After recording the “India genetics” podcast for The Insight and reading Early China: A Social and Cultural History, I wonder what surprises we’re going to get from China from ancient DNA when it comes online. If there is one thing we are learning by looking closely at DNA, modern and ancient, it’s that at least for humans there are very few ‘primal’ populations from the “Out of Africa” event which haven’t been threaded together from pulse admixtures of continuous gene flow across the landscape.
Early China makes it clear that Erlitou culture which dates from ~1900 to 1500 BC was almost certainly the legendary Xia dynasty. This means that the ethnogenesis of the modern Han Chinese probably dates to the latest ~4,000 years ago. This is centuries before the Indo-Aryans were likely arriving in South Asia, and around the same time that Indo-European groups were pushing into peninsular Southern Europe.
The Y chromosome data does not indicate a Bronze Age ‘star phylogeny’ expansion in East Asia that I know of, so the dynamics were not entirely similar to Western Eurasia. But, it seems quite plausible that the Han themselves are not a chrysalis from the late Pleistocene.
A cursory examination of the SNP data makes it clear that there is a north-south cline whereby the peoples north of the Yangzi have more West Eurasian admixture than those to the south. In fact, if you look at the PCA and admixture plot you notice that the Japanese have no West Eurasian ancestry. The Yayoi ancestry dominant among the Japanese probably arrived from southern Korea ~2,500 years ago. And, positioned away from the Chinese “mainland” southern Korea was relatively shielded from Inner Asian migrations (I am aware of Korea’s association with Manchuria and the extent of those early kingdoms).
In Empires of the Silk Road, Christopher Beckwith argues strongly for the role of Indo-Europeans in the ethnogenesis of the early proto-Han, through the influence of the Rong, Di, and Qiang. The Qiang were probably proto-Tibetan, but the genetically attested presence of people with overwhelmingly West Eurasian ancestry in areas like Dzungaria during the Bronze Age is well known. Y chromosome R1a1a is found at levels of a few percents among the northern Han, and perhaps as high as ~10% among the Mongolians (though R1b is found among many Uygurs, which is rare for Central Asia).
Beckwith points to the spread of chariot technology from Inner Asia ~1200 BC as strong evidence that Indo-Europeans were somehow involved with the rise of the Shang or Zhou, and so ties them into the emergence of Sinic civilization. Though it is clear that early Chinese chariots were originally derived from Inner Asian exemplars, as Egyptian chariots were, I think it is not unreasonable to suppose this was a case of genuine cultural diffusion and emulation of a useful weapon of war. Consider how quick native peoples in the New World adopted firearms and horses.
Within the next few years, we will have ancient DNA from a wide transect of Chinese history. Unlike some peoples the Chinese are highly historical people, so the genetics will not be stepping into the breach. We even have census records going back 2,000 years, and attempts of scholars to trace migrations based on the changing distribution of the taxable households (though note that some variation in the census count is due to tax dodging during times of political weakness).
I’ll hazard a prediction that most of the West Eurasian admixture into the North Chinese will be seen to be a function of the period after the fall of the Han dynasty and before the Sui-Tang, as well as the influx of Sogdians during the Sui-Tang, and later the arrival of large numbers of Muslims with the Mongolian Yuan. In other words, the shape of modern China on the edges came into being between 300 AD and 1300, as a small proportion of very exotic West Eurasian ancestry became the norm on the North China plain, while a large proportion of far less exotic and quite similar non-Chinese people were instrumental in the development of a distinctive southern Han people, based around particular localities and dialects.
The more interesting story will probably be in the Neolithic, around the time of the rise of agriculture on the North China plain (and in the Yangzi basin).