A new study of South Asian genetics casts deep doubt upon the Hindu nationalist theory that an ancient “Aryan” population, indigenous to India, gave birth to Hinduism and its liturgical language Sanskrit.
The paper, titled The Genomic Formation of South and Central Asia, instead suggests that India was home to several mixed populations, and that pastoralists who moved to India from Central Asia are likely to have brought with them an Indo-European language closely related to Sanskrit.
The world’s Indo-European languages, thought to spring from a common ancestral tongue, include not only Sanskrit and Hindi but also English, French, Greek, Russian and dozens of other modern languages.
Published on Saturday, the paper summarises a decade’s worth of research and collaboration by 92 scientists and scholars around the world, including geneticists, archaeologists, linguists, molecular biologists and anthropologists. The research relied upon DNA samples from 612 human remains dating from 6,200 BC to 1 AD, as well as samples from 1,789 people across 246 ethnographic groups in Central and South Asia.
The collaboration was essential, said Vasant Shinde, an archaeologist at Deccan College in Pune and one of the study’s authors.
"We've been excavating a number of sites, but by ourselves we weren't able to learn about the movement of people. So we started collaborating with genetic scientists," he told The National.
Mr Shinde works on digs in north-western India, where the Indus Valley civilisation flourished from about 3,000 BC to 1,400 BC. While the digs yielded plenty of artefacts, they divulged no details about where the people who built the civilisation had come from, what language they spoke or what happened to them.
Leading Hindu nationalists, who have claimed that the subcontinent has always been inhabited by Hindus, insisted that the Indus Valley civilisation gave birth to Sanskrit and to the Vedas, the principal Hindu texts.
M S Golwalkar, a nationalist ideologue who died in 1973, wrote that Hindus had been “in undisputed and undisturbed possession of this land for eight or even ten thousand years” before Muslim and Christian invaders arrived. He also argued that an indigenous “Aryan” race left India and spread to Europe, taking Sanskrit along.
Golwalkar’s hypothesis, championed by others in the Hindu right, “was always an oddball theory”, said Tony Joseph, a writer working on a book about South Asian genetic research. “They couldn’t explain how all these languages were linked, so they said that they all came out of India.”
As long as discussions were restricted to linguistics, Mr Joseph said, this was at least an arguable theory. But the advance of genetics over the past five years, particularly in testing ancient samples, has contradicted Golwalkar’s hypothesis.
The new study is the most definitive yet, he said.
By following the spread of DNA markers, the paper notes that the Indus Valley civilisation was probably mixture of two populations: one, the descendants of agriculturalists who arrived around or before 4,700BC from what is now Iran; the other, descendants of hunter-gatherers thought to be the original humans in South Asia.
One theory speculates that the hunter-gatherers came out of a line of humans who migrated out of Africa about 60,000 years ago. But nothing has been proven, Mr Shinde said. “Where did these first people come from? We just don’t know yet.”
There is still no conclusive proof as to what language the Indus Valley civilisation spoke. But with the pastoralists moving out of the Central Asian steppes, towards Europe but also into South Asia, we have more knowledge, Mr Joseph said.
“There is a striking correlation between where the steppe pastoralists went and where Indo-European languages spread.”
The new study finds that the pastoralists began streaming into South Asia around 2,000 BC. They mixed with the Indus Valley populations, resulting in the genetic pool from which hundreds of millions of Indians draw their lineage. Groups from the Indus Valley populations also moved farther south in India, mixing not with the pastoralists but with indigenous South Asian hunter-gatherer communities.
“We show that Indus Periphery-related people [of the Indus Valley civilisation] are the single most important source of ancestry in South Asia,” the study’s authors wrote.
“There was trade, there was movement – a lot of mixing of populations happened,” Mr Shinde said. “It was an ongoing process.”
Some westward movement did occur as well, the study adds, having found small but significant signs of South Asian hunter-gatherer DNA in populations west of the Indus Valley.
Mr Joseph, who has written extensively on genetic research into ancient Indian populations, said that he often received criticism from Hindu nationalists for his pieces. “That is to be expected,” he said with a laugh. “These are hot-button topics.”
“I am curious now to see how they respond to this study.”