A Remarkable Exploration of South Asia 50,000 Years Ago and the Recently Revealed Story of Two Extinct Human Species.
A new study reveals that the genetic makeup of modern Indians is inherited from ancestors in the region now known as Tajikistan, as well as from both extinct human species: Neanderthals and Denisovans.
To uncover this, a research team from the University of California, Berkeley (UCB), Harvard University, the University of Michigan, the University of Pennsylvania, the University of Southern California (USA), the All India Institute of Medical Sciences, and the Finnish Institute for Molecular Medicine analyzed over 2,700 genomes of modern Indians.
Indian DNA contains rich data on human migration and evolution history – (Photo: LIVE SCIENCE).
The participants were selected from 17 states across various geographic regions, representing diverse ethnic groups to capture the genetic richness of a country with a population of 1.4 billion.
They also participated in a large national survey program called “Longitudinal Aging Study of India – Dementia Assessment” (LASI-DAD).
According to Associate Professor Priya Moorjani, a geneticist specializing in evolution and development at UCB, most Indians inherit from three ancestral groups: ancient Iranian farmers, Eurasian steppe herders, and South Asian hunter-gatherers.
Initially, the study aimed to investigate the origins of the first ancestral group, which had not been decoded by previous research. The results showed that before settling in Iran, they came from the land of Tajikistan.
However, a more significant surprise came from a separate analysis comparing the genomes of modern Indians with both extinct human species, Neanderthals and Denisovans.
These two species belong to the genus Homo, alongside our species, Homo sapiens. Interbreeding occurred in evolutionary history between many groups of each species, evidenced by the presence of a small amount of archaic DNA in our genomes.
The findings indicate that modern Indians carry 1%-2% of DNA from both of these ancient human species, with an astonishing richness. Nearly 90% of the known Neanderthal genes outside Africa are found in modern Indian individuals.
Complex relationships also reveal a major migration from Africa around 50,000 years ago; however, it remains unclear how the DNA of Homo sapiens mixed with that of Neanderthals and Denisovans along that journey, as well as the specific routes they took.
It is possible that these ancient human species existed in South Asia before the arrival of Homo sapiens, leading to interbreeding.
They may also have encountered each other along migration routes and in their “homeland” in Africa—perhaps multiple times—causing the DNA of Homo sapiens in India to mix with various populations of Neanderthals and Denisovans.
This new discovery promises to be a foundation for further findings that may reshape our understanding of human history.
