Two recent studies on ancient DNA and migrations into South Asia appeared at the same time in two of the most prestigious journals of their disciplines, one in Science, and one in Cell. Both share a number of common authors and have used Harvard’s genetics laboratory resources. Each of the papers are important in their own right. The Science paper reports ancient DNA from 523 samples from a number of sites in Iran, Central Asia and Anatolia, and comparing it to the current population in the region and in south Asia. This study has increased our number of of such ancient DNA samples by fully 25%.
While the Cell paper reports only one such sample, it is the only sample till date from anywhere in south Asia, from an Indus Valley site in the heyday of the Indus Valley Civilisation. As one of the authors commented, ancient DNA is better preserved in climates that are cold and dry, both of which India is not. Of the 61 skeletons from a Rakhigarhi burial site, only one yielded enough ancient DNA that could be sequenced properly. This, for the scientific community, is indeed a major achievement by the group. Vagheesh Narasimhan, one of the lead authors in both the papers, and David Reich, who heads the Harvard laboratory has described both the difficulties and also the methods they used to amplify the ancient DNA signal from the background noise of other contaminants.
We have covered in these columns the earlier results (available in an earlier version in bioRxiv) of the work of the Reich group in Harvard and their associates spanning across the world including India. They had shown that migration of the people from the steppes region between the Black Sea and the Caspian Sea is visible in ancient DNA, explaining the current genetics profile of the European people as well as the South Asian population. This distribution also seem to map closely the current distribution of languages groups known as the Indo-European group of languages. In South Asia, the current genetic distribution in the population shows a higher prevalence of the steppes ancestry in the male Brahmin population in North India. There is decline of this signature as we go to the south or to the east, therefore identifying the entry of the steppes people from the Northwest South Asia. The steppes signature is much weaker in the female population as we go down the Brahmanical caste hierarchy. The current results published in the Science only strengthens this picture of the bioRxiv version with even more data samples.
The real importance of the Science paper is reading it along with the Rakhigarhi paper in Cell. The Cell paper shows that the single skeleton that yielded ancient DNA was of a woman who was ceremonially buried roughly about 4,500-5,000 years ago. This would mean it predated the steppes migration into South Asia which takes place at least 600-1000 years after that. The Rakhigarhi ancient DNA shows the absence of any steppes signature, and therefore strengthens the archaeological and other evidence that the Indus Valley Civilisation was built by people who do not have the steppes signature. This is unlike the genetic composition of people in the same region today, or that of “upper” caste men in South Asia today.
Even more striking is the finding regarding 11 skeletons in two sites, Sahr-i-Shokta in Eastern Iran, and in Gonur in modern Turkmenistan, a part of the Bactria-Margiana Archaeological Complex (BMAC). These 11 skeletons have no relation to the DNA recovered from other skeletons recovered from the same sites, but are genetically very close to the Rakhigarhi DNA. And all the 12—11 from Gonur and Sahr-i-Shokta and one from Rakhigarhi—show strong South Asian ancient population markers, apart from that of ancient Iranian hunter gatherers. Use of the DNA profiles of the 11 as well as the one from Rakhigarhi gives us a better understanding of the Indus Valley Civilisation population.
With this, we can now make two statements. One, the Indus Valley people had trading outposts in Gonur and Sahr-i-Shokta, but did not intermarry with the local population. Second, the skeletons in Rakhigarhi, Gonur and Sahr-i-Shokta do not show steppes signature in this period, but the steppes signature shows up in later periods and in the current populations of the area. Clearly, all the three sites were yet to see a steppes migration in this period.
The other striking find is that the Indus Valley people—the single Rakhigarhi skeleton and the other 11 in Gonur and Sahr-i-Shokta—though closely related to the Zagros mountains hunter gatherer population, had split from them about 12,000 years back. This break pre-dates the birth of agriculture in Zagros mountains and evidence that agriculture originated independently in the Indus Valley, as it did in Anatolia and in Zagros mountains. It is not Iranian farmers who had migrated to the Indus Valley bringing agriculture with them, but their forefathers, who were still hunter gatherers, entered South Asia from the Northwest, and then developed agriculture independently in the Indus Valley.
The Fertile Crescent had two places in which agriculture developed independently; there were bi-directional flows between the two. Similar gene flows did not happen between the Zagros mountain people and the Indus Valley people after they broke off as hunter gatherer populations, meaning knowledge of agriculture could have been shared, but no significant migrations or inter marriage.
Prof. Shinde, formerly the vice chancellor of Deccan College, headed the Rakhigarhi digs and provided Pof. Reich’s group with the Rakhigarhi skeletons. He is one of the lead authors of the Rakhigarhi paper. He is a known associate of the Rashtriya Swayamsevak Sangh (RSS) and very much a part of their science organisation Vijnana Bharati’s activities. In a press conference, he asserted that somehow the genetic evidence from Rakhigarhi shows that there was no Aryan invasion, and the Indus Valley people spoke Sanskrit. The absurdity of asserting what language the Indus Valley people spoke from ancient DNA is obvious. No DNA from any human being is an indication of what language they spoke. Prof. Shinde is an archaeologist, and asserting his belief on the basis of ancient DNA evidence is straying far outside his academic competence. The other lead authors including Niraj Rai from the Birbal Sahni Institute, Lucknow and Vagesh Narasimhan from Harvard, have “politely” pointed out, that the ancient DNA evidence from Rakhigarhi does not bear out Prof. Shinde’s contention.
In other countries, such studies of ancient DNA and their findings are of interest only to scholars. In India, it is immediately a matter of controversy. The Hindutva brigade, as a corner stone of their theory, have the belief that Sanskrit speakers and the Vedic texts are indigenous. If they are shown to have originated from outside India, then their communal agenda of India being the pitrubhumi (fatherland) and the punyabhumi (holy land) of the Hindus and therefore, Hindus having a higher claim to this land, would have to be discarded. The Rig Vedic Aryans would, instead, be only one among the many other invaders who have come into India.
For the RSS and other Hindu supremacists, any evidence that Vedic Sanskrit speakers, who spoke an Indo-European language, came from outside, has to be rejected; not on the basis of evidence but on the basis of belief. The former Chairman of Indian Council of Historical Research (ICHR), Prof. YS Rao even went to the extent of saying our oral history – our mythologies and epics – are not only to be taken as real history, but given a higher position as evidence than any archaeological or linguistic evidence. To this list of evidence that have a “lower” position for the Sanghis, must be now added genetic evidence; to be accepted if it validates the thesis that Indo-European language speakers originate from South Asia, but rejected if it does not.
Also read: The Peopling of South Asia and the New Genomic Evidence