With the release of two ancient DNA studies on Thursday, scientists may have solved a portion of the mystery around the Indus Valley Civilisation (IVC), also called the Harappan Civilisation, which was spread across northwestern South Asia from 2600 to 1900 BCE.
The two studies — which appeared in journals Cell and Science — show that there was no central Asian Steppe ancestry among the Harappans, indicating that the Steppe pastoralists migrated to India after the decline of the Harappan civilisation.
The study published in Cell, titled “An Ancient Harappan Genome Lacks Ancestry from Steppe Pastoralists or Iranian Farmers”, examined DNA samples extracted from 4,500-year-old skeletal remains of a woman found in Rakhigarhi, the IVC site in Haryana’s Hisar. Archeologist Vasant Shinde, one of the authors of the study, said, “The study conclusively points to the fact that agriculture is indigenous to the region; that there is no evidence of large-scale migration of any kind in the Harappan civilisation; that hunter-gatherers of the region gradually became farmers; and most importantly, Harappan people are the same as Vedic people.”
The study states: “The individual we sequenced fits as a mixture of people related to ancient Iranians (the largest component) and Southeast Asian hunter-gatherers, a unique profile that matches ancient DNA from 11 genetic outliers from sites in Iran and Turkmenistan in cultural communication with the IVC. These individuals had little if any Steppe pastoralist-derived ancestry, showing that it was not ubiquitous in northwest South Asia during the IVC as it is today.”
Tony Joseph, who authored Early Indians: The Story of Our Ancestors and Where We Came From (2018), told The Indian Express, “The Cell study says that these 12 DNA samples tell us that the Harappans were a mixture of First Indians (or out of Africa migrants who first peopled India around 65,000 years ago and then went on to populate southeast Asia etc) and west Asians from the Zagros region of Iran. It also says these migrants from west Asia reached India before agriculture began anywhere, so in that sense they may not have been farmers themselves yet. In other words, farming may have begun independently in India as my book, Early Indians, argued.”
The study published in Science is the largest ever study of ancient human DNA, which analyses the genomes of 523 ancient individuals spanning the last 8,000 years, mostly from central Asia and northernmost South Asia.
This was done to “elucidate the extent to which the major cultural transformations of farming, pastoralism, and shifts in the distribution of languages in Eurasia were accompanied by movement of people”.
As per the Science study, the main population of the Bronze Age Bactria Margiana Archaeological Complex (BMAC) “carried no ancestry from Steppe pastoralists and did not contribute substantially to later south Asians. However, Steppe pastoralist ancestry appeared in outlier individuals at BMAC sites by the turn of the second millennium BCE around the same time as it appeared on the southern Steppe”.
The study notes that “after IVC’s decline, this population mixed with northwestern groups with Steppe ancestry to form the ‘Ancient North Indians (ANI)’ and also mixed with southeastern groups to form the ‘Ancestral South Indians (ASI)’, whose direct descendants today live in tribal groups in southern India”.
The study states that ANI and ASI “drive the main gradient of genetic variation in south Asia today”.
Joseph added, “The study in Science links the Steppe migrations into South Asia with the spread of Indo-European languages to India, just as it links the Steppe migrations into Europe with the spread of Indo-European languages to Europe. Both Europe and South Asia saw major prehistoric migrations from west Asia, and much later, from Central Asia, says the Science study. The study also says that the language of the Harappan civilisation was likely to be have been Dravidian.”