Tribes of Andaman may have new human ancestor, say scientists

One of the interesting findings suggest that two tribal communities of the Andaman Islands, Jarawas and Onges, may have evolved from an unidentified human ancestor. The latest genetic analysis done by a joint team of Indian and Spanish scientists has suggested this. However, this claim is not yet supported by any fossil evidence but is sensational as it will add a fresh, unknown branch to human ancestry.

The discovery was made by scientists at the National Institute of Bio-Medical Genetics (NIBMG), Kalyani, West Bengal, in association with those from the Pompeu Fabra University, Barcelona, Spain. Scientists analyzed ten genetic samples derived from Jarawas and Onges in the Andamans along with 60 samples drawn from different ethnic groups across India. 

The finding is published in the scientific journal Nature Genetics.

Around 400,000 years ago, an ancestor of modern humans arose in Africa and migrated west towards Europe and east towards China and India. Those who went west evolved into the Neanderthals whereas those who migrated east developed into the Denisovans.

In the meantime, ancestral humans continued to evolve in Africa and about 50,000 years ago modern humans also started spreading out of Africa. Subsequently, they encountered earlier species like Neanderthals and Denisovans and interbred with them. All this shuffled up the genomes significantly but the modern technology can bring out the intermixing. The research team has done the same.

Besides, research by different scientists earlier showed that most people outside Africa derived 1 to 4% of their genetic material from Neanderthals, except in communities in Pacific Islands and Australian aborigines. They have up to 6% genetic contribution from Denisovans.

Furthermore, other aspects of the NIBMG's research show that the Andamanese are closer to Indians in their genetic makeup and likely came in the same wave of migration from Africa as others in the region. 

The study also mentioned that the short stature of the Jarawas and Onges is likely due to natural selection and not just because their founders were short.