A study of DNA from skeletal remains of the Harappan cemetery at Rakhigarhi argues that the hunter-gatherers of South Asia have an independent origin. The researchers contend that the theory of the Harappans having Steppe pastoral. The finding also negates the hypothesis about mass migration during Harappan times from outside South Asia.

The study was published in the journal Cell.

Theory of independent origin

The Indus Valley Civilization (IVC), also known as the Harappan Civilisation, was spread over northwestern South Asia from 2600 to 1900 BCE and was one of the first large-scale urban societies of the ancient world, characterised by systematic town planning, elaborate drainage systems, granaries, and standardisation of weights and measures.

The inhabitants of the IVC were cosmopolitan, with multiple cultural groups living together in large regional urban centres like Harappa (Punjab), Mohenjo-daro (Sindh), Rakhigarhi (Haryana), Dholavira (Kutch/Gujarat), and Ganweriwala (Cholistan).

The researchers had successfully sequenced the first genome of an individual from Harappa and combining it with archaeological data, found that hunter-gatherers of South Asia had an independent origin.

The ancient woman’s genome matched those of 11 other ancient people who lived in what is now Iran and Turkmenistan at sites known to have exchanged objects with the Indus Valley Civilization. All 12 had a distinctive mix of ancestry, including a lineage related to Southeast Asian hunter-gatherers and an Iranian-related lineage specific to South Asia.

“They do not contain genome from either the Steppe region or ancient Iranian farmers. The genetic continuity from hunter gatherer to modern times is visible in the DNA results,” said Vasant Shinde, the professor who headed the Rakhigarhi project.

Spreading of languages

Geneticists, archaeologists and anthropologists from North America, Europe, Central Asia and South Asia analysed the genomes of 524 never before-studied ancient individuals. The work increased the worldwide total of published ancient genomes by about 25 per cent.

By comparing these genomes to one another and to previously sequenced genomes, and by putting the information into context alongside archaeological, linguistic and other records, the researchers filled in many of the key details about who lived in various parts of this region from the Mesolithic Era (about 12,000 years ago) to the Iron Age (until around 2,000 years ago) and how they relate to the people who live there today.

Indo-European languages - including Hindi/Urdu, Bengali, Punjabi, Persian, Russian, English, Spanish, Gaelic and more than 400 others - make up the largest language family on Earth.

For decades, researchers have debated how Indo-European languages came to be spoken from the British Isles to South Asia.

Now, the largest-ever study of ancient human DNA suggests that the answer may lie with a mass migration of Bronze Age herders from the Eurasian Steppes, starting 5,000 years ago, westward to Europe and east to Asia.

Vagheesh Narasimhan, co-first author of the paper, said that the role of population movements over the past 10,000 years was key to understanding linguistic changes and the transition from hunter-gatherer activities to farming.

The evidence in favor of a Steppe origin for Indo-European languages is the detection of genetic patterns that connect speakers of the Indo-Iranian and Balto-Slavic branches of Indo-European.

Origins of farming

The study also tries to find an answer to another long-standing debate about whether the change from a hunting and gathering economy to one based on farming was driven more by movements of people, the copying of ideas or local invention.

In Europe, ancient DNA studies have shown that agriculture arrived along with an influx of people with ancestry from Anatolia (present-day Turkey).

In South Asia, however, the story appears quite different. Not only did the researchers find no trace of the Anatolian-related ancestry that is a hallmark of the spread of farming to the west, but the Iranian-related ancestry they detected in South Asians comes from a lineage that separated from ancient Iranian farmers and hunter-gatherers before those groups split from each other.

The researchers concluded that farming in South Asia was not due to the movement of people from the earlier farming cultures of the west; instead, local foragers adopted it.

“We can rule out a large-scale spread of farmers with Anatolian roots into South Asia, the centerpiece of the Anatolian hypothesis that such movement brought farming and Indo-European languages into the region,” said co-author David Reich from Harvard Medical School.