Niraj Rai, the head of the Ancient DNA Laboratory at Lucknow’s Birbal Sahni Institute of Palaeosciences (BSIP), where the DNA samples from the Harappan site of Rakhigarhi in Haryana are being analysed, has revealed that a forthcoming paper on the work will show that there is no steppe contribution to the DNA of the Harappan people. This result comes close to settling one of the most important outstanding issues regarding the Indian past—the question concerning the possible migration of Indo-European language speakers from the Pontic steppe in Central Asia into north-west India.

“It will show that there is no steppe contribution to the Indus Valley DNA,” Rai said. “The Indus Valley people were indigenous, but in the sense that their DNA had contributions from near eastern Iranian farmers mixed with the Indian hunter-gatherer DNA, that is still reflected in the DNA of the people of the Andaman islands.” He added that the paper based on the examination of the Rakhigarhi samples would soon be published on bioRxiv (pronounced “bio-archive”), a preprint repository of papers in the life sciences.

The Rakhigarhi samples belonged to individuals who lived approximately 4,600 years ago, during the peak of the Indus Valley Civilisation. The absence of steppe DNA markers in the samples indicates that, at that point in time, there had been no intermingling between the steppe pastoralists and the population of the Indus Valley Civilisation.

The bones of four people were excavated in Rakhigarhi. According to Rai, three samples from Rakhigarhi were morphologically well preserved, but the DNA that was extracted from them was highly degraded. “But we were able to obtain a good sample,” he said. The excavation and extraction of samples has been carried out under Vasant Shinde, a senior archaeologist who is the vice-chancellor at the Deccan College Post Graduate and Research Institute in Pune. The Rakhigarhi study, Rai said, provides direct evidence for the claims of a paper published in preprint on bioRxiv in March 2018, which outlines a comprehensive model for the settlement of different populations within the subcontinent.

Shinde and Rai are among 91 co-authors of this March 2018 paper, titled “The Genomic Formation of South and Central Asia.” The study was carried out at the laboratory for ancient DNA at the Harvard Medical School, which is run by David Reich, a geneticist and a professor in the college’s department of genetics. The model proposed in the paper elaborates on a 2009 paper from the lab that suggests the current population of India is largely an admixture in varying proportion of two older populations—the Ancestral North Indians (ANI) and the Ancestral South Indians (ASI).