A major new study has unlocked the secrets of India’s genetic past, revealing how ancient migrations and cultural practices have shaped the health and disease patterns of its people today. Scientists sequenced the complete genomes of 2,762 individuals from across India, representing a wide mix of regions, languages, and communities. This research, published in the journal Cell, is the largest and most detailed analysis of Indian genomes ever conducted.
Ancient Roots: A Single Migration from Africa
The study found that most genetic variation in India can be traced back to a single migration of humans out of Africa around 50,000 years ago. These early settlers mixed with now-extinct human relatives, Neanderthals and Denisovans, before spreading across Asia. Remarkably, Indian genomes contain more varied segments of Neanderthal DNA than any other population studied so far. This unique mix allowed researchers to reconstruct about half of the Neanderthal genome and a fifth of the Denisovan genome using Indian samples.
A Melting Pot of Ancestries
India’s population is a blend of three ancient groups:
– Local hunter-gatherers
– Neolithic farmers from Central Asia
– Steppe pastoralists from Central Asia
Over thousands of years, these groups mixed, creating the diverse gene pool found in India today. However, about 3,500 years ago, many Indian communities began practicing endogamy i.e. marrying within their own group. This led to population “bottlenecks,” where some genetic variants became much more common in certain communities.
Health Impacts: Rare Diseases and Community-Specific Risks
These bottlenecks increased the chances of inheriting two copies of harmful genetic variants, raising the risk of certain rare diseases. For example, a mutation in the BCHE gene, which can cause dangerous reactions to some anesthetics, is common in the Vysya community but rare elsewhere in India. The researchers also identified rare, community-specific variants linked to blood disorders, hearing loss, cystic fibrosis, and phenylketonuria.
Why This Matters
India is home to about 5,000 different ethno-linguistic and religious groups, making it one of the world’s most diverse countries. Yet, Indian populations have been underrepresented in global genetic research. This study fills a major gap, helping scientists understand how ancient ancestry and social customs shape present-day health risks. The findings could improve genetic screening and lead to better, more personalized healthcare for people in India and for South Asian communities worldwide.
