Razib Khan One-stop-shopping for all of my content

May 6, 2019

The emergence of Han identity as autochthonous

Filed under: China,Historical Population Genetics,Sino-Tibetan — Razib Khan @ 10:00 pm

Reader Matt points me to two new papers on the linguistic phylogenetics of the Sino-Tibetan language families, Dated language phylogenies shed light on the ancestry of Sino-Tibetan and Phylogenetic evidence for Sino-Tibetan origin in northern China in the Late Neolithic. You should read Matt’s whole comment, but one thing he mentions is that by ~3,000 years ago, individuals who were genetically similar to modern Burmese were already present in the territory of modern Burma. Burmese are quite distinct from Cambodians or Vietnamese because there is a distinct “northern” element, which perhaps resembles Tibetans.*

Matt observes that this means the expansion of agriculture into Southeast Asia occurred through a few pulses in rapid succession, rather than gradually over time, as seems likely the case in Europe and South Asia (“Early European Farmers” to Corded Ware, or Iranian agriculturalists to Central Asian agro-pastoralists). Austro-Asiatic speaking groups pushed out from the highlands of southern China 4-4,500 years ago. Meanwhile, people from further north seem to have pushed into the uplands of the western portion of upland Southeast Asia 500 to 1,000 years after this. Further east, Austronesians were sweeping along the coast and expanding into the maritime fringe.

But I am not intending to talk about Southeast Asia. Rather, I want to focus on China. Or perhaps more precisely the region and cultures that became China. Both the above papers suggest that the diversification of the  Sino-Tibetan languages occurred around ~7,000 years ago. And, that they began expanding from the zone of inland China, the upper Yellow River basin, from the area occupied by the Yangshao culture. This would explain some peculiar genetic facts. First, the northern affinities of Tibeto-Burman groups in northeast India and in Burma itself (which might otherwise require later Tai migrations) mentioned above. But second, about ten years ago when the early work on EPAS1 and high altitude adaptation was done on Tibetans, their genetic relatedness to Han Chinese was surprisingly close! In fact, some estimate of divergence put it as recently as 3,000 years before the present (I think this was an underestimate, but it gets at the qualitative result).

Remember, this was still before the massive swell of publications which have transformed our understanding of the ubiquity of migration, admixture, and demographic expansion in the recent past across the Holocene. Today I suspect the best model to explain these affinities are that people on of modern greater Tibet descend in large part from the “Yangshao Diaspora,” and amalgamated with local peoples, whether indigenous hunter-gatherers of the plateau region or Indo-Europeans moving in from the west.

I’ll spare you the Bayesian phylogenetics, and the cautions about relying too much on lexicons (see a discussion on The Insight for more). But one interesting aspect of the trees generated by both papers is that the Chinese language tends to be basal in its position in relation to most of the other languages, and the region of China itself is relatively low in linguistic diversity. The basal position and the presence of core words which are associated with the millet zone of north-central China indicate that frontier Tibeto-Burman groups separated long ago from the ancestors of the Chinese dialects. The low linguistic diversity of China can be understood as a consequence of the Chinese Empire, which underwent demographic expansion from the Yellow River basin, and assimilated peripheral peoples over time (some of the southeast Chinese dialects suggest substrate influences).

Which brings me to the Yangshao culture and its centrality to the main stem of East Asian history. It flourished until 3000 BC. It was succeeded by the Longshan culture, which persisted until 1900 BC. Finally, the last great prehistoric culture of the region is the Erilitou. Due to both the oracle bones and various astronomical events associated with events recorded in Chinese history, history as such begins in the centuries before 1000 BC.

As you likely know, much of China proper was not Sinicized until after the fall of the Han dynasty. Deep into historical time the Yangzi river valley and Sichuan were culturally liminal to the orbit of the expanding Chinese civilization, but not of it (perhaps like early Macedonia, influenced by the more complex civilization, but still distinct and barbaric). Further south the territory had more in common ethnolinguistically with much of Southeast Asia. The Sinicization of the south that occurred in the period between 0 and 1000 AD was not just cultural, but also demographic. Looking at modern Chinese their genetic variation for the Han is quite a bit lower than many might expect. The Han of provinces such as Guangdong in the far southeast is not closer to the Vietnamese than they are to the Han of the Yellow River plain, despite geographic proximity to the latter (some of this might simply be due to homogenizing gene flow back and forth).

An aspect of East Asian historical demography and genetics that stands out to me is that in China itself there isn’t a very strong signature of admixture between distinct lineages that you see in Europe or South Asia (or even West Asia). By this, I mean the fact that the Uygurs are about 50/50 West and East Eurasian. Or that South Asians are mixed between West Eurasians and an ancient indigenous lineage. Or, that the disparate West Eurasian ancestors of Europeans, and the Basal Eurasian component, were all quite distinct before being threaded together. True, many northern Han have detectable West Eurasian ancestry (5% or less), but I think this can be attributed to Turkic and Mongolic peoples, who have higher fractions of this ancestry (probably from Indo-Europeans that they absorbed).

Modern Chinese show much more affinity to the Devil’s Gates samples from the northeastern border with Russia dated to 7,700 years ago than modern Western Europeans do with people present 7,700 years ago (or modern Indians would with people of a similar date). This may illustrate the particular geographic advantages of the upper Yellow River basin over 4,000 years, from 3000 BC down to 1000 AD, when both Chinese economic and cultural power shifted to the Yangzi river valley**. The arrival of the light chariot after the 2000 BC attests to contacts to the west, but the genetic imprint has always been relatively minor. Contrast this to the vast steppe zone between Pannonia and the Altai, where there were multiple reflux events as peoples migrated in both directions at various peoples.

China is different from the other nations of the Eurasian oikomene. The “Rimland.” Some of this goes very deep, and probably the best understanding has to involve a consideration of the physical and human geography of the region, and its relative isolation from broader forces in Eurasian history.

Many peoples claim to be autochthons. The ancient Athenians for example. But the people of the Han civilization developing in the centuries after 1000 BC in the Yello River basin could likely make a more plausible case of being descendants of local hunter-gatherers who were “always there”, and eventually settled down to farm.

* One of the reasons I am convinced that Bengalis have Tibeto-Burman, and not simply Austro-Asiatic, East Asian ancestry is that this northern component can be seen in modern Bengalis, who are about 5-20% East Asian in ancestry.

** The economic power had shifted by 700 AD, but Xian in the north remained the capital until the fall of the Tang.

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