June 16, June 19, 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: Genetic research based on an avalanche of new DNA evidence is making scientists around the world converge on an unambiguous answer: This may come as a surprise to many — and a shock to some — because the dominant narrative in recent years has been that genetics research had thoroughly disproved the Aryan migration theory.
This interpretation was always a bit of a stretch as anyone who read the nuanced scientific papers in the original knew. But now it has broken apart altogether under a flood of new data on Y-chromosomes or chromosomes that are transmitted through the male parental line, from father to son. Lines of descent Until recently, only data on mtDNA or matrilineal DNA, transmitted only from mother to daughter were available and that seemed to suggest there was little external infusion into the Indian gene pool over the last 12, years or so.
New Y-DNA data has turned that conclusion upside down, with strong evidence of external infusion of genes into the Indian male lineage during the period in question. In other words, those who migrated were predominantly male and, therefore, those gene flows do not really show up in the mtDNA data.
On the other hand, they do show up in the Y-DNA data: Pontic-Caspian Steppe is seen as the region from where R1a spread both west and east, splitting into different sub-branches along the way.
Richards of the University of Huddersfield, U. In an email exchange, Prof. Three years ago, a team of 32 scientists he led published a massive study mapping the distribution and linkages of R1a. It used a panel of 16, male subjects from populations across Eurasia. Ninety-six per cent of the R1a samples in Europe belonged to sub-haplogroup Z, while The two groups diverged from each other only about 5, years ago.
So if you want to know the approximate period when Indo-European language speakers came and rapidly spread across India, you need to discover the date when Z93 splintered into its own various subgroups or lineages. We will come back to this later. So in a nutshell: R1a is distributed all over Europe, Central Asia and South Asia; its sub-group Z is distributed only in Europe while another subgroup Z93 is distributed only in parts of Central Asia and South Asia; and three major subgroups of Z93 are distributed only in India, Pakistan, Afghanistan and the Himalayas.
This clear picture of the distribution of R1a has finally put paid to an earlier hypothesis that this haplogroup perhaps originated in India and then spread outwards. This hypothesis was based on the erroneous assumption that R1a lineages in India had huge diversity compared to other regions, which could be indicative of its origin here.
Gene-dating the migration Now that we know that there WAS indeed a significant inflow of genes from Central Asia into India in the Bronze Age, can we get a better fix on the timing, especially the splintering of Z93 into its own sub-lineages? Yes, we can; the research paper that answers this question was published just last year, in April , titled: Underhill as one of the 42 co-authors.
This is remarkable, because roughly 4, years ago is when the Indus Valley civilization began falling apart. There is no evidence so far, archaeologically or otherwise, to suggest that one caused the other; it is quite possible that the two events happened to coincide.
The avalanche of new data has been so overwhelming that many scientists who were either sceptical or neutral about significant Bronze Age migrations into India have changed their opinions. Underhill himself is one of them. Underhill says there is no comparison between the kind of data available in and now. With whole genome sequencing, we can now see nearly the entire room, in clearer light. Underhill is not the only one whose older work has been used to argue against Bronze Age migrations by Indo-European language speakers into India.
David Reich, geneticist and professor in the Department of Genetics at the Harvard Medical School, is another one, even though he was very cautious in his older papers. The study also proved that most groups in India today can be approximated as a mixture of these two populations, with the ANI ancestry higher in traditionally upper caste and Indo-European speakers.
However, this theoretical structure was stretched beyond reason and was used to argue that these two groups came to India tens of thousands of years ago, long before the migration of Indo-European language speakers that is supposed to have happened only about 4, to 3, years ago.
In fact, the study had included a strong caveat that suggested the opposite: While they provide an important framework for testing historical hypothesis, they are oversimplifications. For example, the true ancestral populations were probably not homogenous as we assume in our model but instead were likely to have been formed by clusters of related groups that mixed at different times. The spin and the facts But how was this research covered in the media?
The report also carried statements such as: At a later stage, 40, years ago, the ancient north Indians emerged which in turn led to rise in numbers there.
But at some point in time, the ancient north and the ancient south mixed, giving birth to a different set of population. And that is the population which exists now and there is a genetic relationship between the population within India. This stark contrast between what the study says and what the media reports said did not go unnoticed.
In his column for Discover magazine, geneticist Razib Khan said this about the media coverage of the study: In an interview with Edge in February last year, while talking about the thesis that Indo-European languages originated in the Steppes and then spread to both Europe and South Asia, he said: It arrived years ago from the East from the Steppe It corresponds to the time of the composition of the Rigveda, the oldest Hindu religious text, one of the oldest pieces of literature in the world, which describes a mixed society This paper too has been pushed into serving the case against migrations of Indo-European language speakers into India, but the paper itself says no such thing, once again!
The period of around 1,—4, years before present was a time of profound change in India, characterized by the de-urbanization of the Indus civilization, increasing population density in the central and downstream portions of the Gangetic system, shifts in burial practices, and the likely first appearance of Indo-European languages and Vedic religion in the subcontinent.
But it is clear that the authors think its findings fit in well with the traditional reading of the dates for this migration.
In fact, the paper goes on to correlate the ending of population mixing with the shifting attitudes towards mixing of the races in ancient texts. In an email to this writer, Moorjani said as much. In answer to a question about the conclusions of the recent paper of Prof. One by one, therefore, every single one of the genetic arguments that were earlier put forward to make the case against Bronze Age migrations of Indo-European language speakers have been disproved.
The first argument was that there were no major gene flows from outside to India in the last 12, years or so because mtDNA data showed no signs of it. This argument was found faulty when it was shown that Y-DNA did indeed show major gene flows from outside into India within the last to 4, years or so, especially R1a which now forms The reason why mtDNA data behaved differently was that Bronze Age migrations were severely sex-biased.
The second argument put forward was that R1a lineages exhibited much greater diversity in India than elsewhere and, therefore, it must have originated in India and spread outward. This has been proved false because a mammoth, global study of R1a haplogroup published last year showed that R1a lineages in India mostly belong to just three subclades of the R1a-Z93 and they are only about 4, to 4, years old.
The third argument was that there were two ancient groups in India, ANI and ASI, both of which settled here tens of thousands of years earlier, much before the supposed migration of Indo-European languages speakers to India.
This argument was false to begin with because ANI — as the original paper that put forward this theoretical construct itself had warned — is a mixture of multiple migrations, including probably the migration of Indo-European language speakers. Connecting the dots Two additional things should be kept in mind while looking at all this evidence. The first is how multiple studies in different disciplines have arrived at one specific period as an important marker in the history of India: According to the Priya Moorjani et al study, this is when population mixing began on a large scale, leaving few population groups anywhere in the subcontinent untouched.
The Onge in the Andaman and Nicobar Islands are the only ones we know to have been completely unaffected by what must have been a tumultuous period. And according to the David Poznik et al study of on the Y-chromosome, B.
Lastly, from long-established archaeological studies, we also know that BC was around the time when the Indus Valley civilization began to decline. The second is that many studies mentioned in this piece are global in scale, both in terms of the questions they address and in terms of the sampling and research methodology.
For example, the Poznik study that arrived at 4,, years ago as the dating for the splintering of the R1a Z93 lineage, looked at major Y-DNA expansions not just in India, but in four other continental populations.
In the Americas, the study proved the expansion of haplogrop Q1a-M3 around 15, years ago, which fits in with the generally accepted time for the initial colonisation of the continent. So the pieces that are falling in place are not merely in India, but all across the globe. The more the global migration picture gets filled in, the more difficult it will be to overturn the consensus that is forming on how the world got populated.
Nobody explains what is happening now better than Reich: But one must not lose the bigger picture: R1a lineages form only about The vast majority of Indians owe their ancestry mostly to people from other migrations, starting with the original Out of Africa migrations of around 55, to 65, years ago, or the farming-related migrations from West Asia that probably occurred in multiple waves after 10, B.
What is abundantly clear is that we are a multi-source civilization, not a single-source one, drawing its cultural impulses, its tradition and practices from a variety of lineages and migration histories.
The Out of Africa immigrants, the pioneering, fearless explorers who discovered this land originally and settled in it and whose lineages still form the bedrock of our population; those who arrived later with a package of farming techniques and built the Indus Valley civilization whose cultural ideas and practices perhaps enrich much of our traditions today; those who arrived from East Asia, probably bringing with them the practice of rice cultivation and all that goes with it; those who came later with a language called Sanskrit and its associated beliefs and practices and reshaped our society in fundamental ways; and those who came even later for trade or for conquest and chose to stay, all have mingled and contributed to this civilization we call Indian.
We are all migrants. Tony Joseph is a writer and former editor of BusinessWorld.