Indian Y chromosomes

A prehistory of Indian Y chromosomes: evaluating demic diffusion scenarios.

2005

Understanding the genetic origins and demographic history of Indian populations is important both for questions concerning the early settlement of Eurasia and more recent events, including the appearance of Indo-Aryan languages and settled agriculture in the subcontinent. Although there is general agreement that Indian caste and tribal populations share a common late Pleistocene maternal ancestry in India, some studies of the Y-chromosome markers have suggested a recent, substantial incursion from Central or West Eurasia. To investigate the origin of paternal lineages of Indian populations, 936 Y chromosomes, representing 32 tribal and 45 caste groups from all four major linguistic groups of India, were analyzed for 38 single-nucleotide polymorphic markers. Phylogeography of the major Y-chromosomal haplogroups in India, genetic distance, and admixture analyses all indicate that the recent external contribution to Dravidian- and Hindi-speaking caste groups has been low. The sharing of some Y-chromosomal haplogroups between Indian and Central Asian populations is most parsimoniously explained by a deep, common ancestry between the two regions, with diffusion of some Indian-specific lineages northward. The Y-chromosomal data consistently suggest a largely South Asian origin for Indian caste communities and therefore argue against any major influx, from regions north and west of India, of people associated either with the development of agriculture or the spread of the Indo-Aryan language family. The dyadic Y-chromosome composition of Tibeto-Burman speakers of India, however, can be attributed to a recent demographic process, which appears to have absorbed and overlain populations who previously spoke Austro-Asiatic languages

 

y-chr-freq-india

I have to agree with the paper that only J2 shows a clear near Eastern origin.

9 responses to “Indian Y chromosomes

  1. “only J2 shows a clear near Eastern origin”.

    And both Os show aa eastern origin. But no Indian haplogroups have spread in the other direction, into East Asia. What’s all this I hear about the ease of travel along a southern coastal route?

  2. But no Indian haplogroups have spread in the other direction, into East Asia.

    In fact haplogroup H, the only clade shown in that map (but look at the supplemental material for another map of with clades like R2) that is neatly Indian, has a presence in SE Asia: 5-10% is more than just significative.

    Also the strong presence of O2a among Orissan tribals appears to mean the opposite route of migration.

    The route between South and SE Asia anyhow has a major barrier in the Ganges Delta (a huge swamp in the past) and the mountainous jungle east of it. But it’s very likely that neither of these was a meaningful barrier for canoing peoples of the UP, who anyhow, it’s argued, lived mostly on fish and seafood.

    You have then only two possible routes between South and SE Asia: the inland route along the Brahmaputra and its hilly jungle or the coastal route along the mangle swamps. Probably both were practiced by more or less small numbers of founder foreparents of East Asian, Oceanian and American peoples.

    Anyhow,within South Asia and also within SE Asia, the coastal route is not the only possible one: some inland routes are similarly easy.

  3. The Y-chromosomal data consistently suggest a largely South Asian origin for Indian caste communities and therefore argue against any major influx, from regions north and west of India, of people associated either with the development of agriculture or the spread of the Indo-Aryan language family.

    This makes no sense, sorry. R1a must have arrived from the steppes. The apportion and diversity in South Asia is not larger than in Eastern Europe or some areas of Central Asia. The matches between Indian and, say, Polish R1a are extremely close and, additionally there’s no archaologically possible explanation for any out-of-India model for this clade. R1a is IE/Kurgan, Scythian at most (for the closest matches across the steppes).

    Also haplogroup L, while centered in Pakistan maybe, does appear to me to have spread along with J2 within Neolithic.

    The only truly South Asian “aboriginal” major clades are H and R2, but the latter is related to the huge Eurasian and American P family, so it may also have originated NW of the subcontinent (or NW within it), though in quite old times. H in any case does appear as a true early founder effect and a 100% aboriginal clade in South Asia.

  4. “But it’s very likely that neither of these was a meaningful barrier for canoing peoples of the UP”.

    But humans reached Australia before the Upper Paleolithic.

    “some inland routes are similarly easy”.

    Which ones?

  5. Oh. The H could well have spread with Hinduism into SE Asia and there’s no reason to blieve the O2a in Orissan tribals didn’t come from SE Asia once humans had invented canoes.

  6. Further to the above:

    Even if mainly for political reasons the mountains and swamps of Burma or Myanmar are today virtually impassable. But Northeast India, Bangladesh and Burma have probably only been inhabited since humans invented boats, and were impassable before then.

    Furhter north the Himalayas form a virtually impervious barrier except for a few human groups adapted to mountains who have been able to expand onto neighbouring lowlands to some extent.

    As demonstrated by current events the most porous boundary between the Indian subcontinent, or what I usually refer to as the Indian subpoint of the human star, and the rest of the world has always been the mountainous boundary between Afghanistan and Pakistan. We know from all sorts of evidence that there has been almost constant back and forth movement through the region.

    Ancient humans too are much more likely to have entered India by this route rather than the much less-used route along the coast.

    To reach Afghanistan humans must first move through the Iranian Plateau. Once there cold is the only thing preventing their rapid northward movement and consequent proximity to the much more permeable Tien Shan and Altai Mountains, and onto what later became the silk route. Thereby opening a probably faster route to SE Asia than that along the coast.

  7. …before the Upper Paleolithic.

    I stand corrected, MP too.

    Which ones?

    We have discussed this before: GIS modeling found that the Narmada-Son-Ganges route and another one along the Krishna river are similarly easy to walk. Additionally both routes are rich in Paleolithic remains (both MP and UP).

    Oh. The H could well have spread with Hinduism into SE Asia and there’s no reason to blieve the O2a in Orissan tribals didn’t come from SE Asia once humans had invented canoes.

    Did I say otherwise?

    Anyhow there are some mtDNA clades that are shared between SE and South Asia (M33,M34).

    But Northeast India, Bangladesh and Burma have probably only been inhabited since humans invented boats, and were impassable before then.

    Maybe not but, in any case, I think that canoes and rafts are as old a humankind or nearly so.

    I understand that there are two possible routes between South and SE Asia: the Brahmaputra and the purely coastal one (canoing throuugh mangle swamps full of food and mosquitoes). Neither of them appears to have been heavily transited after Paleolithic (with the AA exception).

    As demonstrated by current events the most porous boundary between the Indian subcontinent, or what I usually refer to as the Indian subpoint of the human star, and the rest of the world has always been the mountainous boundary between Afghanistan and Pakistan. We know from all sorts of evidence that there has been almost constant back and forth movement through the region.

    Ancient humans too are much more likely to have entered India by this route rather than the much less-used route along the coast.

    To reach Afghanistan humans must first move through the Iranian Plateau. Once there cold is the only thing preventing their rapid northward movement and consequent proximity to the much more permeable Tien Shan and Altai Mountains, and onto what later became the silk route. Thereby opening a probably faster route to SE Asia than that along the coast.

    The GIS model was set to begin in the Zagros (or somewhere else in Northern Iran, can’t recall – maybe the Caspian shores?) and still the coastal route was the only one chosen (i.e. realistic). Only once in India the “land” (riverine) routes became viable.

    The Hindu Kush has certanly been porous in recent times (since the Bronze Age, long after confirmed horse domestication) but this is not so clear for the past. Of course Afghan archaeology and genetics still have to unveil its secrets but overall it seems to me that the deserts of NE Iran and Afghanistan were more a barrier than a passway.

    We have to understand that before the domestication and spread of horses, and later camels, the semideserts were a very hostile zone and the true deserts were just out of any consideration. In that time nevertheless sailing was not just possible but seemingly frequent between Mesopotamia and historical India – if we are to judge by Sumerian documents.

    The earliest know Neolithic in South Asia also correlates with a rather southern path: it’s in Baluchistan.

    All this doesn’t mean that the inland route has not been used at all (presumably under favorable climatic conditions) and the early spread of humans out of South Asia may have taken that route into Central Asia and then to West Asia. At least this seems apparent for Y-DNA P spread and the realtively aboundance of early human remains (maybe precursors of Aurignacian) in that area.

  8. “I think that canoes and rafts are as old a humankind or nearly so”.

    I doubt that very much.

    “Neither of them appears to have been heavily transited after Paleolithic”.

    I would have thougt either of these routes would be much easier to use after the Paleolithic than before it. Boats have become much more efficient, as have axes to clear the forest, etc.

    “In that time nevertheless sailing was not just possible but seemingly frequent between Mesopotamia and historical India – if we are to judge by Sumerian documents”.

    But that’s long after the Paleolithic.

    “Anyhow there are some mtDNA clades that are shared between SE and South Asia”.

    But when were they exchanged?

    “The Hindu Kush has certanly been porous in recent times (since the Bronze Age, long after confirmed horse domestication”.

    Probably before then. The Burushaski language is probably fairly ancient in the region, almost certainly before the Indo-European expansion anyway.

    “All this doesn’t mean that the inland route has not been used at all (presumably under favorable climatic conditions)”.

    And at such times your comment, “the deserts of NE Iran and Afghanistan were more a barrier than a passway” would no longer hold.

    “GIS modeling found that the Narmada-Son-Ganges route and another one along the Krishna river are similarly easy to walk”.

    Where did you get that from? The Narmada is way west and the Krishna way south to be relevant as routes into SE Asia.

  9. Anyway I completely accept that mtDNA line M eventually moved from India into SE Asia. After all early daughter branches Q and E are virtually confined to SE Asia and presumably evolved there. But it is extremely likley that any of these early humans who moved from India into SE Asia did so by land, through the mountains of Burma and South China, not around the coast.

    It would have been no rapid migration. Long before that they first of all had to come into India across the Afghan/Pakistan border (we’ll include Baluchistan in this if you insist, it is in Pakistan), north around the Indus and into India: then south, and as far east as Bangladesh. From here a branch would have had to edge along the southern margin of the Himalayas, all this long before they reached Burma.

    Besides, it seems that the route through Burma may not have been the only route east. It’s pretty obvious that mt haplogroup N didn’t move through India, although N became the majority mtDNA line in Australia. N may have reached the region by what had been an easier route at times.

    N’s early descendant lines are scattered across Central, East and Southeast Asia, and into Australia. The most likely explanation for this distribution is that this is precisely the route N traveled, across Central Asia. It’s relatively easy to follow the various haplogroup, and human, expansions from this time on.

    The two main mtDNA lines outside Africa had originally simply parted company somewhere around the Zagros or Hindu Kush Mountains. Humans as a whole may have done the same thing.

Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out / Change )

Twitter picture

You are commenting using your Twitter account. Log Out / Change )

Facebook photo

You are commenting using your Facebook account. Log Out / Change )

Google+ photo

You are commenting using your Google+ account. Log Out / Change )

Connecting to %s