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Showing posts with label Tibet. Show all posts
Showing posts with label Tibet. Show all posts

Saturday, August 17, 2019

A surprising twist to the Shirenzigou nomads story


Remember those potentially Afanasievo-derived and Tocharian-related Shirenzigou nomads from the Ning et al. paper? Well, in my opinion, they're probably neither. The genotypes and other data for these Iron Age individuals from the eastern Tian Shan are available here.

Below are a few successful and not so successful qpAdm mixture models for them. Note that I tried to use a wide range of relevant "right pops", but also retain a lot of markers, specifically to be able to discriminate between different types of steppe and steppe-derived sources of gene flow (refer to the full output). Admittedly, the Shirenzigou nomads can be modeled with Afanasievo-related ancestry, but...

CHN_Shirenzigou_IA
KAZ_Botai 0.161±0.023
KAZ_Wusun 0.490±0.023
NPL_Mebrak_2125BP 0.349±0.019

chisq 5.793
tail prob 0.926172
Full output

CHN_Shirenzigou_IA
KAZ_Botai 0.143±0.022
NPL_Mebrak_2125BP 0.295±0.019
Saka_Tian_Shan 0.562±0.024

chisq 6.796
tail prob 0.870794
Full output

CHN_Shirenzigou_IA
KAZ_Botai 0.185±0.023
NPL_Mebrak_2125BP 0.428±0.021
RUS_Sintashta_MLBA 0.270±0.026
TJK_Sarazm_En 0.117±0.027

chisq 11.351
tail prob 0.414345
Full output

CHN_Shirenzigou_IA
KAZ_Botai 0.032±0.027
KAZ_Zevakinskiy_LBA 0.567±0.025
NPL_Mebrak_2125BP 0.401±0.019

chisq 15.157
tail prob 0.232961
Full output

CHN_Shirenzigou_IA
NPL_Mebrak_2125BP 0.452±0.031
RUS_Afanasievo 0.435±0.025
RUS_Okunevo_BA 0.114±0.049

chisq 19.808
tail prob 0.0708003
Full output

CHN_Shirenzigou_IA
NPL_Mebrak_2125BP 0.409±0.031
RUS_Okunevo_BA 0.173±0.050
Yamnaya_RUS_Caucasus 0.418±0.026

chisq 20.453
tail prob 0.0589872
Full output

CHN_Shirenzigou_IA
NPL_Mebrak_2125BP 0.464±0.033
RUS_Okunevo_BA 0.104±0.053
Yamnaya_RUS_Samara 0.432±0.027

chisq 27.189
tail prob 0.0072566
Full output

Both the Wusun and Saka are generally accepted to have been the speakers of Indo-Iranian languages. So it's possible that the Shirenzigou nomads were Indo-Iranian speakers too, or at least derived from such peoples.

Surprisingly, NPL_Mebrak_2125BP was the key to obtaining the best statistical fits. This is a trio of samples, roughly contemporaneous with the Shirenzigou nomads, from a burial site high up in the Himalayas in what is now Nepal (see here).

To be honest, I'm not quite sure why the Himalayan ancients work so well in my models. Perhaps they're just a really good proxy for an Iron Age population from the northern edge of the Tibetan Plateau?

By the way, most of the Shirenzigou nomads made it into the latest Global25 datasheets (see here). They can be analyzed in a variety of ways described in this blog post: Getting the most out of the Global25. Below is a screen cap of me comparing the effectiveness of Afanasievo, Sintashta and Wusun samples as proxies for the steppe ancestry in the Shirenzigou nomads with an online tool freely available here. As expected, the algorithm picks Sintashta ahead of Afanasievo, and the Wusun ahead of both.


See also...

They mixed up Huns with Tocharians

Some myths die hard

The mystery of the Sintashta people