All Indians Are Genetically Linked

Hyderabad: The great Indian divide along north-south lines now stands blurred with a pathbreaking study by Harvard and indigenous researchers on ancestral Indian populations stating that there is a genetic relationship between all Indians. What is more, this cutting edge research — that reconstructs the Indian population history — turns on its head the hitherto believed ‘fact’ that Aryans and Dravidians signified the ancestry of Indians from north and south respectively.

   “This paper rewrites history... there is no north-south divide,’’ said Lalji Singh, former director, Centre for Cellular and Molecular Biology (CCMB), and a co-author of the study, at a press conference here on Thursday.

   Senior CCMB scientist Kumarasamy Thangarajan said there was no truth in the Aryan-Dravidian theory as they came hundreds or thousands of years after our ancestors settled in the north and south of India.    The study analysed 500,000 genetic markers across the genomes of 132 individuals from 25 diverse groups from 13 states. All the individuals were from sixlanguage families and traditionally “upper’’ and “lower’’ castes and tribal groups. “The genetics proves that castes grew directly out of tribe-like organisations during the formation of the Indian society,’’ the study states. Thangarajan notes that it is impossible to distinguish between castes and tribes since their genetics proves they are not systematically different. The study was conducted by CCMB scientists in collaboration with researchers at Harvard Medical School, Harvard School of Public Health and the Broad Institute of Harvard and MIT.

Genetically One

Around 65,000 years ago, initial settlements began in Andamans & ancient south India.

Another 25,000 years later, the ancient north Indians emerged.

Eventually, north and south populations met, giving rise to a different set.

Present-day Indians are a mix of north and south, with genomic strains from two distinct ancestors — the Ancestral North Indian & Ancestral South Indian.

A mix of ancient north and ancient south

Hyderabad: A Harvard study on the north-south divide in the country reveals that the present day Indian population is a mix of ancient north and south bearing the genomic contributions from two distinct ancestral populations — the Ancestral North Indian (ANI) and the Ancestral South Indian (ASI).

   The study was conducted by CCMB scientists in collaboration with researchers at Harvard Medical School, Harvard School of Public Health and the Broad Institute of Harvard and MIT.

   “The initial settlement took place 65,000 years ago in the Andamans and in ancient south India at around the same time, which led to population growth in this part,’’ said Thangarajan. He added, “At a later stage, 40,000 years ago, the ancient Indians from the north emerged which in turn led to rise in numbers here. But at some point of time, the ancient north and the ancient south mixed giving birth to a different set of population. And that is the population which exists now and there is a genetic relationship between the population within India.’’

   The study also helps understand why the incidence of genetic diseases among Indians is different from the rest of the world. Lalji Singh, the co-author of the study, said that 70% of Indians were burdened with genetic disorders and the study could help answer why certain conditions have restricted themselves to one population. For instance, breast cancer among Parsi women, that of motor neuron diseases among residents of Tirupati and Chittoor, or sickle cell anaemia among certain tribes in central India and the North-East can now be understood better, say researchers.

   The researchers, who are now keen on exploring whether Eurasians descended from ANI, find in their study that ANIs are related to western Eurasians, while the ASIs do not share any similarity with any other populations across the world. However, researchers said there is no scientific proof of whether Indians went to Europe first or the other way round.

Migratory route of Africans   

The East-African droughts between 135,000 and 75,000 years ago, when the water volume of the lake Malawi was reduced by at least 95%, caused migration out of Africa. Which route did they take? Researchers say their study of the tribes of Andaman and Nicobar islands using complete mitochondrial DNA sequences and its comparison with the mitochondrial DNA sequences of world populations has led to the theory of a “southern coastal route’’ of migration from East Africa through India. This finding is against the prevailing view of a northern route of migration via Middle East, Europe, south-east Asia, Australia and then to India.