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51KHpfTVbiL._SY344_BO1,204,203,200_ Let’s start at the beginning. If you read a book about Indian history in the 1980s it might begin with this sort of stylized narrative: in the beginning were the Mundas. Then there were the Dravidians, then finally the Aryans (and as an afterthought various East Asian groups on the fringes of northern and eastern Aryavarta). The thesis, broadly, was that the Munda people, who speak an Austro-Asiatic language, were the closest that the Indian subcontinent had to genuine aboriginals. The oldest of old. Supporting this contention is the fact that the languages of the Munda people, with distant affinities to Cambodian and Vietnamese, are very alien in comparison to Dravidian and Indo-Aryan (if Dravidian has any connections outside of the subcontinent, they are always posited to the west, in ancient Iran. The Munda languages clearly have eastern connections). The supposition then was that from the Munda arose various peoples of eastern Eurasia. To cut to the chase this model is probably wrong. The genetic structure of South Asia seems to have arrived at its current outlines relatively recently. In regards to the Munda people their origin is in Southeast Asia. They are not the progenitors of Southeast Asians, they are in part derived from Southeast Asians. Part of the broader expansion of “first farmers” in Southeast Asia from southern China. Their Y chromosomal lineages and autosomal heritage both imply this. Additionally, they carry the Northeast Asian derived variant of EDAR. Though much of their culture is almost certainly exogenous, and of relatively recent vintage, they are clearly highly admixed with the South Asian substrate. In particular, the fusing of an ancient West Eurasian population (“Ancestral North Indians”, or ANI) and a deeply rooted indigenous group with distant affinities further east (“Ancestral South Indians”, or ASI).

Chaubey, Gyaneshwer, et al. "Population genetic structure in Indian Austroasiatic speakers: the role of landscape barriers and sex-specific admixture." Molecular biology and evolution 28.2 (2011): 1013-1024.

Chaubey, Gyaneshwer, et al. “Population genetic structure in Indian Austroasiatic speakers: the role of landscape barriers and sex-specific admixture.” Molecular biology and evolution 28.2 (2011): 1013-1024.

One of the reasons that the ancient character of Munda residence in South Asia was persuasive is that they are resident in upland zones, which perhaps refuges after being marginalized by later arrivals. Their fragmented distribution is a tell that they occupied wider territories than is the case today. One thesis is that the Gangetic plain was inhabited by Munda people before the Indo-Aryans arrived. Rather than Dravidians, the indigenes in the Vedas may have been Mundas. But I’m interested in a more parochial question: can Munda ancestry explain the high fraction of East Asian ancestry in Bengalis, particular eastern Bengalis?

We can address this question a bit with genetics thanks to the resources we have in terms of population coverage. As readers know I’ve started to work with the 1000 Genomes data set. Luckily it has a large number of Bengalis within it. Meanwhile, the Estonian Biocentre has put its genotype data online, and there are Munda samples in there. I merged the data together, and removed pretty much all missing alleles. At the end of it I had 185,000 SNPs. To explore the questions I had in mind I decided to look at several populations. Bengalis and Telegu speakers (their genetic position would put them as “middle castes”; not Brahmins, but not Dalits or tribals). Georgians (from the Caucasus) as an outgroup. For Southeast Asian groups, Burmese, Cambodians, Filipinos and Dai. Finally, a small number of Munda. I plotted them on a PCA and removed those individuals who were not easily assigned to a cluster. The first PCA: MundaPC1

This isn’t really telling you much you don’t know. Let’s look at PC 3 now: Rplot

As you can see the Munda show a cline toward the Cambodians. This makes sense if the Munda descend from Austro-Asiatic agriculturalists. The Austro-Asiatic expansion in Southeast Asia probably dates to 4,000 years ago or so. Peter Bellwood has stated that archaeologists have excavated villages in northern Vietnam which catch the process of ethnic transition in action at this date (e.g., 75% of the burials are of gracile individuals, whille 25% very robust individuals). Such dates might put a ceiling on how early the Munda arrived inthe Indian subcontinen. In these results the Filipinos are representative of Austronesians, who have their roots in Taiwan and the Fujian coast, while the Dai are the forerunners of the Thai who arrived in Southeast Asia over the last few thousand years, taking over the uplands of Burma (Shan) and Laos (Lao), and swallowing the Khmer civilization which once flourished in the Chao Phraya basin (becoming Thailand). But it’s hard to make out what’s going on with the Bengalis…to me it isn’t clear that they’re shifted as much toward the Cambodians as they should be if the Asian ancestry was due to Munda being absorbed by Indo-Aryan speaking farmers.

So next I ran Admixture. I ran supervised and unsupervised and they showed the same qualitative result. Below is a bar plot of the unsupervised result, K = 5.

plinkAA_htm_mf149510

The Munda ancestry which is Southeast Asian here is overwhelmingly Austro-Asiatic. That is not the case with the Bengalis, who exhibit a range of fractions. There is very little Austronesian ancestry, which is something one might expect. But, there’s a balance of Austro-Asiatic and Daic ancestry in many individuals, though there is inter-individual variation (my mother has one of the strongest Austro-Asiatic skews among the Bengalis, while my father is among the most Daic; previous runs of admixture consistently show that her eastern Eurasian is more Southeast Asian than his, which has suggestions of Northeast Asian). This is not consistent with Munda being the sole source of East Asian ancestry in modern Bengalis.1 Using rolloff based methods researchers have estimated that admixture into Bengalis occurred on the order of 1,000 years ago. There’s nothing here that would contradict that, and the admixture can easily be explained by the Burmese in the data above, or Khasi and Garo people, who live to north and and east of Bengalis.

Finally, I ran TreeMix on the data. I removed the Georgians and Filipinos because they didn’t add much. Additionally, for kicks I broke apart the Bangladeshis into two groups defined by the 25 most Daic, and 25 least Daic. Below are the ten plots from the ten runs.

MTree.9 MTree.10 MTree.1 MTree.2 MTree.3 MTree.4 MTree.5 MTree.6 MTree.7 MTree.8

I don’t think breaking apart the Bengalis did any good. There were runs with the full fused sample, and the results were similar. It is clear that TreeMix also suggests that Munda are not a singular donor to Bengalis of their East Asian heritage. The source of the donor migration arrow is always shifted more toward Southeast Asian groups proper. Breaking apart the Bengalis into Austro-Asiatic and Daic skewed groups did result in the source of the gene flow being somewhat different. But not appreciably. I also ran the f3 and f4 statistics. There’s nothing surprising about who mixes with who…though it is notable in these and the above results that Burmese show nearly as high a gene flow from South Asians as Bengalis show from Southeast Asians. There have long been suggestions of gene flow from India to Cambodia, perhaps associated with the ancient mediation of South Asian cultural forms across Southeast Asia. But the Burmese evidence of gene flow is tragically ironic in light of the fact that modern Burmese are virulently racist toward dark skinned Muslims who clearly have South Asian origins.

51MGYd330tL._SY344_BO1,204,203,200_ So what happened in Bengal? At the top of the post I have an illustration of The Rise of Islam and the Bengal Frontier, 1204-1760. The thesis of this book is that the Islamic nature of eastern Bengal is in large part due to its relatively recent settlement by Indo-Aryan farmers. Though Bengal has always been a marchland, on the fringes of Aryavarta, before the Islamic conquest of the 13th century its center of gravity, culturally and demographically, was in what is today in the Indian state of Bengal, to the west of Bangladesh. The author of The Rise of Islam and the Bengal Frontier, 1204-1760 suggests that Islamic elites were instrumental in opening up the lands to the east of the old core, and the peasant cultivators who came to cultivate the new territory under their leadership identified vaguely with the religious identity of this new elite (though in general practicing on a day to day level their own folk beliefs), as the old organically developed institutions of Hinduism and Buddhism were poorly moored in the virgin lands. To me this is reminiscent of Michelle Salzman’s data in The Making of a Christian Aristocracy, which suggests that Christian elites arose on the frontiers, rather than the old cores, under patronage of the new religious dispensation (these data are predicted by Peter Turchin in War and Peace and War). In contrast the old Roman elite was relatively late to Christianity, as they were attached their own customs and traditions, which had thick and deep roots in the heartlands of the Roman world. Similarly, Hinduism (or what became what we term Hinduism) between the Doab and western Bengal seems to have resisted Islam’s attempt to destabilize local institutions and interpose itself as the dominant religious ethos of the sub-elites. Only on the destabilized fringes of the west and east, where old orders did not exist or were totally torn down, did Islam find purchase as a majority dispensation.

Finally, the high component of East Asian ancestry among the peasants of eastern Bengal is probably a function of the fact that there were groups from the east also pushing into the fertile territory. If the initial population density was low then a modest inflow at the early stages, ~1,000 years ago, could have a major long term impact. The crushing population densities of “Golden Bengal” was centuries into the future. A lack of cultural memory of this admixture is curious, but to a great extent shifting to the new religion meant that the proto-east Bengalis were creating a new identity. Things get lost….

 
• Category: Science • Tags: Bangladesh, History 
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By now you are aware that another blogger who happened to be an atheist was killed. The modus operandi is pretty familiar. It looks like there are now “hits” going up against these individuals as a way for Islamic radicals to target an easy to scapegoat minority in Bangladesh. Atheists are now caught in a crossfire between religious nationalists and secularists, a divide which goes back to the Pakistan days. How vulnerable are the atheists? Well:

“The culture of impunity that has spread over the last few years clearly has very damning results,” Arifur Rahman told IHEU after Washiqur Rahman was killed. “… The word ‘Nastik’ (atheist) has been vilified in Bangladesh (and the rest of the Muslim world); they are seen as sub-human, it is OK to kill them.”

All cultures are not the same. In most of the Islamic world sufferance would be enough for many minorities. While craven Leftists wring their hands over insults to Islamic minorities in their midst, Islamic civilization is wrecking havoc upon the liberties of millions. That being said, there is a continuum. Saudi Arabia, Iran, Turkey, Malaysia, and Azerbaijan are not interchangeable. There are some analogies being made to Pakistan right now (like being analogized to Mississippi in the United States this is never good). That’s apposite at this particular moment because 45 Ismaili Muslims have been gunned down in Karachi. It strikes me that Pakistani sectarianism is now proceeding down a Bonhoefferian Niemöllerian gangplank, first dehumanizing non-Muslims, and then progressively narrowing the set acceptable. The nation is on the way to being a literal circular firing squad.

Bangladesh is a different case. I won’t rehash it. I will point out though that when I posted about my own identity, as an atheist of Bangladeshi origin, that when put that on reddit the response by one individual was “Who cares”? Obviously there are many things in Bangladesh that warrant attention, but, targeted killing of a reviled minority is apparently not worth notice by some. Fair enough, I suppose.

But I’m not here to emote and reflect. Rather, what does the data say? The World Values Survey has data from Bangaldesh for 1999 to 2004. One of the questions asks: Politicians who don’t believe in God unfit for public office. It seems a rough gauge for attitudes toward atheists. The results are below.

Atheist_htm_4ce6039

As you can see Bangladesh is roughly in the middle of the list. Observe the contrast with Pakistan. Hostility toward atheism is the majority position in all likelihood, but protests of people in the face of Islamist terror, as well as the persistence of atheists in Bangladeshi culture, indicates that there is a sufficient groundswell of liberal religious civil society that there’s a shot. In contrast in Pakistan you have a society which is now at total conformity when it comes to toleration for free thought.

Raw data:

Question: “Politicians who don´t believe in God unfit for public office”

Country Agree strongly Agree Neither agree or disagree Disagree Strongly disagree No answer Don’t know
Sweden 1.7 2.3 11.4 36.8 47.3 0 0.4
Spain 1.8 8.7 17 40.2 23.7 0 8.7
South Korea 2.6 6.7 27.3 37.5 15.4 0 10.5
Vietnam 4.5 11.9 16.9 47.4 5.8 0 13.5
Bosnia 5.1 10 30.2 25.5 22.2 0 7
Serbia 8.7 16.2 14 34.7 17.2 0 9.2
Canada 6.6 12 21.8 35.9 21.2 0 2.5
India 14.5 18.2 11.3 26.6 8.1 0 21.3
Chile 14 18.3 10 20.6 31.4 0 5.6
Japan 2.2 5.4 49.6 25.5 14.9 0 2.5
Mexico 14.9 21.5 9.2 27.3 16.2 0 10.9
Macedonia 17.7 14.7 16.8 27.5 16.6 0 6.8
Argentina 13.7 20.5 17 31.1 12.3 0 5.4
Kyrgyzstan 10.5 25 19.1 35.2 9.6 0 0.6
Moldova 11.7 28.9 21 24.1 5 0 9.2
Albania 16.1 24.8 24.7 19.2 7.2 0 8
United States 17.6 20.3 25.8 27.1 8.4 0 0.8
Zimbabwe 14.9 36.4 8.3 31.8 3.6 0 5.1
South Africa 22.9 24.6 19 19.9 7.1 0 6.5
Turkey 28.7 28.2 11.5 16.9 9.1 0.1 5.6
Venezuela 35.5 15.8 15.1 18.8 12.7 0 2.2
Uganda 25.2 36.2 14.3 17 4.3 0 3
Bangladesh 30.2 37 5.2 20 2.3 0 5.3
Puerto Rico 36.5 26.9 11.7 19.3 3.6 0.4 1.5
Tanzania 53.4 11.2 11 13.9 8.1 1 1.4
Philippines 26.8 44.4 14.7 11.9 1.9 0 0.2
Algeria 51.7 20.7 8 8.7 3.3 0 7.6
Jordan 66.6 11.1 2.1 6.8 9.3 0 4.1
Iraq 66.1 15.1 0 5.5 6.9 2.2 4.2
Nigeria 56.8 24.2 7.6 6.8 3.6 0 1
Indonesia 59.4 27.9 1.9 7.2 2 0 1.6
Morocco 72.4 14.2 2.7 4.3 1.2 0 5.1
Egypt 70.1 17.6 2.4 4.9 4.9 0 0
Pakistan 82.4 12.5 4 0.9 0.2 0 0
 
• Category: Foreign Policy, Ideology • Tags: Bangladesh, Religion 
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razib Years ago I recall a reader (perhaps Ikram or Conrad Barwa?) quip that I was basically Magid Iqbal from the novel White Teeth. Probably the biggest similarities are the fact that Magid is an atheist with a pro-Western outlook, and, he’s a geneticist. But a major difference is that the Magid depicted in White Teeth strikes me as a prig. And, there are obvious biographical discrepancies. Despite my parents threatening to send me back to Bangladesh periodically for impudence, they never did. I grew up in the United States, and have the citizenship of that country, as well as Bangladesh. And I’m quite glad to be an American right now, because of articles such as this: Atheists are being hacked to death in Bangladesh, and soon there will be none left. The sad conclusion:

This weekend I arrived in Bangladesh with the naïve hope of writing about wide-eyed idealists fighting the fight no matter what, fuelled with the zeal of Je Suis Charlie. The reality on the ground is much harsher: atheists are being hunted down for both religious retribution and political gain. Washiqur Rahman was right: words cannot be killed. But a struggling movement can only take so much battering, and Bangladeshi atheism is fighting to survive.

I’m not much interested in a “movement” of atheists. Bangladesh has other problems, and in some ways it is making progress. As I may have mentioned my mother was impressed and confused by the rapid economic development she saw across the country when visiting a few months ago (my parents left Bangladesh when the nation was only about a decade old). But these recent developments sadden me greatly, because when basic liberty of thought is an offense, then we see a society regressing. Mind you, I am not much the Whig, so this does not surprise me, nor does it strike me as unnatural. I think organized Islamism is atavistic in only a rhetorical sense. The reality is that it is a feature of modernity, or at least a reaction to modernity.

Words are cheap. And “solidarity” across the oceans is pretty much worthless. But I think it is something to at least say that there, but for the grace of God go I, ironically in this particular case. To me a measure of the worth of a society is its ability to tolerate heretics. That is why I sympathize with the ancient Hellenists, and not the waxing homogeneity of Christendom über alles. And that is why I think the world of Islam is today by and large an inferior vessel for human possibility. Not to sound too much a Spenglerian, but I do hope that this flare-up of Islamic violence is simply a reaction to the inevitable liberalism which is being ushered in by the demographic transition and economic growth evident across Bangladeshi society.

 
• Category: Foreign Policy • Tags: Bangladesh 
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200px-IbnWarraqwhyIAmNotMuslim There’s an old joke that people in Alabama can be rest assured that when scholars tote up social statistics there’s always Mississippi to make sure that their state isn’t the last one listed. Sometimes I feel that way when thinking about comparing Bangladesh to Pakistan. Right now it is big news that an atheist blogger has been killed in Bangladesh, presumably by Islamic militants or sympathizers thereof. Naturally people are bringing this to my attention because 1) I was born in Bangladesh 2) I’m an atheist 3) I’m a blogger. But there are some important differences. From what I am to gather this blogger was focused on issues relating to atheism and secularism, and, his core audience was Bangladeshi. I write to a mostly American audience, and religion as a political issue is not a primary focus of mine (as opposed to a scholarly interest). Honestly I am more frightened of dying of a disease than being hacked to death by Islamist radicals if I were to visit Bangladesh, because I’m not that prominent.* Though this is certainly another argument for why I might want to avoid that country. In How The Scots Invented the Modern World the author points out that the last person killed on account of their atheism in the British Isles lived around 1700. Though the killing of Avijit Roy is not quite analogous, because it was a vigilante action, it illustrates the social sentiment broadly in society that blasphemy may be a capital crime in some parts of the world, hundreds of years after this sort of fanaticism abated in the West.

gsi2-chp1-9 Of more interest to me is that there is an atheist movement in public in Bangladesh at all. This is after all a very underdeveloped nation (Pakistan is still more economically developed) which is highly religious. It is also a nation where religious minorities occupy a somewhat precarious position. Nevertheless, against the standard and trajectory of Pakistan Bangladesh is relatively liberal and advanced when it comes to religious liberty from a Western perspective. The chief justice of the Supreme Court of Bangladesh is a Hindu. Unlike Pakistan the Ahmadis receive some official protection. One of the two major political parties, and the one currently in power, has maintained a stronger commitment to secularism in the face of pressure from the religious elements than its socialist analog in Pakistan (though it too has caved to aspects of Islamicization of society since the 1970s).**

The reasons for this difference are multifaceted. It could be as simple as the historical contingency that the United States buttressed the Islamic autocracy of Zia ul-Huq in the 1980s. Though today Pakistan is a byword for Islamic extremism, I tend to be of the opinion that its origins can be understood more as an instance of ‘religious nationalism,’ akin to Revisionist Zionism. The founder of Pakistan had a religious background which would be unacceptable to many Pakistanis today, and his personal piety was minimal. Pakistan initially served as a redoubt in the Indian subcontinent against Hindu numerical dominance, not the catspaw in Sunni radical millenarianism. It was a place where the traditional Muslim elites could take their rightful role as the political leaders, rather than being marginalized as would have been the case in a democratic India. Over time this national identity, of which religion was a part, though never a totality, has become more and more tied in with currents in international Sunni Islamic radicalism (to the obvious detriment of the non-Sunni minorities, including Shia such as the founder of the nation himself).

But this isn’t just a matter of sentiments on high. Rather, the reserves of secularism and tolerance for heterodoxy run deeper in modern Bangladesh than they do in Pakistan. Though >80 percent of both Pakistani and Bangaldeshi Muslims agree that Sharia should be the law of the land, less than half of Bangaldeshis who agree with this proposition believe that those who leave Islam should be subject to the death penalty according to Pew. It is notable that there are people willing to speak the record on video defending the right to Roy expressing his atheism. An English language newspaper in Bangladesh reflects this sentiment. Looking around the web about Pakistani atheism, it seems quite closeted, and columnists who write about it seem to parse their words carefully so as to avoid vigilante attention.

Writing about the modest protests The Guardian notes:

The attacks starkly underline an increasing gulf between secular bloggers and conservative Islamic groups, often covertly connected with Islamist parties. Secularists have urged authorities to ban religion-based politics, while Islamists have pressed for blasphemy laws to prevent criticism of their faith.

It is important to note that despite the groundswell of anger from the usual suspects among Muslims, there is still a strong enough secular liberal intelligentsia in Bangladesh which can speak in favor of someone as religiously marginal as an atheist from a Hindu background. The murder is a tragedy, but the reaction is to some extent heartening, and I hope heralds a future where social conflict can give way to the driving of religion into the private sphere (I think banning religious parties is usually counterproductive, for the record. I’d also oppose banning them on principle even if it was productive).

* Though I checked, and it is interesting that I have more Twitter followers from Bangladesh than Germany, probably on account of my name.

** The Awami League and the People’s Party respectively.

 
• Category: Foreign Policy • Tags: Bangladesh, Religion 
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Credit: Sci Transl Med 3 July 2013: Vol. 5, Issue 192, p. 192ra86, Sci. Transl. Med. DOI: 10.1126/scitranslmed.3006338

Right before I was to sleep a reader sent me an email which pointed to a Nick Wade piece in The New York Times, Gene Sleuths Find How Some Naturally Resist Cholera. It’s about new research in ScienceTranslational Medicine, Natural Selection in a Bangladeshi Population from the Cholera-Endemic Ganges River Delta. The authors use the “composite of multiple signals” (CMS) test to ascertain regions of the genome subject to natural selection (look for long haplotypes, high frequency derived alleles, and alleles with high cross population frequency differences). The results aren’t too surprising, I was born in Bangladesh, and I can attest to the fact that it’s a germaphobe’s nightmare. Rather, it is a secondary and very minor aspect of the paper which frankly draws my ire. First let’s quote Wade’s treatment:

As a necessary preliminary to testing for natural selection, the researchers looked at the racial composition of the Bengali population and found that they are an Indian population with a 9 percent admixture of East Asian genes, probably Chinese. The admixture occurred almost exactly 52 generations ago, according to statistical calculation, or around A.D. 500, assuming 29 years per generation. The Gupta empire in India was in decline at this time, but it is unclear whether the intermarriage with East Asians took place through trade or conquest. “We can now go back to the historians and see what happened then,” Dr. Karlsson said.

But sometimes science gets garbled in transmission. What do they say in the paper? Again, the relevant section:

We estimate that the admixture between Indian and East Asian populations occurred 52 ± 2 generations ago (generation = 29 years)…or around 500 AD, based on the exponential decline of linkage disequilibrium (LD) with distance analyzed using ROLLOFF…This remarkably close-fitted age estimate roughly corresponds to the collapse of the Indian Gupta Empire, the rise of the Chinese Tang dynasty, and the brief unification of Bengal under a single ruler (590 AD to 625 AD). Although alternative histories, such as continuous admixture or multiple admixture events, are possible, the single-event model shows excellent fit to our data, and we found no statistical support for very ancient flow…Using the maximum likelihood–based ancestry estimation software ADMIXTURE (32), we found 9.3 ± 2.6% East Asian ancestry in the BEB….

If you read the rest of the paper you can see where Wade would get the idea that the admixture was “probably Chinese,” but I don’t think it jumps out from the text or the supplements. Perhaps he got this from the first author who is quoted; I have no idea. The population history component of this work is not essential to the understanding of the selection operating via disease, but the problem when this sort of confusion is allowed to stand is that it will become solidified conventional wisdom. I’ve seen this happen before, as throwaway lines have a way of persisting and spreading. Additionally, it also makes geneticists seem superficial when they step outside of their narrow domains of presumed knowledge.

In fact the reality of who these East Asians are in the Bengali ancestral gene pool is clear in the supplements. At K = 5 you see that a Malay-like ancestral component emerges, and all of the East Asian ancestry of the Bengalis is assigned to this. You also have the Han Chinese and Chinese in Singapore data sets split between a Japanese-like and Malay-like component. The Chinese in Singapore is more Malay-like. This is entirely expected, as the Singapore Chinese population is disproportionately from the southwest region of Fujian, with a minority of Hakka (who are reputedly northern transplants to South China), as well as Straits Babba Chinese, who have maternal Malay ancestry. The Han Chinese data set is from the HapMap, with a Beijing sample which is northern biased. In sum, the East Asian ancestry of the modern Bengalis is almost certainly derived from a group with the closest affinities to those in Southeast Asia, not, the Chinese.

I have long suspected this because I have genotypes for two unrelated Bengalis, my parents. I’ve talked about this before. Some preliminary investigation on my part looking at the East Asian segment length did suggest an admixture event ~1,000 years ago, so I can believe the ROLLOFF results. But comparing them to various populations, it’s clear that the East Asian ancestry is Southeast Asian for both of them. Here’s a MDS I generated 15 minutes ago using 133,000 LD pruned SNPs:

The Chamar are a low caste group from Uttar Pradesh (to the north and west of Bengal). You notice that my parents (“RazibFam”) are both shifted toward the Southeast Asian groups. Totally unsurprising. No matter how you analyze the results this jumps out (the second dimension pulled out a few inbred individuals from another Southeast Asian group).

So assuming one admixture event (or a primary one), what’s a good story? Eastern Bengal has always been on the margins of and beyond Aryavarta, the cultural core of the North Indian plain. Magadha, the heart of the Gupta Empire in Bihar, was long a marchland. Like the region around Xian in northwest China Magadha was often the locus of the classical pre-Islamic Indian macro-polities, despite (or perhaps because of?) its liminal relationship to the broader Indo-Aryan culture of Northern India, which was fixed upon the Upper Gangetic plain. As Magadha collapsed, and Bengal rose under dynasties such as the Pala later in the first millennium the frontier of Indo-Aryan society rapidly expanded outward and eastward. But I doubt eastern Bengal was empty. It is quite possible there were slash & burn agriculturalists who had arrived at some previous time from Southeast Asia. And it is these who I believe were absorbed into Bengali society in toto.

(Republished from Discover/GNXP by permission of author or representative)
 
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Recently I was tipped off to the appearance of a new paper, Genome-Wide Association Study Identifies Chromosome 10q24.32 Variants Associated with Arsenic Metabolism and Toxicity Phenotypes in Bangladesh. This is the section which caught my eye: “Using data on urinary arsenic metabolite concentrations and approximately 300,000 genome-wide single nucleotide polymorphisms (SNPs) for 1,313 arsenic-exposed Bangladeshi individuals.” 300 K SNPs with 1,313 Bangladeshi individuals is a lot! I’m interested in this data set because of the 200+ participants in the Harappa Ancestry Project my parents remain the “unadmixed” South Asians with the highest fraction of East Asian ancestry (10-15 percent). Within South Asia aside from those groups with clear East Asian affinities only peoples of Munda background have the same levels. This data set could answer a lot of questions as to the typicality of my parents (literally within a few hours in terms of data exploration). But this is all you get in the supplements:

 


Zack Ajmal has already sent off an email asking about this data set, so hopefully the results will be positive.

This is a medical genetics study, so all they wanted to confirm is that there wasn’t population stratification due to inbreeding. They confirmed that. It is fine if they don’t want to explore further questions in relation to ancestry, but it would be really depressing if the data set can never see the light of day for those who are interested in asking other questions.

(Republished from Discover/GNXP by permission of author or representative)
 
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mtDNA haplogroup G1a2

The pith: In this post I examine the most recent results from 23andMe for my family in the context of familial and regional (Bengal) history. I also use these results to offer up a framework for the ethnognesis of the eastern Bengali people within the last 1,000 years, and their relationship to other South Asian and Southeast Asian populations.

Since I received my 23andMe results last May I’ve been blogging about it a fair amount. In a recent post I inferred that perhaps I had a recent ancestor who was an ethnic Burman or some related group. My reasoning was that this explained a pattern of elevated matches on chromosomal segments with populations from southwest China in the HGDP data set. But now we have more than my genome to go on. This week I got the first V3 chip results from a sibling. And finally, yesterday the results from my parents came in. One thing that I immediately found interesting was my father’s mtDNA haplogroup assignment, G1a2. This came from his maternal grandmother, and as you can see it has a distribution which is mostly outside of South Asia. In case you care, I asked my father her background, and like my patrilineage she was a “Khan,” though an unrelated one (“Khan” is just an honorific). I received these results before the total genome assessment, and so initially assumed this confirmed my hunch that my father had some unknown recent ancestry of “eastern” provenance. But it turns out my hunch is probably wrong. In fact, my parents have about the same “eastern” proportion, with my mother slightly more! My expectation was that perhaps my mother would be around 25-30% “Asian,” and my father above 50%. The reality turns out that my father is 38%, and my mother 40%.


Image credit: f_mafra

Below are the “Ancestry Paintings” generated by 23andMe for my family (so far). What you see are the 22 non-sex chromosomes, which have two copies each, and assignments to “Asian,” “European,” and “African,” ancestry groups. The reference populations to generate these assignments come from the HapMap, the northern European sample of white Americans from Utah, Chinese from Beijing, Japanese from Tokyo, and ethnic Yoruba from Nigeria. What the assignment to one of these classes denotes is that that region of the genome is closest to that category in identity. It does not imply that your recent ancestry is European or Asian (African is probably a different matter, but there are many complaints about the results for African Americans and East Africans in the 23andMe forums). This caveat is especially important for South Asians, because we generally find that we’re ~75% European and ~25% Asian. All that means is that though most of our genetic affinity is with Europeans, a smaller fraction seems to resemble Asians more. Via “gene sharing” on 23andMe I can see that the Asian fraction varies from ~35% in South India and Sri Lanka, to ~10% in Pakistan and Punjab. This is not because South Indians have more East Asian ancestry than Punjabis. Rather, to a great extent the South Asian genome can be decomposed into two ancestral elements, one with a distant, but closer, affinity to populations of eastern Eurasia, and one with a close affinity to populations of western Eurasia. What some have termed “Ancient South Indians” (ASI) and “Ancient North Indians” (ANI). ASI ancestry, which is probably just a touch under 50% in South Asians overall, seems to shake out then as somewhat more Asian than European.* The fraction of ASI increases as one moves south and east in South Asia (and as one moves down the caste status ladder).


[zenphotopress album=249 sort=sorder_order number=4]


First, I want to note that I’ll be using abbreviations for my family members now and then (this applies to future posts). My father will be RF, my mother will be RM, and my siblings will be RS, with a number to denote which sibling. So currently we have RS1. As you can see in a gestalt sense we resemble each other a great deal as a family. We’re about 40% Asian, and 60% European. The extent of fragmentation indicates that we’re not that recent of an admixture; otherwise, the Asian and European fragments would cluster on one strand or the other. Some have suggested that my mother does exhibit less fragmentation. A hypothesis for why this may be is that her maternal grandfather was reputedly from a family of Middle Eastern origin who had resettled in South Asia, first in Delhi, and later in southeast Bengal (specifically, the district of Noakhali). Since he presumably would hardly have had any Asian ancestry according to 23andMe’s algorithm the homologs inherited from him would be overwhelmingly European, with only one generation of recombination intervening.

To assess probabilities of the plausibility of various hypotheses to explain the pattern of the results you need all the non-genomic information. Above is a map of British India. I’ve pointed to the region of Bengal from which my family comes. Of my great-grandparents 7 out of 8 were born in Comilla (which is actually a greater expanse to the southeast of Dhaka than the current Bangladeshi administrative division). 1 grandparent was born in Noakhali, which is just to the southeast of Comilla. 4 out of 8 great-grandparents were born within 5 miles of the town of Chandpur (RF’s grandparents). 3 out of 4 great-grandparents were born within 5 miles of the village of Homna (RM’s grandparents). These two locations are about 30 miles from each other as the crow flies, though transport between them would have been by water in an earlier era (Homna is on the Meghna river, which is actually a more substantial body of water than the Ganges by the time the latter reaches Bangaldesh). This region is bounded on the west by the Padma river, which narrows at Chandpur to about 2 miles in width (average depth ~1,000 feet). To the east is the Indian state of Tripura. This is a relatively porous border, defined on the map, not imposed by geography. You can see that in some regions the Bangaldesh-India border here in the east actually bisects rice paddies.


Tripuri children

Today Tripura state is majority ethnic Bengali due to mass migration of Hindus from what was East Bengal during the 20th century (and later East Pakistan, and now Bangladesh). But its indigenous people are the Tripuri, a tribe whose native language is clearly Tibeto-Burman, and physical type points to their connection with populations to the north and east. At the same time, ~90% of the Tripuri are Hindus, and during the period of Islamic rule in South Asia the rajahs of Tripura styled themselves defenders of Hindu civilization (just as the Tibeto-Burman Ahoms of Assam did). As such, linguistically and genetically the native people of Tripura exhibit a sharp contrast to the Indo-Aryan peoples of the Gangetic Plain, of whom the Bengalis are the easternmost representatives along with the Assamese. But, they have also long been part of the South Asian cultural scene, and can not longer be viewed as purely intrusive (their oral history indicates that they arrived before the Muslims, for one).

Finally, in regards to the detailed backgrounds of my 8 great-grandparents, 2 were of the Khan class. 1 was from a family of Hindu Thakurs who were recently converted to Islam. Another was of the family name Sarkar. 1 was likely from a family of Middle Eastern transplants to South Asia, at least in part. The 4 remaining great-grandparents were Bengali Muslims, with no particular background information beyond that known by my parents.

I gave you all this because genetic variation is strongly conditioned upon geographical and cultural parameters. Water barriers seem to have been particular efficacious in the pre-modern period dividing people culturally and genetically (though ironically water was also a precondition for any bulk trade). Language is also another major parameter of difference. And finally, there is religion. In the last section I would not be surprised if 300 years ago the majority of my ancestors in that generation were Hindus; there is some fluidity in this obviously. I provide the data on radius of place of birth because we know from European results that even villages exhibit genetic clustering. This is mitigated in my family because my father has a diverse background among his grandparents as far as community goes, while my mother has a grandparent who was from a different district, and to a great extent a different ethnic group in biological terms.

When I initially saw that I was ~40% Asian I was little taken aback by the high proportion (remember, the average South Asian is about 25% Asian), but there were two parsimonious explanations, a) I had a lot of ASI, b) I had ancestry which did not seem South Asian as such, but was genuinely from East Asia. To ascertain whether it was the former I began proactively gene sharing with a wide range of South Asians on 23andMe. After dozens of individuals it became clear that I was outside of the normal interval of variation. I was more Asian than individuals from South India or Sri Lanka. Additionally, even these individuals tended to be genetically closest to Central South/Asians in the HGDP data set. I was closest to East Asians. Also, on the two dimensional PCA projected onto Central South/Asians I was definitely outside of the cluster of all the other South Asians. Finally, I did find someone who broke the magic 35% barrier of Asian…and that individual was a Bangladeshi, at 38%. And, like me, he was closer to East Asians on the basic “Global Similarity” match. He also carried a Y chromosomal lineage which was rare in South Asia and common among the Hmong. Finally, when Dienekes started his Dodecad Ancestry Project it was clear that about ~15% of my ancestry clustered with an element which was not South Asian, but East Asian. If one removes this fraction, I would be about 70% European and 30% Asian, absolutely within the normal range for someone with ancestry to the east or south of the subcontinent.

If you’ve read up to this point, you may be wondering how it is that my father is 38% Asian and my mother is 40% Asian, and I’m 43% Asian. After all, shouldn’t I be an average between the two? Actually, on the PCA scatter plot I am (along with my sibling) exactly between my parents (you can’t see the offspring because the flags are just too large). So why the difference? First, remember that the PCA is projecting you onto a two dimensional axis where the x and y represent the two biggest components of variance in the data set. In other words, it’s yanking out the subset of genetic variance which really stands out in terms of between population difference. This is how an individual who is a first generation Eurasian can be so far from their parents on this plot, but still exhibit a great deal of identity by state in terms of total genome; there’s a lot of variation that the two dimensional plot does not capture (e.g., private variants to family lineages). The Ancestry Painting estimates are different; they’re looking across the whole genome and making assessments for each region as to its genetic affinity between the three reference populations. So to repeat, you have over 50 reference populations vs. 3, and, you have a small proportion of the total genetic variation, vs. the whole genome. Both methods are reporting real and valid results, but they’re somewhat different.

So there are two very simple and methodological explanations for the discrepancy above which I can think of. I’m on V2, while my parents and sibling are on V3. I know this has made a difference in other measurements. Additionally, there’s clearly some “noise” within this algorithm, resulting in people with trace African or Asian ancestry which isn’t real, even if you take into account the kludgey nature of the reference populations. But let’s take the results at face value. With the ancestry painting, recall how the European and Asian components were chunky across the genome? Both of my parents received half their genomes from their parents. My own chromosomes are a mosaic of those of my grandparents. Some of the original linkage between genomic regions because of their physical location on the same strand have been broke apart by recombination in the two generations downstream from my grandparents. Concretely, two instances of meiosis which produced sex cells. Therefore, some of the associations of alleles present in my grandparents have been transformed within me. But even without recombination, it is clear that one homologous chromosome could be more European or Asian than the total genome average. Because only one of these is passed to any given offspring, there is going to be variance from sibling to sibling. Genetics is not a pure blending process. That may be why I am 43% Asian while RS1 is 40% Asian. We’re both sampling from our parents genes, and there’s going be variance in that process (on the chromosomal level you have 22 autosomal draws from each parent where each draw has two outcomes).

An interesting implication of this is that the grandchildren of a multiracial couple will exhibit variance in their ancestral quanta from major racial groups. This is one reason why it is a fallacy to presume that intermarriage will result in the washing away of biological diversity. And processes such as assortative mating could even presumably extract out “pure” individuals from an originally admixed random-mating population.

With all that said, I now believe that with an N = 3 from eastern Bengal that I am not an exception with recent Southeast Asian ancestry, but rather eastern Bengal is part of the gene frequency cline between South Asia and Southeast Asia, and as such has a substantial fraction of eastern ancestry. Zack has my parents’ data, so once the results come back from the first runs of HAP I believe that he will see the same pattern of substantial non-South Asian ancestry in them that Dienekes found in me. The cline here is still sharp. The average Bangladeshi is probably interchangeable with just 10-20% with the average Burmese when it comes to proportions in inference of ancestral quanta algorithms. (remember that the Burmese probably have a small South Asian component too). In contrast, the average Bangladeshi probably can be interchangeable at 80-90% with a resident of Bihar (the closest match in total SNP comparison in 23andMe that I’m sharing with is a Bihar, not the two other ethnic Bengalis). This is clearly a function of geography, the north-south ranges in Burma seal it off from South Asia. In contrast, there are open plains from northern Bangladesh to Bihar. In some ways Burma has more cultural affinity and connection with peninsular South Asia because of the ease of maritime travel. The prevalence of Theravada Buddhism in Burma is a testament to the association of the lower Irrawaddy region with Sri Lanka.


Back to Bangladesh. One aspect of the Indian subcontinent in terms of religious demography is that the heart of Indo-Islam, the Delhi area, never had a Muslim majority. Rather, Muslims were a majority along the northwestern and northeastern fringe (along with a few other districts, such as northern Kerala). The predominance of Islam on the northwest isn’t that surprising, as that region borders upon the Dar-al-Islam proper. But what about Bengal? In the late 19th century the British were apparently surprised that in the united Bengal (which includes roughly the modern state of West Bengal in India, and Bangladesh) had a Muslim majority. Because of differential birth rates and conversion (this second includes sections of my family as I note above) about 2 out of 3 ethnic Bengalis alive today are Muslim, with the balance being Hindu. Bangladesh is estimated to be 90% Muslim, while West Bengal is 25% Muslim. Even today after generations of Hindu outmigration one pattern within Bangladesh is the relative concentration of Hindus to the west and north (also, Hindus in Bangladesh tend to be urban). The “buckle” of the “Koran belt” in Bangladesh is actually the district of Noakhali, on the southeast fringe of Bengal. My mother’s maternal grandfather, who came from a lineage of pirs who had originally settled in the Muslim heartland in Delhi, was from Noakhali. It is apparently said that in Noakhali even the Hindus know proper Islamic forms!**

An explanation for this pattern is that the religious influence and power of Hindu elites declined as a direct function of distance from the regions of West Bengal, which were closer to the core Aryavarata, and had traditionally been the locus of power of Hindu dynasties before the rise of Islam. Additionally, Bengal was the last region of the mainland subcontinent with a robust Buddhist society during the flowering of the Pala Empire around the year 1000. It is therefore suggested that many Bengali Muslims were converted directly from Buddhism, not Hinduism (there remains even today a small minority of ethnic Bengali Buddhists, who carry the surname “Baura.” This is in distinction to the descendants of Tibeto-Burman people who now speak Bengali, but retain a tribal identity and Theravada Buddhist religion). Also, it may be that eastern Bengal was populated mostly by animist tribes before the arrival of Muslims, and just as European colonial powers were more successful in Asia at spreading their religion among marginalized people (e.g., tribal peoples in northeast India and Southeast Asia are often Christian), so Islam found purchase among those outside of the Hindu caste system.

These models are broadly persuasive to me. But, I still am suspicious that there was such a strong disjunction in the depth of Hindu institutions in western vs. eastern Bengal; after all, the kings of Tripura to the east were Hindu when Islam was new in South Asia. If being tribal and marginal to the core Hindu civilization was one of the grounds for susceptibility to Islam it is peculiar that it is precisely many tribal people in modern Bangladesh who are not Muslim. Indeed, the Tibeto-Burman populations nearer to Indian groups in eastern South Asia are Hindu or Buddhist, not Muslim (those further in the hinterlands were not integrated into any South Asian religion, but converted to Christianity by Western missionaries within the last century).

Instead, I find the model espoused in The Rise of Islam and the Bengal Frontier, 1204-1760 broadly plausible as a complement, or even substitute, to the above hypotheses. Additionally, it has the utility of making sense of the genetic data which I have presented here so far. The author argues that eastern Bengal, most of Bangladesh, was very lightly populated before the conquest of Bengal by Muslims in the 13th century. During the modern era the western region of Bengal, in India, has tended to have issues with the moribund nature of many of the water courses. But one thousand years ago this region was more active in terms of sedimentation, while eastern Bengal was a wilderness. Over the centuries there has been a shift of large rivers to the east, opening up that area to cultivation because of improved transport. Additionally, the arrival of Muslims also resulted in the spread of new techniques of land clearing and settlement. The rough model is that eastern Bengal is in fact a relatively newly settled territory in terms of its current demographic density. As the clearance and settlement operations were performed by Muslim elites, many of the peasants who settled these lands were either Muslim, or more likely, adopted the religion of their landlords. Because of the virgin nature of the territory these original settlers entered into a phase of massive demographic expansion, to the point where eastern Bengal (Bangladesh) is now today twice as populous as western Bengal (West Bengal). The key here is that there need not be a massive conversion of the enormous masses of marginal animist, Hindu or Buddhist peasants. Rather, all one needs is a modest number of converted Bengali peasants to enter into exponential population growth until the land is “filled.” (interestingly, one sees similar patterns between descendant populations in both the USA and among Koreans. The religions in the “core” homelands are very different in constitution from the Diaspora)

I find this persuasive for two major reasons. First, Peter Bellwood’s First Farmers documents the difficulties of populations which have not been engaged in intensive farming to switch to that modality. At least back to the Mughal period Bengal was a densely settled land from which one could extract massive rents simply due to aggregate productivity. Today a united Bengal would have a population of 240 million, making it the fourth most populous nation in the world, below the USA, and just above Indonesia. In hindsight I find it less likely that the peasants of eastern Bengal descend from tribal peoples who had been practicing extensive agriculture, but were introduced to new techniques, than that western populations already habituated to the grinding expectations of intensive farming colonized the “empty” lands (in fact, Bengali peasants migrate to Assam in part because of the perception of land surplus there, even though Assam has 30 million inhabitants). But this initial phase of colonization would entail relatively few peasants, and probably exhibit some male bias. Therefore, this can to explain a substantial fraction of the eastern ancestry among Bangladeshis, as in the first generations the Bengali peasants did assimilate the native tribal peoples of the region, whether it to be the Munda Santhals or Tibeto-Burman relatives of the Tripura. With the massive numbers of ethnic Bengalis in comparison to Tibeto-Burman groups it seems one would need a great deal of gene flow in any model which posited that exchange between these two groups over long periods of time explain the high fractions that one finds of non-South Asian ancestry. In all of India there are only 10 million speakers of Tibeto-Burman languages, vs. the 240 million speakers of Bengali alone in the Indian subcontinent.

Where does this leave us? From what I gather you’ll probably not make it into the first round of results for HAP, but if you have 23andMe results and haven’t it sent it to Zack, and want to learn more about the historical genetics of the Indian subcontinent, you can still get involved! With my parents Zack now has an N = 2 of Bengalis. It would be nice to get more. We still need samples from North-Central India. The number of Punjabis is in the 5-10 range, Tamils is around 5. Enough to make inferences, but certainly not robust enough to bet the house on. In the near future I’ll get results from my other siblings, and I’ve decided to “upgrade” to the V3 chip. Once that comes in I’ll phase some of the results, and probably start comparing myself to my siblings, “phase” the results, etc.

* Native Americans, descendants of pre-Columbian Americans, have the inverted results from South Asians, mostly Asian with a European minority. This is not just due to recent European admixture. Rather, though Amerindians have affinities to East Asians, the two groups have been distinct for at least 10,000 years, and probably considerably longer.

** Also, some have stated that the people of Noakhali are sly and cunning, adept at following the letter of the law, but not the spirit. I only know this because when I was young one of my father’s friends, also from Bangladesh, complained that a mutual acquaintance from Noakhali who made much of his piety (he put his wife in purdah when she arrived from Bangladesh) requested that someone else purchase a pornographic magazine for him. His reasoning was that he did not want to be seen purchasing the magazine. It was a sin to purchase such an item for a good Muslim. Later my father and his friend (who was from northern Bangladesh for what it’s worth) commiserated that such was the way of the people of Noakhali, amongst whom you have to have your wits about you lest they exploit some angle for their own self-interest. The pious-porn-non-purchaser was notorious for being a non or late payer of rent when he was a lodger with other Bangladeshis, always emphasizing his religious piety as surety of final payment of the debt. He also eventually finagled a loophole in the immigration law of the time, obtaining green card with relative ease and no necessity of sponsorship. The proper connotation of how people from Noakhali are is probably captured by the American English word slick.

(Republished from Discover/GNXP by permission of author or representative)
 
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Razib Khan
About Razib Khan

"I have degrees in biology and biochemistry, a passion for genetics, history, and philosophy, and shrimp is my favorite food. If you want to know more, see the links at http://www.razib.com"