A study, the most extensive DNA analysis of Indians till date, is overturning traditional understandings of the origins of the country’s various population groups. Undermining the impact of the Aryan invaders in shaping Indian civilisation, particularly the caste system, the study shows that the overwhelming majority of Indians are descended from two ancient populations, Ancestral South Indians (ASI) and Ancestral North Indians (ANI), who, respectively, came to the subcontinent 65,000 and 45,000 years ago.

This implies that although the country’s 1.2 billion people belong to about 4,600 religions, castes and linguistic communities, the population shares a deep genetic heritage. The study, published in the September 24 issue of Nature, was led by scientists at the Centre for Cellular and Molecular Biology (CCMB), Hyderabad, together with researchers at Harvard Medical School, the Harvard School of Public Health and the Broad Institute of Harvard and MIT, and has medical implications.

“The findings show us that there is no need to speak separately about Aryans and Dravidians. The politically sensitive question of the country’s North-South divide has been answered through this research,” said Dr Lalji Singh, former director, CCMB, and one of the authors of the Nature paper ‘Reconstructing Indian population history’. “(German philologist and Orientalist) Max Mueller first introduced the term Aryan. He applied the term to the Indo-European concept and identified this racial-linguistic entity as white. But our discovery contradicts this.”

Another finding is that the castes and tribes in the country are not systematically different. “(The study) supports the view that castes grew directly out of tribal-like organisations during the formation of Indian society,” said Kumarasamy Thangaraj, another CCMB scientist. Singh said the castes grew directly out of tribal set-ups during the formation of Indian society.

Some historians had argued that caste in modern India was an invention of colonialism in the sense that it became more rigid under colonial rule, but the “results indicate that many current distinctions among groups are ancient and that strong endogamy (matrimony within one’s own isolated group) must have shaped marriage patterns in India for thousands of years”.

About ASI and ANI, David Reich of the Harvard Medical School and a co-author of the paper said: “The ANI is genetically close to Middle Easterners, Central Asians, and Europeans, whereas the other, the ASI, is as distinct from ancestral north Indians and East Asians as they are from each other.

“Nobody’s even close to having all of one or the other… People in India are almost all a mixture of these two ancestral populations.”

The paper says: “ANI ancestry ranges from 39-71% in most Indian groups, and is higher in traditionally upper caste and Indo-European speakers. Groups with only ASI ancestry may no longer exist in mainland India. However, the indigenous Andaman Islanders are unique in being ASI-related groups without ANI ancestry.” The Andaman finding is in keeping with the CCMB’s report in 2005 that the tribes in the island were the descendants of the first humans moving out of Africa.

“(But) have Eurasians descended from the ANI? This is the question we would like to address in our future research activities,” Singh said.

The research team analysed more than five lakh genetic markers across the genomes of 132 individuals from 25 diverse groups in 13 states covering six language families. The sample group included upper and lower castes and tribal groups.

