Caste barriers not older than 2000 years - Indians mated across ethnic groups till 2nd century: Study (The Telegraph (Calcutta))
“People across India mixed and mated without class, caste, or ethnic barriers for about 2,300 years until strict endogamy emerged across the subcontinent around the 2nd century AD, a new genetic study has suggested.
“The study by scientists at the Centre for Cellular and Molecular Biology (CCMB), Hyderabad, and the Harvard Medical School has indicated a staggering level of population admixture that they say had not been previously suspected.
“The scientists said that ancient, pervasive and widespread mixture of genes showed up in the genetic makeup of virtually all of India’s present-day populations — upper-castes, lower-castes, and even tribes such as Bhils of Gujarat, the Kallars of Tamil Nadu, and another tribe from Uttar Pradesh, long viewed as genetically isolated.
“The study, based on the analysis of the genetic make-up of 571 persons from 73 well-defined ethno-linguistic groups — 71 from India and two from Pakistan — has found evidence of widespread population mixture between 4,200 and 1,900 years ago.
“‘With the dawn of endogamy, genetic mixing became rare — that’s what we see in present-day Indian genomes,’ Priya Moorjani, a graduate student at the Harvard Medical School and the first author of the study, told The Telegraph. The findings will be published tomorrow in the American Journal of Human Genetics.”
Genetic Research Suggests Indian Caste System Began 1,900 Years Ago (Slate, August 20, 2013):
“But when did the caste system actually begin? One team of researchers believes the country’s genetic history holds the key. In a recent paper published in the American Journal of Human Genetics, researchers from Harvard, MIT, and the CSIR-Centre for Cellular and Molecular Biology in Hyderabad assembled what they call the ‘most comprehensive sampling of Indian genetic variation to date,’ using samples collected from 571 individuals belonging to 73 ‘well-defined ethno-linguistic groups.’ The data allowed the authors to trace not just the genetic mixture between these groups but how long ago this mixture occurred.
“Five thousand years ago, the ancestors of modern Indians were comprised primarily of two groups: ancestral North Indians, who related to people of Central Asia, the Middle East, the Caucasus, and Europe, and ancestral South Indians, who are not closely related to groups outside the subcontinent. The mixture between these two groups and their many subcategories happened mostly between 4,200 and 1,900 years ago, according to the study. The authors note that this period is significant as it was a ‘time of profound change in India, characterized by the deurbanization of the Indus civilization, increasing population density in the central and downstream portions of the Gangetic system, shifts in burial practices, and the likely ﬁrst appearance of Indo-European languages and Vedic religion in the subcontinent.’
“Around 1,900 years ago, the mixture largely stopped, as Indian society moved toward endogamy—the practice of avoiding intermarriage or close relationships between ethnic groups—which reached its most extreme form in the creation of the caste system. As one of the study’s authors told the Times of India, ‘the present-day structure of the caste system came into being only relatively recently in Indian history.’”
But not cast(e) in stone (DNA (Mumbai), August 31, 2013):
“It seems the first set of modern humans to have migrated to the Indian subcontinent were the Andamanese 65,000 to 75,000 years ago. They then migrated to coastal areas in South India and mixed with Dravidian population groups. Scientists refer to these first inhabitants of India as Ancestral South Indians (ASI). The second wave of migration from Africa took place 40,000 to 45,000 years ago. During migration this group probably split into two — one inhabiting Europe and the other heading towards Middle East and then India.
“This group has been dubbed Ancestral North Indians (ANI). This explains why ASIs don’t show any genetic affinity to groups outside the Indian subcontinent and ANIs show 30 to 70 percent genetic affinity to West Asians, Middle Easterners, Europeans and Caucasians. Most Indian population groups descended from a mixture of these two genetically divergent populations — ASI and ANI. This study had major implications for Indian history because it clearly showed that the origin of genetic diversity found in South Asia is much older than 3,500 years when the Indo-Aryans were supposed to have migrated to India. This means, genetically speaking, there was no Aryan invasion at all.
“Now CCMB scientists have been able to put a date to admixture between ASI and ANI — crucial for a fuller understanding of Indian history. The admixture, according to findings of the study published by Dr Kumarasamy Thangaraj and colleagues this month, probably took place 1,900 to 4,200 years ago.
“The most remarkable aspect of the mixture is its pervasiveness. It affected not just traditionally upper-caste groups, but also traditionally lower-caste and isolated tribal groups such as Bhils or Palliyars, all of whom are united in their history of genetic mixture in the past few thousand years. The time-frame implies that India experienced a demographic transformation during this period — from being a region in which major population mixture was common to one in which mixture even between closely related groups became rare as reflected in a shift to endogamy (a key attribute of the caste system).
“The fact that Indians evolved from randomly mixed groups suggests that social classifications like the caste system did not exist in the same way before the mixture. In other words, the present-day structure of the caste system came into being only relatively recently. But once established, the caste system became genetically effective because mixture across groups became very rare. The Vysya community from Andhra Pradesh, which has experienced negligible gene flow from neighbouring groups for 3,000 years, is an illustrative example of this. Many population groups have evolved in genetic isolation during this period.”