The largest ever genome study of South Asian people has discovered a wide range of Neanderthal DNA sequences in modern Indian people. The findings raise the possibility of building a full Neanderthal genome from living humans, instead of relying on DNA from ancient remains.
All modern humans except African people retain an average of around 1 to 2 per cent of their genetic ancestry from archaic hominins, including Neanderthals and Denisovans. African people also get about 0.5 per cent of their DNA from Neanderthals on average, even though Neanderthals never lived on the continent.
Studies of ancient DNA have produced three Neanderthal genomes that are around 70 per cent complete. But such ancient DNA has degraded before analysis, so it would be better to reconstruct the genome of ancient humans from sequences that survive in modern people, says at the University of California, Berkeley.
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Skov and his colleagues analysed the genomes of nearly 2700 people born in 23 states in India. They included speakers of at least 26 different languages who belonged to diverse caste groups and were from both rural and urban areas.
The people in the study derived 1 to 2 per cent of their ancestry from archaic hominins, similar to other non-African populations. But the Neanderthal DNA included more than 90 per cent of known Neanderthal gene sequences, more than any modern population that has been studied before. Nearly 12 per cent of these sequences haven鈥檛 been found in any other region.
The study also reveals that most of the overall genetic variation in Indian people stems from a single major migration out of Africa that occurred around 50,000 years ago.
Archaeological finds have shown that some modern humans migrated out of Africa before this point, but these migrations contributed very little genetic ancestry to modern Indian people.
Most Indian people鈥檚 ancestry is derived from three groups related to ancient Iranian farmers, Eurasian Steppe pastoralists and South Asian hunter-gatherers, the research found.
From the DNA of study participants, the team was able to reconstruct nearly two thirds of the Neanderthal genome and nearly a quarter of the Denisovan genome.
A previous study based on DNA from 27,566 people in Iceland was only able to reconstruct 41 per cent of the Neanderthal genome, says Skov. 鈥淪o there are just more different puzzle pieces present in India, even though we looked at 10 times less individuals.鈥�
He says the amount of Neanderthal DNA that has been recovered from other regions of the world has begun to plateau, while that from India still has considerable untapped potential.
鈥淏ut if we will ever be able to reconstruct 100 per cent of the genome is another matter,鈥� says Skov. 鈥淧robably not, but we can for sure reconstruct more.鈥�
at the Australian National University in Canberra says this study adds over 26 million new genetic variations to the global catalogue, showing the importance of diversity in genomic studies. 鈥淭hey use these genomic data to show that India is likely to be inhabited since around 54,000 years ago, which is remarkable,鈥� he says.
bioRxiv
