The largest-ever study of ancient human DNA, that analyses the genomes of 524 ancient individuals, along with a study of the first genome of an individual from the ancient Indus Valley Civilisation, was released Thursday. Both studies provide never seen before details about the shifting ancestry of Central and South Asian populations which have remained understudied parts of the world for several years.
The pair of studies published online in Science and Cell also provides insights into questions that have intrigued researchers about the origins of farming and the source of Indo-European languages in South and Central Asia.
The study in Cell traces DNA from a woman in a 4500-year-old burial site in Rakhigarhi and finds that the genome lacks any ancestry from Steppe pastoralists or Iranian Farmers. Simply put, the study confirms that a mixed population made up the Harappan Civilization of first Indians and West Asians and Steppe pastoralists who brought Indo-Aryan languages to India were not present in the region at the time.
“It means the West Asian migrants who mixed with the First Indians to form the population that spread agriculture in northwestern India and built the Harappan Civilization were not yet farmers when they came to India. They came before agriculture had begun anywhere in the world,” said Tony Joseph, author of ‘Early Indians’ in a tweet. This is significant in that it explains that farming is likely to have started independently in India through an exchange of ideas rather than a mass migration as such.
As for the study in Science, it confirms earlier findings that the Steppe pastoralists arrived in India in the first half of the 2nd millennium.
“Using data from ancient individuals from the Swat Valley of northernmost South Asia, we show that Steppe ancestry then integrated further south in the first half of the 2nd millennium BCE, contributing up to 30 per cent of the ancestry of modern groups,” the paper states. “The Steppe ancestry in South Asia has the same profile as that in Bronze Age Eastern Europe, tracking a movement of people that affected both regions and that likely spread the unique features shared between Indo-Iranian and Balto-Slavic languages,” the paper adds.
The team of researchers included geneticists, archaeologists, and anthropologists from North America, Europe, Central Asia, and South Asia. The work increased the worldwide total of published ancient genomes by about 25 percent, said a statement by the Harvard Medical School. The study integrates genetics with archaeology and linguistics.
The study adds to earlier research including a 2015 paper by David Reich and his colleagues, who are the co-senior author of both papers and a professor of genetics in the Blavatnik Institute at Harvard Medical School, that Indo-European languages arrived in Europe via the steppe. This study now makes a similar case for South Asia by showing that present-day South Asians have little if any ancestry from farmers with Anatolian roots, said the statement.