Bronze and Iron Age population movements underlie Xinjiang population history:

The Xinjiang region in northwest China is a historically important geographical passage between East and West Eurasia. By sequencing 201 ancient genomes from 39 archaeological sites, we clarify the complex demographic history of this region. Bronze Age Xinjiang populations are characterized by four major ancestries related to Early Bronze Age cultures from the central and eastern Steppe, Central Asian, and Tarim Basin regions. Admixtures between Middle and Late Bronze Age Steppe cultures continued during the Late Bronze and Iron Ages, along with an inflow of East and Central Asian ancestry. Historical era populations show similar admixed and diverse ancestries as those of present-day Xinjiang populations. These results document the influence that East and West Eurasian populations have had over time in the different regions of Xinjiang.

This is a hard paper to read. The terminology could be clearer, and the narrative crisper. Perhaps this is just due to the need to compress into the length science wanted, I don’t know. But I find it hard to read, I doubt others will find it easier.

Here’s the main figure:

Here are my general summaries

1 – ~5,000 years ago the indigenous people of “Xinjiang” (northern half = Dzungaria, southern half = Uighurstan) were mostly distantly related to “Ancient North Eurasians” (the Tarim Basin mummies)

2 – Around this time early Indo-Europeans, the Afanasievo culture, begin to migrate south of the Altai pasturelands to the north. The Afanasievo are basically genetically 100% Yamnaya initially; their culture was really just an eastward migration of Yamnaya. They immediately start mixing with the indigenous ANE-related population, and also to some extent with small numbers of people from Northeast Asia.

3 – After 2000 BC two new entrants arrive on the scene. First, Indo-Iranians, second-wave Indo-Europeans who are different from the Afanesievo in having “Anatolian farmer” ancestry due to their provenance in the borderlands of Poland, Belarus and Ukraine. The Indo-Iranians, part of the Andronovo horizon, assimilate with the local populations, and almost certainly are responsible for some of the Iranian languages prominent in early historical records in the southwestern part of the Tarim Basin (e.g., Khotanese). Ad this time there is also a clear influx of Central Asian/Turanian ancestry related to the BMAC culture. These are basically pre-Indo-European Iranians, and you can think of them as strongly skewed to Zagrosian ancestry, along with some ANE/WSHG admixture, and minimal but nontrivial Anatolian farmer (the ancestors of the Indus Periphery population are zeroed out for Anatolian farmer).

If you look at admixture analyses of modern Uyghurs you see some Persian-related ancestry. This may in fact be Iranians from the medieval period, but perhaps more likely they’re due to the mixture between Andronovo and BMAC ancestry, which would perfectly mimic Persian ancestry.

At least period you also start seeing more East Asian ancestry with a southern affinity.

4 – By the historical period, you have the migration of populations from Central Asia, Siberia, and East Asia. Some of these you recognize. The Sakas and the Old Uyghurs for example. Others, you may not.

Looking at the admixture, one of the historical era samples is clearly Northwest Indian in ancestry. There is some evidence of Indian ancestry as early as the Bronze Age as well. This is a small component, but it is clearly not trivial. This particular result puts Kumarajiva in perspective.

The major finding of this paper seems to be that Xinjiang has not seen population replacement, but assimilation. The indigenous Tarim Basin ANE-derived population still make a substantial contribution to modern Uyghurs, as do the Afanasievo early Indo-Europeans, later Indo-Iranians, Xiongnu, Han Chinese and Central Asians.

Finally, it does look like the admixture between Afanasievo and ANE-derived indigenous populations dates to between 2500 and 3000 BC. Judging from the distinctiveness of Tocharian languages the authors claim that this means that it seems likely Tocharian is an Afanesievo language (and if that is true, then the original Yamnaya spoke something similar to Tocharian).

Native American gene flow into Polynesia predating Easter Island settlement:

The possibility of voyaging contact between prehistoric Polynesian and Native American populations has long intrigued researchers. Proponents have pointed to the existence of New World crops, such as the sweet potato and bottle gourd, in the Polynesian archaeological record, but nowhere else outside the pre-Columbian Americas…while critics have argued that these botanical dispersals need not have been human mediated…The Norwegian explorer Thor Heyerdahl controversially suggested that prehistoric South American populations had an important role in the settlement of east Polynesia and particularly of Easter Island (Rapa Nui)2. Several limited molecular genetic studies have reached opposing conclusions, and the possibility continues to be as hotly contested today as it was when first suggested…Here we analyse genome-wide variation in individuals from islands across Polynesia for signs of Native American admixture, analysing…individuals from 17 island populations and 15 Pacific coast Native American groups. We find conclusive evidence for prehistoric contact of Polynesian individuals with Native American individuals (around AD 1200) contemporaneous with the settlement of remote Oceania…Our analyses suggest strongly that a single contact event occurred in eastern Polynesia, before the settlement of Rapa Nui, between Polynesian individuals and a Native American group most closely related to the indigenous inhabitants of present-day Colombia.

I already recorded a podcast on The Insight with the first author that should post tonight. So I’m not going to put a long post, just subscribe to The Insight and listen to what the first author has to say.

The major finding using high density SNP chips and local ancestry deconvolution seems to be that a group of people from mainland South America, probably coastal Columbia, was admixed into the population of the Marquesas. It is from the Marquesas that this genetic ancestry propagated across the eastern fringe of Oceania, including Easter Island.

Update: The podcast has been pushed live. It should propagate in the next hour or so.