Study reveals origin of India’s caste system
The study was carried out by Harvard Medical School and the CSIR-Centre for Cellular and Molecular Biology (CCMB) in Hyderabad.
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India's caste system, says a new genetic
study, began about 2,000 years ago. The study adds that people from
different genetic populations — from the North and the South — began to
mix with each other about 4,200 years ago but that the mixing stopped
about 2,000 years ago.
The study was carried out by Harvard Medical School and the CSIR-Centre for Cellular and Molecular Biology (CCMB) in Hyderabad. David Reich, a professor of genetics at Harvard Medical School, said that the caste system in India has been around for a long time, but that it had certainly not begun right at the very beginning.
Reich's 2009 study, based on an analysis of 25 different Indian population groups, found that all populations in India showed evidence of a genetic mixing of two ancestral groups — the Ancestral North Indians (ANI), who are related to central Asians, middle easterners, caucasians, and Europeans ; and the Ancestral South Indians (ASI), who are primarily from the subcontinent.
In the beginning, when the ANI and ASI populations mixed, their chromosomal segments would have been very long. But when the two groups began to intermarry, the chromosomal segments would have broken up at one or two places per chromosome, per generation, thus recombining maternal and paternal genetic material.
The researchers, by measuring the lengths of the segments of ANI and ASI ancestry in Indian genomes, were thereby able to obtain precise estimates of when this population mixture occurred. They found that it started 4,200 years ago — the Indus Valley civilisation was waning then, and huge migrations were occurring across north India, which might have caused the intermarrying . It is suspected that before that, the two groups lived side by side for centuries without intermarrying.
The researchers said the mixing was thorough, with even isolated tribes showing ancestry from both groups.
Lalji Singh, a former researcher at CSIR-CCMB , said: "The fact that every population in India evolved from randomly mixed populations suggests that social classifications like the caste system are not likely to have existed in the same way before the mixture happened."
The intermarrying stopped about 2,000 years ago. The Manusmriti , forbidding intermarriage across castes, was written around 100 BC.
The researchers added that once the caste system was established, it became genetically effective, and mixing across groups became very rare.
The study was carried out by Harvard Medical School and the CSIR-Centre for Cellular and Molecular Biology (CCMB) in Hyderabad. David Reich, a professor of genetics at Harvard Medical School, said that the caste system in India has been around for a long time, but that it had certainly not begun right at the very beginning.
Reich's 2009 study, based on an analysis of 25 different Indian population groups, found that all populations in India showed evidence of a genetic mixing of two ancestral groups — the Ancestral North Indians (ANI), who are related to central Asians, middle easterners, caucasians, and Europeans ; and the Ancestral South Indians (ASI), who are primarily from the subcontinent.
In the beginning, when the ANI and ASI populations mixed, their chromosomal segments would have been very long. But when the two groups began to intermarry, the chromosomal segments would have broken up at one or two places per chromosome, per generation, thus recombining maternal and paternal genetic material.
The researchers, by measuring the lengths of the segments of ANI and ASI ancestry in Indian genomes, were thereby able to obtain precise estimates of when this population mixture occurred. They found that it started 4,200 years ago — the Indus Valley civilisation was waning then, and huge migrations were occurring across north India, which might have caused the intermarrying . It is suspected that before that, the two groups lived side by side for centuries without intermarrying.
The researchers said the mixing was thorough, with even isolated tribes showing ancestry from both groups.
Lalji Singh, a former researcher at CSIR-CCMB , said: "The fact that every population in India evolved from randomly mixed populations suggests that social classifications like the caste system are not likely to have existed in the same way before the mixture happened."
The intermarrying stopped about 2,000 years ago. The Manusmriti , forbidding intermarriage across castes, was written around 100 BC.
The researchers added that once the caste system was established, it became genetically effective, and mixing across groups became very rare.
