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September 25, 2018

A clash of civilizations along the lower Mekong

Filed under: Cambodia,Mainland Southeast Asia,Southeast Asia,Vietnam — Razib Khan @ 12:16 am

The lower Mekong region is a fascinating zone from the perspective of human geography and ethnography. Divided between Cambodia and Vietnam, until the past few centuries it was, in fact, part of the broader Khmer world, and historically part of successive Cambodian polities. Vietnam, as we know it, emerged in the Red River valley far to the north 1,000 years ago as an independent, usually subordinate, state distinct from Imperial China. Heavily Sinicized culturally, the Vietnamese nevertheless retained their ethnic identity.

Vietnamese, like the language of the Cambodians, is Austro-Asiatic. In fact, the whole zone between South Asia and the modern day Vietnam, and south to maritime Southeast Asia, may have been Austro-Asiatic speaking ~4,000 years ago, as upland rice farmers migrated from the hills of southern China, and assimilated indigenous hunter-gatherers.

But the proto-Vietnamese language was eventually strongly shaped by Chinese influence. This includes the emergence of tonogenesis. Genetically, the Vietnamese are also quite distinct, being more shifted toward southern Han Chinese and ethnic Chinese minorities such as Dai. My personal assumption is that this is due to the repeated waves migration out of southern China over the past few thousand years, first by Yue ethnic minorities, and later by Han Chinese proper. Many of these individuals were culturally assimilated as Vietnamese, but they clearly left both their biological and cultural distinctiveness in what was originally an Austro-Asiatic population likely quite similar to the Khmer.

As I have posted elsewhere it is also clear to me that Cambodians have Indian ancestry. Because unlike Malaysia Cambodia has not had any recent migration of South Asians due to colonialism, the most parsimonious explanation is that the legends and myths of Indian migration during the Funan period are broadly correct. There is no other reason for fractions of R1a1a among Cambodian males north of 5%. Depending on how you estimate it, probably about ~10% of the ancestry of modern Cambodians is South Asian (the Indian fraction is easier to calculate because it is so different from the East Asian base).

This is present in a few Vietnamese (Kinh) samples I have seen, but it is at a lower frequency. The reason for this Indian ancestry is that southern Vietnam became Vietnamese only in the last 500 years, and more intensively only in the last 200 years. The Vietnamese with Indian ancestry are almost certainly people who are from the southern part of the country with Khmer, or Cham, heritage.

Viet Nam: A History from Earliest Times to the Present is divided into three broad periods. The first is the development of the Vietnamese people as a synthesis of external elements from the north, and the Austro-Asiatic “sons of the soil.” Roughly from the Trung sisters down to the emergence of an independent Vietnamese state in the decades before 1000 AD. This is a narrative of perseverance. Unlike the Yue people of Guangdong and Fujian (and parts further north), the Vietnamese maintained their ethnic identity through long periods of Chinese rule. Transformed and reshaped by the Chinese rule, they emerged from it inflecting Sinic cultural elements within their own traditions.

The second phase is one of conquest. To some extent to an American who is used to seeing the Vietnamese as being catspaws in 20th-century geopolitics, it is painful to read about the drive south of the Vietnamese, and their extermination and assimilation of the earlier peoples and polities. Though they did not use a word such as “Manifest Destiny,” with hindsight it was clear that the Vietnamese were going to push along the coast southward until someone stopped them by force. As it happened, the rise of Vietnam coincided with the decline of Cambodia.

In the 18th and early 19th centuries, Vietnam and Siam (what became Thailand) fought over Cambodia in a manner analogous to occurred with Poland in the same period. The Vietnamese rule of Cambodia, especially in the first half of the 19th century, was concurrent with a drive toward more punctilious Confucianization of Vietnamese society along with a drive to forcing Buddhism into the private domain. This Confucianization entailed reinforcement of patriarchal rules, as well as attention to matters of uniform dress. The Vietnamese monarchy was attempting to create a Confucian society ruled by virtuous bureaucrats, overseeing a populace aware of and cognizant of the proper civilized forms.

Though never as extreme as Korea, Vietnamese Confucianism during this period was probably more pervasive than it ever became in Japan (where formal Confucianism tended to be the purview of the samurai class during the Tokugawa age). As part and parcel of civilizing Cambodia, making it Vietnamese, the conquerors attempted to do with the Khmer what they had done to their own people. Diminish the role and prominence of institutional religion, in this case, Theravada Buddhism, and educate the populace so that they could begin to produce their own virtuous bureaucrats.

One of the most interesting and curious aspects of the Vietnamese rule of the Cambodians is that the comments by the ruler of Vietnam and his subordinates clearly show some deep lack of the understanding of the distinctive nature Khmer culture as opposed to Vietnamese, in particular, northern Vietnamese, culture. They complain that though the Khmer maintain outward forms of proper decorum, they seem not to internalize the forms in a manner that would indicate they are sincerely civilized. The Vietnamese ruler marvels that the Cambodians have 1,200 years of history, but lack precise dates on their origins, and have vague dynastic periods (this is, to be frank, a very Indian feature). Additionally, the Khmer seemed obstinately attached to their Theravada Buddhist religion. When they rebelled against their Vietnamese overlords with the aid of Siamese invaders they declared that they did so to defend the Three Jewels of Buddhism. As is common in China, Vietnamese Buddhist sects periodically rebelled. But these rebellions were sectarian. In Cambodia Buddhism was not a sect, to be a Cambodia was to be a Theravada Buddhist.

In frustration, the Vietnamese ruler declared that “moral suasion” simply does not work with the Khmers! Though his regime was brutal, he was ultimately a Confucian who assumed exhortation would win out in the end.

Though the Vietnamese were aware of the cultural differences between themselves and the Khmer, they were not prepared for the task of swallowing a whole civilization distinct from their own.

This brings to mind comments of Victor Liberman, a scholar of mainland Southeast Asia, that Vietnamese Sinic Confucian statecraft was qualitatively different from the “solar polities” to its west. In his book Strange Parallels Southeast Asia in a Global Context, he outlines what he believes to be the features of these societies which allowed them to emerge in the early modern period with nation-states in a manner recognizable to Europeans. Over most of Southeast Asia Indian high culture spread in the period before 1000 AD (in fact, it was dominant in the southern two-thirds of modern Vietnam before 1500 AD). This meant the emergence of relatively politically loose societies around the charismatic figure of a monarch whose legitimacy was fundamentally religious and metaphysical. Southeast Asian kings aspired to be cakravartin. The turners of the wheel of history.

In contrast through steps and starts the Vietnamese developed a society which was in many ways a miniature shadow of that of China to the north. Instead of a divinely sanctioned monarchy, Vietnam produced subordinate kings to the emperor of China or in some cases a ruler who declared he was an emperor himself.  Their rule was sanctioned not by gods or priests, but impersonal Heaven and its mandate.

Whereas other Southeast Asian monarchs had court brahmins, bhikkhus, and later in the Malayan world ulema, the Vietnamese monarchs often put away the Buddhist monks and priests and hid any religious devotion from public view. On the Chinese model, the Vietnamese drove religion away as a helpmate, and subordinated religious impulse as ancillary to state functions and transformed it primarily to something that was a matter of popular enthusiasm and private devotion. Like the Chinese, the Vietnamese polity aimed to recruit and produce a large and broad class of virtuous administrators, many drawn from the agricultural populace itself to main social order and proper state function.

Liberman observes that the Chinese model necessarily requires greater coordination, concentration, and mobilization. Additionally, there naturally develops a cultural chasm between the simple peasant, and the educated bureaucrat, in such a society. In contrast in solar polities, the king and high nobility may be distant from the people as symbols, but the vast mass of peasants and clerics interact and engage on a popular level. Religious truths and ideals often can propagate on a dimension closer to the masses than the culture of the Confucian literati. While efficient and constitutive mobilization of the resources of solar polities is low at any given time, mass enthusiasm may be easy to trigger in punctuated bursts of activity around charismatic figures and exigent circumstances.

March 9, 2018

Demographic replacement in Southeast Asia during the Holocene

Filed under: Human Population Genetics,Southeast Asia — Razib Khan @ 12:15 am

Well sometimes you feel silly, and it’s not your fault. Yesterday our podcast on Sundaland went live (we talked about Doggerland and Beringia too!). Though I expressed a fair amount of skepticism, I took the argument that Stephen Oppenheimer presented in Eden of the East, that modern Austronesians are long-term residents of Southeast Asia, seriously.

The alternative view, most forcefully put by Peter Bellwood in books such as First Farmers, is that Austro-Asiatic and Austronesian people were agriculturalists issuing out of southern China that transformed the region over the past 4,000 years (the Austronesians from Taiwan specifically, though during the Pleistocene Taiwan was connected to the mainland).

I lean toward Bellwood’s view, and today a preprint came out which basically confirms it in totality, Ancient Genomics Reveals Four Prehistoric Migration Waves into Southeast Asia. The abstract:

Two distinct population models have been put forward to explain present-day human diversity in Southeast Asia. The first model proposes long-term continuity (Regional Continuity model) while the other suggests two waves of dispersal (Two Layer model). Here, we use whole-genome capture in combination with shotgun sequencing to generate 25 ancient human genome sequences from mainland and island Southeast Asia, and directly test the two competing hypotheses. We find that early genomes from Hoabinhian hunter-gatherer contexts in Laos and Malaysia have genetic affinities with the Onge hunter-gatherers from the Andaman Islands, while Southeast Asian Neolithic farmers have a distinct East Asian genomic ancestry related to present-day Austroasiatic-speaking populations. We also identify two further migratory events, consistent with the expansion of speakers of Austronesian languages into Island Southeast Asia ca. 4 kya, and the expansion by East Asians into northern Vietnam ca. 2 kya. These findings support the Two Layer model for the early peopling of Southeast Asia and highlight the complexities of dispersal patterns from East Asia.

The transition to full-fledged rice agriculture occurred in Vietnam ~4,000 years ago. In First Farmers Bellwood reports on an archaeological site dating to that period where skeletal evidence has been adduced to record the presence of both Northeast Asian and Australo-Melanesian types. These results make clear though that these hunter-gatherers in Southeast Asia are more similar to the Onge of the Andaman Islands, as well as the Negritos of the interior of the Malay peninsula. They’re totally in alignment with the earlier morphological results (also, readers might be curious to know that one site of the Hoabinhian culture is in Yunnan, China). This shouldn’t be surprising, as the Andaman Islands were a peninsula which extended from southern Burma during the Pleistocene.

Already the most accepted model for the introduction of intensive agriculture into Southeast Asia is that it was brought by Austro-Asiatic peoples. These results confirm that. Additionally, it seems clear that Austro-Asiatic ancestry made it to island Southeast Asia, whether directly or through Austronesian admixture before arriving in island Southeast Asia. Java and Bali have some of the higher fractions ancestries most closely associated with Austro-Asiatic groups on the mainland.

Deeper digging into the admixture distributions has long made it pretty evident that some areas had much higher Austronesian fractions in Indonesia than others, and it wasn’t just a function of distance from the Phillippines. Why? My own hunch is that Austronesians brought social and cultural systems which were better adapted to island Southeast Asia, and were more fully able to exploit the local ecology. Meanwhile, aside from a few fringe areas such as the Malay peninsula and coastal Vietnam, they were not successful on the mainland.

The authors also detect migrations into Southeast Asia besides that of the Austro-Asiatics and Austronesians. One element seems correlated with the Tai migrations, and another with Sino-Tibetan peoples, most clearly represented in Southeast Asia by the Burmans. The excellent book, Strange Parallels: Volume 1, Integration on the Mainland: Southeast Asia in Global Context, c.800–1830, recounts the importance of the great migrations of the Tai people into Southeast Asia ~1000 A.D. Modern-day Thailand was once a flourishing center of Mon civilization, an Austro-Asiatic people related to the Khmers of Cambodia. The migrations out of the Tai highlands of southern China reshaped the ethnography of the central regions of mainland Southeast Asia. The Tai also attempted to take over the kingdoms of the Burmans. Though they failed in this, the Shan states of the highlands are the remnants of these attempts (tendrils of the Tai migrations made it to India, the Ahom people of Assam were Tai). Vietnam, shielded by the Annamese Cordillera, came through this period relatively intact. It is also well known that Cambodia’s persistence down to the present has much to do with the shielding it received from France in the 19th century in the wake of Thai expansion.

There are two bigger issues that this paper sheds light on. One is spatial, and the other is temporal.

They detect shared drift between Austro-Asiatic people and tribal populations in northeast India. This is not surprising. A 2011 paper found that Munda speaking peoples, whose variant of Austro-Asiatic is very different from that of Southeast Asia, are predominant carriers of Y chromosome O2a. This is very rare in Indo-European speaking populations, and nearly absent in Dravidian speaking groups. Additionally, their genome-wide patterns indicate some East Asian admixture, albeit a minority, while they carry the derived variant of EDAR, which peaks in Northeast Asia.

One debate in relation to the Munda people is whether they are primal and indigenous, or whether they are intrusive. The genetic data strongly point to the likelihood that they are intrusive. An earlier estimate of coalescence for O2a in South Asia suggested a deep history, but these dates have always been sensitive to assumptions, and more recent analysis of O2a diversity suggests that the locus is mainland Southeast Asia.

Now that archaeology and ancient DNA confirm Austro-Asiatic intrusion into northern Vietnam ~4,000 years ago, I think it also sheds light on when these peoples arrived in India. That is, they arrived < 4,000 years ago. As widespread intensive agriculture came to Burma ~3,500 years ago, I think that makes it likely that Munda peoples arrived in South Asia around this period.

I now believe it is likely that the presence of Austro-Asiatic, Dravidian, and Indo-Aryan languages in India proper was a feature of the period after ~4,000 years ago. None of the languages of the hunter-gatherer populations of the subcontinent remain, with the possible exception of isolates such as Nihali and Kusunda.

The temporal issue has to do with the affinities of these peoples, and how they relate to the settling of Eastern Eurasia. All the Southeast Asian groups after the original Australo-Melanesians share more of an affinity with the Tianyuan individual than Papuans. The implication here is that Tianyuan is closer to the ancestors of various agriculturalists in Southeast Asia than just some random basal Eastern Eurasian. But, since Tianyuan dates to 40,000 years ago, and, is from the Beijing region, it is hard to make strong inferences from comparisons with only it. The heartland of ancient Chinese culture in Henan was to the south of the Tianyuan, after all. More samples are needed before one can truly tease out the pattern of isolation-by-distance vs. admixture that led to the emergence of the proto-farmer populations which settled Southeast Asia.

In the podcast above one thing that came up is that a lot of genetic data indicate decreased diversity as one moves from the south to the north in East Asia. This has long been taken to mean that humans migrated north, and so were subject to bottleneck effects. I pointed out that this may simply be a consequence of admixture between two very different groups of people in Southeast Asia, elevating diversity statistics.

And yet as the map at the end of the preprint suggests it is highly plausible that Pleistocene Asia was marked by a south to north dynamic of migration. The Austro-Asiatic peoples who migrated south during the Holocene may simply have been backtracking the migration of their ancestors. What these results, and ancient DNA more generally, tell us is that humans were often on the move. The Pleistocene world of climate change probably meant that humans had to be on the move.

September 7, 2017

South Asian gene flow into Burmese and Malays?

Filed under: Burma,Genetics,Malaysia,Southeast Asia — Razib Khan @ 10:22 pm


I happen to have a data set merged from the 1000 Genomes and Estonian Biocentre which has Malays, Burmans, and other assorted Southeast Asians, East Asians, and South Asians. In light of recent posts I thought I would throw out something in relation to this data set (you can download the data here). Above you can see the populations in the data. You see Bangladeshis consistently are shifted toward Southeast Asians in comparison to other South Asians. But both Burmans and Malays exhibit some shift toward South Asians.

I ran ADMIXTURE at K = 4. Click the image for the larger file which shows the populations, but I will tell you what’s going on.

The yellow to green represent a north-south axis in East Asia. The Han sample is mostly yellow, but there is a green component in varying degrees. This almost certainly represents heterogeneity in the Han sample of north to south Chinese. The green component is nearly ~100% in some individuals from indigenous tribes in Borneo, and balanced with the yellow among peninsular Malays. It is more at a higher frequency in Cambodia than in Vietnam or Burma, indicating the older roots of Khmers and their relative insulation from later migrations of Sino-Tibetan and Tai peoples.

The red South Asian component is found in many Southeast Asians, but curious in the Burmans and Malays there is a lot of variation within the population. That indicates admixture over time that has not homogenized throughout the population.

I ran Treemix with 5 migration edges and French rooted (1000 SNP blocks out of 225,000 SNPs) and they all looked like this. Commentary I will leave to readers….

March 11, 2012

The Indonesian cline

Filed under: Genomics,Human Genetics,Human Genomics,Southeast Asia — Razib Khan @ 1:34 pm

Dienekes has touched upon it in detail, so I don’t have much to add. Except for two points:

1) The ancestry cline here is not due to isolation-by-distance, but the expansion of the Austronesian population rather precipitously ~4,000 years ago. As Dienekes observed this was rather clear by non-genetic means; this is just icing on the cake.

2) There is evidence of an Austro-Asiatic substrate across maritime Southeast Asia. For whatever reason it seems that Austro-Asiatic speaking agriculturalists ceased their push east at the Wallace Line.

July 23, 2011

Southeast Asian migrations, Indians and Tai

If you have not read my post “To the antipode of Asia”, this might be a good time to do so if you are unfamiliar with the history, prehistory, and ethnography of mainland Southeast Asia. In this post I will focus on mainland Southeast Asia, and how it relates implicitly to India and China genetically, and what inferences we can make about demography and history. Though I will touch upon the Malay peninsula in the preliminary results, I have removed the Indonesian and Philippine samples from the data set in totality. This means that in this post I will not touch upon spread of the Austronesians.

I present before you two tentative questions:

- What was the relationship of the spread of Indic culture to Indic genes in mainland Southeast Asia before 1000 A.D.?

- What was the relationship of the spread of Tai culture to Tai genes in mainland Southeast Asia after 1000 A.D.?

The two maps above show the distribution of Austro-Asiatic and Tai languages in mainland Southeast Asia. Observe that when you join the two together in a union they cover much of the eastern 2/3 of mainland Southeast Asia. ...

July 21, 2011

Asian Negritos are not one population


Negrito, Philippines. Credit: Ken Ilio

In the post below I mentioned that the Malaysian and Philippine Negritos seem to be two very distinct populations. This was something I wanted to explore in more detail, so I naturally decided to poke around the Pan-Asian SNP data set. The aims are made somewhat more difficult by the fact that there are only ~56,000 markers in the data set (as opposed to ~600,000 in the HGDP and more than 1 million in the HapMap). Additionally, the intersection with other data sets is small. For example, only ~20,000 SNPs with the HGDP. With all that in mind I hazarded that something is better than nothing. Relatives and HapMap populations were removed from the data set (thanks Zack). Additionally, I beefed up the South Asian populations with the Gujaratis from the HapMap,which had an intersection of ~32,000 SNPs. After a few test runs I decided to remove the Mlabri. They always shook out very early as a separate population from many others nearby, and, their genetic distances were very high. This tribe is only numbered in the hundreds, ...

July 20, 2011

Bacteria tell the tale of human intercourse

Filed under: Anthroplogy,Austro-Asiatic,Genetics,H. pylori,Medicine,Southeast Asia — Razib Khan @ 12:39 am

The Pith: the genetic relationships between bacteria in our stomach can tell us a lot about the relationships between various groups of people. Additionally, the distribution of different strains of bacteria may have significant public health implications.

The above image is from a paper which was pushed online yesterday in PLoS ONE: Evolutionary History of Helicobacter pylori Sequences Reflect Past Human Migrations in Southeast Asia. It’s a paper which caught my attention for several reasons. First, I’ve exhibited some curiosity about the history and prehistory of Southeast Asia of late. Elucidating this region’s historical dynamics may bear upon more general questions of human evolutionary and cultural process. Second, H. pylori is a fascinating organism whose connection to specific human populations is tight enough that it can shed light on past interactions of different groups. In short, just like humans H. pylori exhibits regional specificity and local history. But additionally, H. pylori is also subject to natural selection after introduction into a new population, and so can serve as a window upon cultural contacts which might otherwise leave a light demographic footprint. In other words, the spread of ...

July 18, 2011

To the antipode of Asia

Markers show populations sampled by HUGO Pan-Asian SNP Consortium

The Pith: Southeast Asia was settled by a series of distinct peoples. The pattern of settlement can be discerned in part by examination of patterns of genetic variation. It seems likely that Austro-Asiatic populations were dominant across the western half of Indonesia before the arrival of Austronesians.

About a year and a half ago I reviewed a paper in Science which did a first pass through some of the findings suggested by the HUGO Pan-Asian SNP Consortium data set, which pooled a wide range of Asian populations. You can see the locations on the map above (alas, the labels are too small to read the codes). The important issue in relation to this data set is that it has a thick coverage of Southeast Asia, which is not well represented in the HGDP. Unfortunately there are only ~50,000 markers, which is not optimal for really fine-grained intra-regional analysis in my opinion. But better than nothing, and definitely sufficient for coarser scale analysis.

A few things have changed since I first reviewed this paper. First, I pulled down a copy ...

June 15, 2011

Language, genes, & peoples of Southeast Asia

As I am currently reading Victor Lieberman’s magisterial Strange Parallels: Volume 2. So I was very interested in a new paper from BMC Genetics, Genetic structure of the Mon-Khmer speaking groups and their affinity to the neighbouring Tai populations in Northern Thailand, pointed to by Dienekes today. Here are the results and conclusions:

A large fraction of genetic variation is observed within populations (about 80% and 90 % for mtDNA and the Y-chromosome, respectively). The genetic divergence between populations is much higher in Mon-Khmer than in Tai speaking groups, especially at the paternally inherited markers. The two major linguistic groups are genetically distinct, but only for a marginal fraction (1 to 2 %) of the total genetic variation. Genetic distances between populations correlate with their linguistic differences, whereas the geographic distance does not explain the genetic divergence pattern.

The Mon-Khmer speaking populations in northern Thailand exhibited the genetic divergence among each other and also when compared to Tai speaking peoples. The different drift effects and the post-marital residence patterns between the two linguistic groups are the explanation for a small but significant fraction of the genetic variation pattern within and between them.

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