asians: Indians, Pakistanis, Bangladeshis and Sri Lankans.

The project will collect 23andme raw genetic data from participants to better understand the ancestry relationships of different South Asian ethnicities.

I have named it after Harappa, an archaeological site of the Indus Valley Civilization in Punjab, Pakistan.”

There was a nice deal running on 23andme about a month ago for their ancestry & health kit that worked out to be $160 for 1 year. I hopped on board, got my kit, spat in the tube and sent it off. It is currently being analyzed. My ancestry is one of the populations Zack is looking for — so I’ll be sending my data to him. I can’t wait.

If you have had a 23andme genetic testing, you should consider participating in this project. It looks to be very interesting.

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)

Razib shares with us an overview of a new PLoS One paper which investigated the selection of an allele of alcohol dehydrogenase found in high frequency in some East Asian peoples. I gotta hand it to him for the snarky title of his post. Alcohol dehydrogenase is an enzyme that functions to break down alcohols which could otherwise be toxic. There are many classes of alcohol dehydrogenases. The specific allele in this study, ADH1b*47His, is associated with a decrease in the risk of alcoholism. How? These class of alcohol dehydrogenase (ADH) alleles expedite the metabolism of alcohols. Alleles that metabolize alcohols slower, such as the ADH2 and ADH3 variants, are associated with alcoholics.

The observation that ADH1b*47His is found in high frequencies in some East Asian populations have got Hui Li and coauthors curious to figure out if there has been some sort of selection to confer this decrease of alcoholism allele to be present in many peoples. They recently published their study in the free and open access journal, PLoS One. The research behind this paper, “Ethnic Related Selection for an ADH Class I Variant within East Asia,” involved looking at 30 different SNPs in the ADH gene of 24 different populations. It was observed that the unique ADH1b alleles correlated directly with ethnic groups, which I think is completely fascinating from an anthropological perspective.

In their population screen, it was observed that the ADH1b*47His allele is found highest in Korean-Japanese, Han Chinese, Hmong-Mien, Daic, and Austronesian people. Further, investigation of the ADH gene revealed that ADH1b*47His is actually a SNP that falls smack dab in the regulatory region of ADH. Regulatory regions are portions of a gene where promoters, inhibitors, and other transcription factors bind preferentially. Any alteration of these regions of genes ultimately effects how much product is made.

As Razib highlighted, the authors think that the real focus of selection may be the regulatory region. Well, no duh, the derived promoter allele probably increased expression levels of the enzyme and with more enzyme available, that ultimately helped people process alcohol more efficiently and faster. Clearly there’s a selective advantage to having more enzymes available to oxidize toxic agents. But the authors are a bit conservative in saying that detoxifying alcohol is primary reason why ADH1b*47His is present in high frequency in East Asian people. In fact, they suggest that ADH1 alleles have something to do with cancer, infectious diseases, etc. Makes sense, I mean these enzymes are detoxifying agents.

I know this post was heavy on population genetics, biochemistry and some physiology. I have to review that to some extent to give a background on ADH. I do want to point out again that this study yet again shows us that there are genetic differences between ethnic groups. Be it in ADH, or any other ancestry inherited marker, ethnic populations do exhibit some clearly definable genetic differences.

Li, H., Gu, S., Cai, X., Speed, W.C., Pakstis, A.J., Golub, E.I., Kidd, J.R., Kidd, K.K., Harpending, H. (2008). Ethnic Related Selection for an ADH Class I Variant within East Asia. PLoS ONE, 3(4), e1881. DOI: 10.1371/journal.pone.0001881