Genetically, as good as chalk and cheese

North-south divide

That all life is related by common ancestry, and that populations change form over time, constitute the bases of human evolution. And yet recent research now reveals that the great North-South divide existed even in pre-historic India, at least genetically.

So far, sociologists and historians have made much of the differences between inhabitants of northern and southern India. Now, after analysing thousands of tiny genes, scientists have identified two distinct genetic traits separating north and south
Indians almost 45,000 years ago, predating history.  

Because of their distinctive signatures, ancient north and south Indians are genetically as different as chalk and cheese. Today, nearly all Indians carry genomic contributions from these two distinct ancestral populations.

Ancient south Indians evolved almost 65,000 years ago when one of the direct descendent of the first human being on the planet – Onges of Andaman – settled on the islands. South Indians – much ancient compared to the north Indians – are genetically similar to the Onge tribal who retain some of the pristine genes from the first ever human being on the planet.

The ancient north Indians branched out from modern European population almost 45,000 years ago. They are genetically similar to West Asians, Central Asians and Europeans, a group of researchers have claimed in a scholarly paper published in the peer reviewed journal Nature that will appear on Thursday. “Their genes are 40 to 80 per cent similar to that of Europeans,” K Thangaraj, one of the team members at the Centre for Cellular and Molecular Biology (CCMB), Hyderabad told Deccan Herald.

The finding suggests that much before the Indus Valley civilisation and the so-called Aryan invasion, north Indians had ancestors who were genetically close to modern-day Europeans. Indian history has recorded detailed information about the Harappans and provided sketchy ideas on the Stone and Bronze ages.

But history is mostly blank beyond 8,000 years. Comparing 10 lakh pieces of Indian genes with European and Chinese genes, scientists from India and the USA inferred that two genetically distinct population branches existed 45,000 years ago.

Thangaraj said the findings do not support the “Aryans-bringing-foreign-genes-to-India” theory since thousands of years before the Aryans there were people in India with distinctive traits.

“This is a significant revelation which shows the variation of Indian genome, “ Council for Scientific and Industrial Research Director General Samir K Brahmachari said.

The researchers from CCMB, Harvard Medical School and Harvard School of Public Health analysed genes taken from the whole genome of 132 individuals from 25 diverse groups, representing 13 states, six language families, traditionally “upper” and “lower” castes, and tribal groups.

The finding that nearly all Indian groups descend from mixtures of two ancestral populations applies to traditional “tribes” as well as “castes”.  The findings suggest castes are inseparable from tribes. Genetics proves that they are not systematically different. Castes grew directly out of tribal-like organisations during the formation of Indian society.

Social practices like marriage within the same caste helped preserve unique genetic signatures that aided the researchers in understanding India’s population history.
However, everybody is not convinced with the north-south divide theory. “It’s not that simplistic. There may be many more such settlements,” RM Pitchappan, an independent geneticist from Madurai Kamraj University said. “I will take the conclusions with a pinch of salt,” Pitchappan said.

Distinctive features

* Scientists identify two distinct genetic traits separating north and south Indians
* South Indians are much ancient compared to the north Indians
* North Indian genes are 40 to 80 per cent similar to that of Europeans
* Before Aryans, there were people in India with distinctive traits

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