Genes Confirm Origin of India's Castes
European legacy shows up in higher social groups
FRIDAY, May 18, 2001 (HealthDayNews) -- New genetic research supports the historical theory that the Hindu caste system of India was more the invention of Europeans than of Indians.
Those born into higher castes in India may be more related to Europeans, while lower castes may be more similar to Asians, the research finds.
"We've been working in India, asking questions about the origins of the caste system and tribal populations," says Dr. Michael Bamshad, an assistant professor at the University of Utah's Eccles Institute of Human Genetics in Salt Lake City. "We were also interested in the effects of social forces on biological variations."
The original Hindu caste system is said to have started when Indo-European nomadic groups called Aryans invaded India about 1500 B.C. Setting themselves up as priests, they divided the society they encountered into a four-part caste system -- Brahmans (priests and teachers), Kshatriyas (rulers and warriors), Vaisyas (merchants and traders) and Sudras (workers and peasants) who were born to serve the other three. There also are castes within castes; in all, there are more than 1,000.
Lowest in the social order are the Harijans or Untouchables. They did all the dirty work.
To see if they could tease out the genetic origins of the caste system, Bamshad and his colleagues drew blood from eight different populations in the lower, middle and upper castes. They then compared five different types of genetic data, Bamshad says. "Two of those types are inherited only from your mother -- called mitochondrial data -- and two of those types are from the Y chromosome, so they come only from the father."
The researchers compared the data to about "750 Africans, Asians and Europeans and then compared the affinities of the castes of different ranks with those continental groups," Bamshad says.
The genetic data from the mother shows "some evidence of European markers," Bamshad reports. The higher the caste, the "higher the frequency of those European markers," he says.
But genes passed on from the father show a more striking pattern. "When we looked at father markers, we see that the castes are more similar to Europeans than Asians, again with the upper classes being closer to Europeans than the lower classes," Bamshad says.
Though India's ancient caste system was legislated out of existence in the 1960s, it continues as part of the social fabric of the country.
The findings, which appear in the May issue of Genome Research, support the historical data showing that India was in part populated by people from Turkey, the Middle East, the Caucasus or Eastern Europe, Bamshad says.
"And it also suggests that those who migrated from Europe often left their descendents in the higher castes rather than the lower castes," Bamshad says. "The evidence from the Y chromosomes shows that it was the men who married into the upper castes, and it appears that more men than women moved into India, and that certainly is consistent with the concept of a marauding army."
Bamshad's research falls under the rubric of molecular anthropology, says Peter Underhill, senior research scientist in genetics at Stanford University. "The main thrust of this research project is to better understand the Indian population, where it came from, how it developed."
"This research, which attempts to correlate genetics with the historical record, provides good genetic evidence, and such correlations are reassuring," Underhill says. "What's particularly nice about this paper is that it doesn't emphasize one slice of the genome. It weaves in genetics from both men and women."
While Bamshad's research has no direct relevance, "it would be of some interest to medical genetic studies. It's another piece of the puzzle that might help scientists understand certain traits within the Indian population," Underhill says.
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