A new paper came out today on ancient East Asian DNA. More precisely, this work focused on early and late Neolithic samples from China, especially the lower Yellow river basin (north-central China) and the Fujian in southeast China. A major result can be boiled down to the Admixturegraph to the right.
The first ancient DNA out of East Eurasia was that from Tianyuan cave near modern Beijing. As you can see that individual is basal to other ancient (and modern) East Asians. That is, it isn’t representative of the ancestors of modern East Asians. But, the Tianyuan individual was already closer to modern East Asians than West Eurasians. Since the Tianyuan individual is ~40,000 years old, that means the bifurcation between eastern and western Eurasian groups predates 40,000 years ago.
This is not a surprising result, as the bifurcations between various “eastern” Eurasian groups (e.g., the ancestors of the Andamanese and East Asians) date to close to 50,000 years ago. The separation from Western Eurasians had to have happened after ~55,000 years ago since that’s about when the common shared Neanderthal admixture occurred.
The graph also shows that some ancient West Eurasian ancestry did come into the ancestors of East Asians through Siberians. More precisely, the Paleo-Siberian populations (replaced more recently by Neo-Siberian groups) had some ancestry from Ancient North Eurasians, who themselves were ~70% West Eurasian in ancestry (the other ~30% being a deeply basal East Eurasian). These Paleo-Siberians contributed ancestry to many northern East Asian groups, and likely explain the affinity between these groups and the Mal’ta-related individuals.
Finally, most of the edges show the separations between northern and southern East Asians and differences between inland and coastal populations. Though there is a deep distinction between northern and southern groups, the paper makes it clear that there is gene flow between coastal groups. This may explain affinities between the Japanese and Koreans, and peoples in southern China.
In terms of broad dynamics, one pattern that is evident, and repeats what we see all across Eurasia, is that the more recent periods seem to have undergone some level of panmixia. Ancient samples from northern and southern China are well differentiated, with pairwise Fst of around 0.04. Modern individuals sampled from these regions are closer to 0.02. Part of this is due to a significant expansion of “northern” ancestry at the expense of “southern”. But there is also some flow northward of “southern” ancestry. Though not highlighted in this paper because they lacked the samples, the movement throughout the Chinese Empire over the last 2,000 years is surely mediating this. In instances of famine or war resulting in depopulation in a province, the Chinese central authorities routinely encouraged migration from overpopulated provinces (modern Sichuan was repopulated from Hunan after a series of wars during the Ming-Qing transition). After 800 AD the demographic center China was in the Yangzi river valley, and south.
Unsurprisingly, the authors find that the southern samples from Fujian seem most similar to Austronesians. Today no one from these regions is “pure” southern. Rather, they are a mix. The Austronesians migrated out early enough that they carry southern East Asian ancestry exclusively. This recapitulates a common phenomenon where the ancestral “homeland” of a given group changes over time, reducing the ability to infer origins (e.g., the percentage of “Middle Eastern” ancestry in Southern Europe was underestimated because Anatolian farmers were partially replaced in Anatolia by migrants from the east).
There are also details in the supplements which confirm earlier inferences. For example, the Tianyuan individual has affinities with the Goyet Aurginacian sample from Belgium which dates to 35,000 years ago. But other East Asians do not. This seems to imply that Tianyuan was much more closely connected to a population that had trans-Eurasian affinities (another possibility is ancient structure, but the bifurcation between eastern and western Eurasian populations was more than 15,000 years before the time of Goyet so I am skeptical). Additionally, they also detect possible gene flow into Mesolithic Europeans from a population with East Asian ancestry (one possibility here that doesn’t seem to be explored is shared Ancient North Eurasian ancestry into both groups).
What is the overall takeaway? I think this confirms the other early papers that East Asia exhibits more continuity with its past that Europe and South Asian, rather like West Asia. While Europeans and South Asians have substantial ancestry from profoundly intrusive groups during the Holocene, the Han Chinese are in many ways “sons of the soil.” They did to some extent marginalize and absorb many other peoples in the modern area of “China proper”, and are themselves as a compound of two ancestral streams, but at the end of the last Ice Age, more than 90% of their ancestors were living within the boundaries of China proper.
More generally, modern imperial polities are exactly what some of their critics accuse of them of being: panmixia machines. Pre-state people were more genetically differentiated across local spatial scales. This seems the case everywhere there are good transects.
Related: The Deep Origins Of East Eurasians.