The Neolithic roots of modern East Asian human geography

Because of the long and thorough tradition of Chinese historiography, we have a good and deep chronological record of East Asia going back two to three thousand years ago. Chinese records also help illuminate and clarify aspects of Japanese, Korean, and Southeast Asian, history. For example, what we know about the Indianized kingdom of Funan in eastern mainland Southeast Asia is from textual sources are Chinese.

But, history can take us only so far. We know this for Western Eurasia, where ancient DNA has revolutionized our understanding of Holocene transformations. Unfortunately, we don’t have that much ancient DNA from East Asia. So we still have to make recourse mostly to modern data. A new preprint proposes to use a lot of modern (and some ancient) data to answer a very specific question, Inland-coastal bifurcation of southern East Asians revealed by Hmong-Mien genomic history. The basic results are totally unsurprising:

Consistent with the two distinct routes of agricultural expansion from southern China, this Hmong-Mien founding ancestry is phylogenetically closer to the founding ancestry of Neolithic Mainland Southeast Asians and present-day isolated Austroasiatic-speaking populations than Austronesians. The spatial and temporal distribution of the southern East Asian lineage is also compatible with the scenario of out-of-southern-China farming dispersal. Thus, our finding reveals an inland-coastal genetic discrepancy related to the farming pioneers in southern China and supports an inland southern China origin of an ancestral meta-population contributing to both Hmong-Mien and Austroasiatic speakers.

More interesting to me is the admixture graph to the right. It uses a bunch of ancient and modern populations to model ancient and modern populations. You can see some general patterns and suggestions of what might come out fo ancient DNA.

For example, the green component is defined by the Hoabinhian samples. These are the people who are distantly related to the Andaman Islanders, and occupied Southeast Asia before the arrival of rice farmers. They are distantly related to “Ancient Ancestral South Indians” (AASI) as well. It is unsurprising that this component is well represented in a Munda tribe (Kharia) from northeast India, or in Austro-Asiatic people of Southeast Asia. But notice that it is well represented in the Jomon of Japan, and modern Tibetans.

If you read the preprint, the authors clearly don’t think that this is Hoabinhian ancestry as such. Rather, the model is looking for something very basal (distant) from other East Eurasians, and Hoabinhians fit that (and are somewhat closer to this basal group). This is probably the same phenomenon of “Australo-Melanesian” ancestry in the Amazon. Curiously, Y haplogroup D is found in Tibet, Japan, and the Andaman Islanders.

The largest group in East Asia are Han Chinese and can be modeled as an admixture of the ancient Northeast Asian Devil’s Gate Cave people and modern Ami Taiwanese aboriginals (Austronesians). This is basically a north-south cline. One doesn’t need to posit obviously that the modern Han is truly a mix of these two groups, but rather that Han identity emerged out of a synthesis of various Neolithic groups with differential affinities to these two groups.

Two ancient samples give a good picture of how these groups are related to West Eurasians. The Afanasevio was almost exactly like the Yamnaya. The Namazga sample comes from ancient prehistoric Khorasan, on the border of modern Iran and Turkmenistan. These two samples do have some affinities with each other. Both have ancestry that related to or derived from “Ancestral North Eurasians” (ANE) and “Caucasus Hunter-Gatherers” (CHG), with the Yamnaya having more ANE and Namazga more CHG. But the Yamnaya also had affinities with “Western Hunter-Gatherers” (WHG) that Namazga lacked. You see that the Kharia has affinities to Namazga, but not Afanasevio. This is not surprising: the Munda tribes of Northeast India seem almost untouched by Indo-Aryan influence (they are entirely lacking in R1a1a, which is found in South Indian tribals). Rather, they mixed with Indian populations which were impacted by migrations of farmers from West Asia.

The proportion of Afanasevio and Namazga are illustrative of particular historical dynamics. Mongols and Xiongnu (ancient) had some connection to the Afanasevio. This is almost certainly Indo-European (probably East Iranian) contact. In contrast, the Hui, Chinese Muslims who are mostly no different from Han aside from religion, have contributions from both Afanasevio and Namazga. This is a strong indication that Hui do have more recent Central Asian (Muslim) ancestry, while Mongolians do not. The increase in Namazga ancestry across Central Asia is probably a function of the rise of Persian and Islamic polities, and the movement north of agriculturalists. The shift to Turkic dominated polities integrated Turan with the rest of the Islamic steppe, which happens to exclude the Mongolians.

It is also interesting that the Thai have more Namazga than Khmer. This is strongly suggestive of a large contribution of Indian ancestry to the Dvaravati culture (the enrichment for Devil’s Cave in the Khmer is probably due to the reality that a few of the HGDP samples seem to be mixed with Chinese), though it could be more recent admixture from India. Note however that the Mon people of Burma seem to have more Indian ancestry, and were often associated with Dvaravati.

Finally, the authors point out that the red southern Northeast Asian component is now common in peoples like the Koreans and Japanese. A clear indication of the spread of farming from southern people, as well as the likely later demographic impact of the expansion of the Chinese state and its spillover impact on Korea.