Hyderabad: A group of city scientists in collaboration with international researchers on Thursday debunked the age-old Aryan theory that states that Aryans are the progenitors of north Indian population. It also sets aside the Dravidian theory that north Indian and south Indian people are genetically different.
The present-day north Indian and south Indian populations are a genetic mixture of what could be called the ancestral south Indian population and the ancestral north Indian population. The north Indian ancestral group is closely related to European populations unlike the south Indian ancestral group, which is distinctly unique.
Ancestral south Indian population and ancestral north Indian population had married among each other to give raise to the present Indian population, which is neither Dravidian nor Aryan. "It is a genetic mixture of ASI and ANI and is quite distinct from the original ancestral groups," points out K Thangaraj, senior scientists at the city-based Centre for Cellular and Molecular Biology.
The pioneering research study, conducted jointly by the CCMB, Harvard Medical School, Harvard School of Public Health and the Broad Institute of Harvard and MIT, USA, is being claimed as the one "which will rewrite the Indian anthropological and genetics history".
According to the study, nearly all Indians carry genomic contributions from two distinct ancestral populations. Following this ancient mixture, many groups experienced periods of genetic isolation from each other for thousands of years. It has medical implications for people of Indian descent.
Although the genome sequences of any two unrelated people differ by just 0.1 per cent that tiny slice of genetic material is a rich source of information. It provides clues that can help reconstruct the historical origins of modern populations. The research team analysed more than 5,00,000 genetic markers across the genomes of 132 individuals from 25 diverse groups, representing 13 States, all six language families, traditionally "upper" and "lower" castes, and tribal groups.
Dr Lalji Singh, co-author of the study, said India is not a nation of one population. It is a nation of 4635 populations, 532 tribes and 72 primitive tribes. The original tribal population gave birth to the caste system as it diverted from forest life to agricultural activity. Caste system in India dates back to thousands of years and it is not a creation of the British, as is commonly believed.
The researchers also found that Indian populations were much more highly subdivided than European populations. But whereas European ancestry is mostly carved up by geography, Indian segregation was driven largely by caste. "There are populations that have lived in the same town and same village for thousands of years without exchanging genes," says co-author David Reich of Harvard Medical School.