The origins of caste

I am not a scientist, and this is not a science blog. But the just-published study in Nature may have interesting implications for some important legal and political debates around caste. India, the study claims, has been under-represented in ‘genome-wide surveys of human variations’, so this is apparently one of the first of its kind. Before we look at its implications, here is a summary of the results:
The researchers showed that most Indian populations are genetic admixtures of two ancient, genetically divergent groups, which each contributed around 40-60% of the DNA to most present-day populations. One ancestral lineage — which is genetically similar to Middle Eastern, Central Asian and European populations — was higher in upper-caste individuals and speakers of Indo-European languages such as Hindi, the researchers found. The other lineage was not close to any group outside the subcontinent, and was most common in people indigenous to the Andaman Islands, a remote archipelago in the Bay of Bengal.

The researchers also found that Indian populations were much more highly subdivided than European populations. But whereas European ancestry is mostly carved up by geography, Indian segregation was driven largely by caste. “There are populations that have lived in the same town and same village for thousands of years without exchanging genes,” says Reich.
An important biomedical implication of the study is that ‘there will be an excess of recessive diseases in India’. But socially, this study challenges the following theses on the origins and nature of the caste system in India:
1. Caste is a modern, colonial invention: This genetic evidence refutes the claim that the Indian caste structure was a modern invention of British colonialism, the authors say. “This idea that caste is thousands of years old is a big deal,” says Nicole Boivin, an archaeologist who studies South Asian prehistory at the University of Oxford, UK. “To say that endogamy goes back so far, and that genetics shows it, is going to be controversial to many anthropologists.”2. Indigenous origins of the ‘Indo-Aryans’:The theory, especially popular with some RSS ideologues like Golwalkar, that Indo-Aryans originated in India and did not come from elsewhere has become even more untenable. Assuming that the RSS’s ‘Indo-Aryans’ are the same as what the study calls ‘Ancestral North Indians’, their Middle-Eastern/Central-Asian/European origins may be inferred from this finding:…the ‘Ancestral North Indians’ (ANI), is genetically close to Middle Easterners, Central Asians, and Europeans, whereas the other, the ‘Ancestral South Indians’ (ASI), is as distinct from ANI and East Asians as they are from each other. By introducing methods that can estimate ancestry without accurate ancestral populations, we show that ANI ancestry ranges from 39–71% in most Indian groups, and is higher in traditionally upper caste and Indo-European speakers.Of course, this finding does not make the ANI’s any less ‘Indian’. It only raises problems for those who sustain the ‘pitribhumi – punyabhumi’ thesis of exclusionary nationalism by relying on the indigenous origin theory.
3. Is caste race?Why does it matter? Both caste and race are human constructs, but because of their association with endogamy, may have implications for human genetic make-up. Both have been used to exclude and discriminate. Does it matter what we call such exclusion?For lawyers, it does. International law and legal institutions have developed to deal with racism. Caste, seen as a one-region problem, has not received similar attention. The issue became controversial in 2001, when the International Conference on Racism in Durban took place. Many dalit groups insisted that casteism was a form of racism; while the government, in keeping with its approach to all international monitoring of human rights, strongly refuted the claim. If caste was indeed race, India would be pulled up by the international institutions that deal with racism. Much academic time has been spent on the issue since the conference. Under the International Convention on Racism, descent and ethnic origin are constituent elements of ‘race’ One wonders what the implications of the research will be on this debate.

Written by
Tarunabh Khaitan
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    Hi Tarunabh,

    Read your post with great interest.

    The above link gives a series of "scientific" studies that try to establish that the aryan invasion theory is false.

    My knowledge of the whole area is as murky as anyone else's – this murkiness makes me extremely skeptical about any simplistic claims about the origins of "Indian" people –

    Skpetical both towards RSS inspired theories that Indians are the source of Europeans and skpetical towards imperial/leftist theories of thousands of years of domination by cattle grazing brahmins of an indigenous population.

    But I think in the interests of fariness – one must point out that there seems to be respectable 'scientific' opinion that goes against the aryan invasion/migration theory.

    Bad science can come from both sides – left and right


  • thanks for your comment. i think this study is interesting because it does not appear to have been driven by any obvious political agenda, and is published by one of the most respected scientific journals in the world. of course, this doesn't mean it cannot be challenged. but the problem is at a more basic level – why do so many social and political debates revolve around historical and scientific facts? even if races and castes were genetically distinguishable, why should it make any difference to how we order our societies? Why is place of historical origin so important to defining citizenship rights?

    the reason i did not take a position on the 'is caste race' question is because i am not sure what role, if any, scientific (rather than cultural) facts play (or should play) in defining 'race'. It would be much simpler if we could just agreed that caste and race, both accidents of birth, are unfair bases to distribute rights and resources.

    I personally find its biomedical implication concerning diseased genes passed on by endogamy most interesting.

  • Science cannot give clear cut answers to many questions like origin of caste etc.In fact even defining caste is not so easy.
    What does caste mean in terms
    of genes and genetic uniformity/
    diversity. In a country where there is rich diversity (billion plus population and thousands of caste and hundreds of languages)
    seeking simple answers in the context of present controversies
    wont take us far.
    In this study the sample size is very small. There is every danger of invoking science with limited data and hypotheses that are yet to be confirmed by other studies to claim as if science has
    found answers.

  • Hi Tarunabh,

    I read the article on the Nature's website as well as the original paper. All its says that Indians appear to be a genetic blend of caucasian/central asian strain and a dravidian strain; neither is a fundamentally accessible anywhere any more, except for the dravidian strain in the Andamans. The Single Nucleotide Polymorphisms – a genetic signature at the single nucleotide level, not at the gene level – used in the analysis is sensitive but not the most informative.

    As the comment by Aravinda Chakravarti points out that mixtures of the strains has not been temporally placed – this, in my opinion, is the interesting aspect. Much of the sociological and the anthropological research already suggests that this mix has been happening during the course of the millenia or more and, I suspect, the genetic studies will confirm that.

    I feel that some of the comments highlighted in the article make the the findings of the paper appear contrary to the informed opinions about Indian ancestry, which they are not. Though it will twist the tails of the RSS-wallahs …

    Coming to your issue of discrimination – it still is important to emphasize/remember that there is no scientific basis for caste-based discrimination, lest someone imagines arguments (pseudo-science in the garb of science) to the contrary. In this day and age, it is self-evident that caste, gender, sexual orientation should not be the basis for negative-discrimination. Law can proscribe such discriminations; many laws in India do so. But it is not clear from your post, how much more of this should be dictated by law. One of your suggestion is that India sign onto the optional protocol of ICCPR and CEDAW; well, if you can ask India to be its signatory, surely you can ask India to release reports using the same prescribed standards. For the legitimacy and future of the Indian republic, it is important that its institutions perform credibly. While it is important to imbibe the thinking of the world outside, it is important to ensure that it is the institutions within that deliver justice.


  • It seems to me that ANI and ASI are mathematical constructions from Principal Component Analysis. They say in Supplement 1:
    "We warn that 'models' in population genetics should be treated with caution. Although they provide an important framework for testing historical hypotheses, they are oversimplifications. For example, the true ancestral populations of India were probably not homogeneous as we assume in our model, but instead were probably formed by clusters of related groups that mixed at different times. However, modelling them as homogeneous fits the data and seems to capture meaningful features of history."