Genetic evidence for the spread of Indo-Aryan languages

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My own investigations on the Bronze Age and Early Iron Age peoples of Eastern Central Asia (ECA) began essentially as a genetics cum linguistics project back in the early 90s.  That was not long after the extraction of mtDNA (mitochondrial DNA) from ancient human tissues and its amplification by means of PCR (polymerase chain reaction) became possible.

By the mid-90s I had grown somewhat disenchanted with ancient DNA (aDNA) studies because the data were insufficient to determine the origins and affiliations of various early groups with satisfactory precision, neither spatially nor temporally.  Around the same time, I began to realize that other types of materials, such as textiles and metals, provided powerful diagnostic evidence.

By the late 90s, combining findings from all of these fields and others, I was willing to advance the hypothesis that some of the mummies of ECA, especially the earliest ones dating to around 1800 BC, may have spoken a pre-proto-form of Tocharian when they were alive (some people think it's funny or scary to imagine that mummies once could speak).  This hypothesis was presented at an international conference held at the University of Pennsylvania in April, 1996, which was attended by more than a hundred archeologists, linguists, geneticists, physical anthropologists, textile specialists, metallurgists, geographers, climatologists, historians, mythologists, and ethnologists — including more than half a dozen of the world's most distinguished Tocharianists.  It was most decidedly a multidisciplinary conference before it became fashionable to call academic endeavors by such terms (see " Xdisciplinary" [6/14/17]).  The papers from the conference were collected in this publication:

Victor H. Mair, The Bronze Age and Early Iron Age Peoples of Eastern Central Asia (Washington, D.C.: Institute for the Study of Man Inc. in collaboration with the University of Pennsylvania Museum Publications, 1998).  2 vols.

See also:

J. P. Mallory and Victor H. Mair, The Tarim Mummies: Ancient China and the Mystery of the Earliest Peoples from the West. (2000). Thames & Hudson. London.

"Early Indo-Europeans in Xinjiang" (11/19/08)

It is only very recently, within the last ten years or so, that Y-chromosome analysis has been brought into play for the study of ancient DNA.  See Toomas Kivisild, "The study of human Y chromosome variation through ancient DNA", Human Genetics, 2017; 136(5): 529–546; published online 2017 Mar 4. doi:  10.1007/s00439-017-1773-z.*  Since only males carry the Y-chromosome, this has made it possible to trace the patriline of individuals.  This, coupled with the massive accumulation and detailed analysis of modern DNA with increasing sophistication and the rise of the interdisciplinary (!) field referred to as genomics, has made studies on the genetics of premodern people, including their origins, migrations, and affinities, far more exacting than it was during the 90s when I did the bulk of my investigations on the early inhabitants of the Tarim Basin.

Now it is possible to draw on the results of genetics research to frame and more reliably solve questions about the development of languages from their homeland to the far-flung places where they subsequently came to be spoken.  One such inquiry is described in this article:

Tony Joseph, "How genetics is settling the Aryan migration debate", The Hindu (6/16/17).

It is significant that this substantial article appeared in The Hindu, since there is a strong bias against such conclusions among Indian nationalists (see "Indigenous Aryans").  It begins thus:

New DNA evidence is solving the most fought-over question in Indian history. And you will be surprised at how sure-footed the answer is, writes Tony Joseph

The thorniest, most fought-over question in Indian history is slowly but surely getting answered: did Indo-European language speakers, who called themselves Aryans, stream into India sometime around 2,000 BC – 1,500 BC when the Indus Valley civilisation came to an end, bringing with them Sanskrit and a distinctive set of cultural practices? Genetic research based on an avalanche of new DNA evidence is making scientists around the world converge on an unambiguous answer: yes, they did.

Joseph's paper is informed, sensitive, balanced, and nuanced.  This is responsible science journalism.

The scientific paper itself, “A Genetic Chronology for the Indian Subcontinent Points to Heavily Sex-biased Dispersals” by Marina Silva, Marisa Oliveira, Daniel Vieira, Andreia Brandão, Teresa Rito, Joana B. Pereira, Ross M. Fraser, Bob Hudson, Francesca Gandini, Ceiridwen Edwards, Maria Pala, John Koch, James F. Wilson, Luísa Pereira, Martin B. Richards, and Pedro Soares, was published in BMC Evolutionary Biology (3/23/17) ( DOI: 10.1186/s12862-017-0936-9).

I'm skeptical of many of the claims put forward by geneticists concerning origins and dispersals, not just about humans, but also about horses, dogs, cats, plants, and so forth.  This study, however, is both cautious and solid.  Moreover, it fits well with the archeological evidence (more below).

Here are two key paragraphs from the scientific paper (numbers in square brackets are to accessible references):

Although some have argued for co-dispersal of the Indo-Aryan languages with the earliest Neolithic from the Fertile Crescent [88, 89], others have argued that, if any language family dispersed with the Neolithic into South Asia, it was more likely to have been the Dravidian family now spoken across much of central and southern India [12]. Moreover, despite a largely imported suite of Near Eastern domesticates, there was also an indigenous component at Mehrgarh, including zebu cattle [85, 86, 90]. The more widely accepted “Steppe hypothesis” [91, 92] for the origins of Indo-European has recently received powerful support from aDNA evidence. Genome-wide, Y-chromosome and mtDNA analyses all suggest Late Neolithic dispersals into Europe, potentially originating amongst Indo-European-speaking Yamnaya pastoralists that arose in the Pontic-Caspian Steppe by ~5 ka, with expansions east and later south into Central Asia in the Bronze Age [53, 76, 93, 94, 95]. Given the difficulties with deriving the European Corded Ware directly from the Yamnaya [96], a plausible alternative (yet to be directly tested with genetic evidence) is an earlier Steppe origin amongst Copper Age Khavlyn, Srednij Stog and Skelya pastoralists, ~7-5.5 ka, with an infiltration of southeast European Chalcolithic Tripolye communities ~6.4 ka, giving rise to both the Corded Ware and Yamnaya when it broke up ~5.4 ka [12].

An influx of such migrants into South Asia would likely have contributed to the CHG component in the GW [VHM:  genome-wide] analysis found across the Subcontinent, as this is seen at a high rate amongst samples from the putative Yamnaya source pool and descendant Central Asian Bronze Age groups. Archaeological evidence suggests that Middle Bronze Age Andronovo descendants of the Early Bronze Age horse-based, pastoralist and chariot-using Sintashta culture, located in the grasslands and river valleys to the east of the Southern Ural Mountains and likely speaking a proto-Indo-Iranian language, probably expanded east and south into Central Asia by ~3.8 ka. Andronovo groups, and potentially Sintashta groups before them, are thought to have infiltrated and dominated the soma-using Bactrian Margiana Archaeological Complex (BMAC) in Turkmenistan/northern Afghanistan by 3.5 ka and possibly as early as 4 ka. The BMAC came into contact with the Indus Valley civilisation in Baluchistan from ~4 ka onwards, around the beginning of the Indus Valley decline, with pastoralist dominated groups dispersing further into South Asia by ~3.5 ka, as well as westwards across northern Iran into Syria (which came under the sway of the Indo-Iranian-speaking Mitanni) and Anatolia [12, 95, 97, 98].

The spread of R1a into South Asia had earlier been securely documented in Peter A. Underhill, et al., "The phylogenetic and geographic structure of Y-chromosome haplogroup R1a", European Journal of Human Genetics (2015) 23, 124–131; doi:10.1038/ejhg.2014.50; published online 26 March 2014.

The precise coalescence of R1a within South Asia was identified in Monika Karmin, et al., "A recent bottleneck of Y chromosome diversity coincides with a global change in culture", Genome Research (2015);

This kind of male migration theory is proposed with arguments based on archeological evidence in the last pages of H.-P. Francfort, “La civilisation de l'Oxus et les Indo-Iraniens et Indo-Aryens”, in: Aryas, Aryens et Iraniens en Asie Centrale (Collège de France. Publications de l'Institut de Civilisation Indienne, vol. 72), G. Fussman, J. Kellens, H.-P. Francfort, et X. Tremblay (eds.) (Paris:  Diffusion de Boccard, 2005) pp. 253-328.  The complete paper is on academia website.

Michael Witzel has favored this, the (Indo-)Aryan Migration view, on linguistic and textual grounds since at least 1995 and was constantly criticized for saying so. See his papers of 1995, 2001:

"Autochthonous Aryans? The Evidence from Old Indian and Iranian Texts."  EJVS (May 2001) pdf.

"Early Indian History: Linguistic and Textual Parameters."  In: Language, Material Culture and Ethnicity: The Indo-Aryans of Ancient South Asia. Ed. G. Erdosy (Berlin/New York: de Gruyter 1995), 85-125; —  Rgvedic history: poets, chieftains and politics, loc. cit. 307-352 combined pdf (uncorrected).

and the substrate paper of 1999:

"Early Sources for South Asian Substrate Languages." Mother Tongue (1999, extra number) pdf

Some relevant Language Log posts:

"Dating Indo-European" (12/10/03)

"The Linguistic Diversity of Aboriginal Europe" (1/6/09)

"Horse and wheel in the early history of Indo-European" (1/10/09)

"More on IE wheels and horses " (1/10/09)

"Inheritance versus lexical borrowing: a case with decisive sound-change evidence" (1/13/09)

"The place and time of Proto-Indo-European: Another round" (8/24/12)

"Irish DNA and Indo-European origins" (12/31/15)

*For those who are interested in the development of aDNA Y-chromosome studies beginning in the 2000s, I have some additional documentation and several relevant papers that I can send to you.

[Thanks to Richard Villems, Toomas Kivisild, and Peter Underhill]


  1. Db said,

    June 22, 2017 @ 10:31 pm

    Re: The Hindu and the Indian nationalist

    The Hindu started as a nationalist newspaper during British occupation. However, the current lot of hindutva nationalists who reject the idea of Aryan migration origin of Vedic civilization, probably do not consider The Hindu to be sympathetic to their position.

  2. David Marjanović said,

    June 23, 2017 @ 4:09 am

    Awesome. :-)

    including more than half a dozen of the world’s most distinguished Tocharianists.

    Are there more than a dozen Tocharianists in total in the world? I didn't dare hope!

    Michael Witzel has favored this, the (Indo-)Aryan Migration view, on linguistic and textual grounds since at least 1955 and was constantly criticized for saying so.

    As far as I know, the migration view has always been mainstream at least outside of India since the early 19th century, and Witzel is just the only one who even bothered to argue with the Hindutva types, not to mention the Vedic creationists.

    (This isn't to belittle Witzel's papers! They're great.)

  3. David Marjanović said,

    June 23, 2017 @ 4:38 am

    Ah – "migration view" means two things: language and people. That Indo-European languages are spoken in India due to a migration has long been the mainstream view; how large that migration was in proportion to the previously existing population of India, and therefore how much of the ancestry of the current population comes from this migration, has been controversial.

  4. Eidolon said,

    June 26, 2017 @ 7:59 pm

    Three aspects of the Indo-Aryan thesis have been controversial since its inception: the source of the migration, the scale of the migration, and the nature of the migration.

    With respect to source, the steppe/Kurgan theory of the origin of Indo-European has long been the most popular view, from what I understand, but the margin of popularity shifted over time. The Anatolian hypothesis – that is, the idea that Indo-European originated in the Near East – has been a potent challenger, as was the idea that Indo-European was "indigenous" to Europe. These alternatives are not irrelevant to the Indo-Aryan debate, since Hindu nationalists have long argued a variation of the Anatolian hypothesis in saying that Indo-Aryan was "native" to the Indian subcontinent.

    With respect to scale, the question is really to what degree the Indo-Aryans, represented by the Vedic civilization, replaced the Indus Valley civilization, thought to be "native." Since much of latter day Indian culture owns its foundations to Vedic civilization, including almost all of the literary tradition, writing having arrived only with the Vedic stage, the question takes on special significance and is often a mine field for bitter disputes.

    Lastly, I recall that the nature of the migration was also a heated area of dispute. The 19th century European view was generally that the Aryans were powerful warriors who subjugated the natives and created the Indian caste system in which they were the ruling class. Thus, Aryans were both conquerors and bringers of civilization. You can imagine how such a narrative was a nice fit to British interests, so it's perfectly understandable that Hindu nationalists would have opposed it on that ground alone. I recall counter arguments to the effect that the Aryans were actually simple immigrants who coexisted peacefully with the natives until the collapse of the Indus Valley civilization. Don't know whether such a line of argument can still stand in light of recent evidence.

    Whatever the case, the controversy surrounding the Indo-Aryan migration theory has a long history and is deeply intertwined with both support of and opposition to British imperialism, which in India ended only 70 years ago. It's fine and well to call it Hindu nationalism, as though it is a fringe theory even within India, but I don't think that does the controversy proper service. Many Indians are very invested in refuting the 19th century version of the Indo-Aryan migration theory, and Western academics in the age of post-colonialism has generally been sympathetic to them.

    But, as recent studies show, there is a limit to what can be justified on the basis of redressing the past. Indians will have to come up with a new source of pride and dignity than the idea of an indigenous beginning to Hindu civilization. What's ironic, though, is that they can take inspiration in such matters from none other than Europeans, the other major recipient of the steppe/Kurgan male-biased invasions/migrations.

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