Download Button Example

Passengers at Patna Junction on Thursday, April 8. (Rahul Sharma/TOI, BCCL, Patna) — Representational image
(Rahul Sharma/TOI, BCCL, Patna)

For decades, scientists have been piecing together the human story through the language of genes. However, global genetic studies have largely overlooked India. But now, a groundbreaking study co-authored by Indian and American researchers has revealed fascinating details about the origins of India's Iranian ancestry, the timing of ancient hunter-gatherer settlements, and a surprising discovery: a remarkably rich diversity of genes from Neanderthals and Denisovans.

The research team, led by population geneticist Priya Moorjani, delved deeper by analysing a much larger sample of modern Indians than ever before. This vast dataset, encompassing individuals from various regions, languages, tribes, and castes, provides a more nuanced picture.

This study begins by confirming the long-held understanding that most Indians are a blend of three ancestral groups: hunter-gatherers who inhabited the region for millennia, Iranian-related farmers who arrived between 4700 and 3000 BCE and herders from the Eurasian steppes who migrated sometime after 3000 BCE.

To pinpoint the origin of the Iranian-linked farmers, researchers analysed ancient DNA from groups with Iranian ancestry predating their arrival in India. Simulations revealed a close match with farmers from Sarazm, an ancient agricultural centre in present-day Tajikistan. This suggests a direct connection, with evidence of trade and cultural exchange between the two regions. Archaeologist Michael Frachetti finds this compelling, highlighting the interconnectedness of ancient societies.

However, Gyaneshwer Chaubey, a biological anthropologist, cautions that the scarcity of ancient DNA samples from India might leave out other contributing populations.

The study delves even further back in time, exploring the mystery of 80,000-year-old stone tools found in India. While the makers remain unidentified, the genetic data suggests they were part of a single migration out of Africa roughly 50,000 years ago.

Intriguingly, the research also revealed that Indians, like Europeans, possess 1-2% Neanderthal and Denisovan ancestry. However, the real surprise lies in the sheer variety of these archaic genes found in Indians. The study recovered a staggering 90% of all known Neanderthal genes that have entered human populations, significantly more than similar studies conducted elsewhere.

Researchers propose two possible explanations: either ancient humans encountered a large, diverse population of Neanderthals and Denisovans in India (whose fossils are yet to be found), or India's geography and social practices might have preserved a wider range of these archaic genes compared to other regions.

This groundbreaking research opens doors to numerous future studies. As Witt emphasises, "There are so many possibilities, so many populations coming together". By combining genetics with archaeology, we may well unlock several more mysteries and gain a deeper appreciation for the rich tapestry that is Indian and South Asian ancestry.

For weather, science, space, and COVID-19 updates on the go, download The Weather Channel App (on Android and iOS store). It's free!

Science

Indians Have the Most Diverse Neanderthal Ancestry in the World, Massive Genetic Study Reveals!