Sep 25 2009
New Genetic Analysis Sheds Light on Origins of Indian Castes
For as long as humans have lived in complex communities, cities and civilizations, they have divided and classified their societies. Those divisions have been based on age, gender, appearance or – in many cases – occupation. In many traditional societies artisans would share the same social status; as would soldiers, priests and workers in any number of other occupations.
In antiquity, the status of a family rarely changed. If you were a farmer, your sons would be farmers, and so on. While today social status barriers are crumbling in many societies, in others they remain largely unchanged.
India’s complex social stratification, known as the caste system, has been one of the traditional cornerstones of society. Though urban Indians are shedding the caste labels of their parents and grandparents, many rural Indians – who make up 72% of the entire population – hold steadfast to the system. In small villages and towns, the Brahmin caste – consisting of scholars and priests – is still revered as one of the highest social strata. And members of the Dalit caste – formerly known as “Untouchables” – are still viewed as unclean and remain separated from others.
The rigidity of the system still present in rural India has made many wonder exactly how long castes have existed. Historical records are unclear, as early Hindu scriptures like the Bhagavad Gita are somewhat ambiguous when it comes to the topic. Some historians even propose that the caste system as we know it today is largely a construct of the English Colonial Era, arguing that the development of such a system could have been deemed necessary to instill order.
Genetic analysis has also proven inconclusive, as analysis of small segments of the human genome has yielded different results. But a new study by geneticist David Reich and colleagues, published in the September 24 issue of Nature, takes a new approach to understanding the genetic history of India.
The core difference between Reich’s genetic analysis and previous studies is in the sheer amount of genetic material analyzed. Reich’s team examined more than 550,000 points across all segments of the human genome. In doing so, they hoped to obtain a more complete picture of Indian genetic history.
The research team analyzed the DNA of 132 individuals from India and neighboring regions, dividing them into 25 distinct groups based on geography, caste and language. They calculated how genetically ‘closed’ each of these groups were. In the caste system it is rare to marry someone from another class, making caste societies very closed, or ‘endogamous.’ If this endogamy continues over many generations, it will leave a behind a genetic signature for scientists to discover.
Reich and his team found such a signature, indicating a long history of endogamy in several of the groups. In fact, the research team calculated that the DNA of six of the groups can be traced back to just a few individuals who lived anywhere from 30 to more than 100 generations ago. Assuming a generation time of 25 years, that establishes the existence of the caste system in the range of 750 to more than 2,500 years ago — long before the British colonial era.
In a second analysis, Reich and his team examined how ancient migrations could have influenced the formation of castes. First the researchers divided the Indian groups into language families: Indo-European and Dravidian. Dravidian tongues, like Tamil and Malayalam, are mainly spoken in southern India and are believed to be a remnant of languages spoken by some of the earliest inhabitants of the region. Indo-European languages, like Punjabi and Urdu, are more common in the north. They are believed to have arrived with a migration of farmers from southwestern Asia or the Near East about 9,000 years ago.
Reich and his colleagues then compared the genetics of each of the Dravidian and Indo-European groups to a sample of European DNA. The team reasoned that, if Indo-European groups were really descended from the farmers, they would show more genetic similarity to the Europeans than the Dravidians.
Not surprisingly, the authors’ hypothesis held true. The Indo-European speakers, like the Kashmiri Pandit and Vaish, were more genetically similar to Europeans. And because the majority of the upper castes speak Indo-European languages, while the lower ones tend to be Dravidian speakers, there could be a relationship between the arrival of Indo-European people and the formation of caste structure. Further evidence that an ancient caste system has permeated through India for thousands of years.
Regarding what is stated in the last paragraph, “And because the majority of the upper castes speak Indo-European languages, while the lower ones tend to be Dravidian speakers”..
..The vast majority of Indians, are Indo-European speakers regardless of caste. This essentially points to the fact that a pre-Indo European population adopted the culture and language of these Indo-European warrior-herders who later became the twice born/dvija OR upper caste Hindus.
What was exclusive to upper caste Hindus until a while ago was the privilege of Sanskrit and Vedic learning. It was only the Brahmins, Kshatriyas and Vaishyas, the Aryan twice born castes who were historically allowed to carry out their own Homa, chant the Gayatri Mantra (an invocation of sorts) and being admitted to Ashramas, where they were thought the Vedas, Upanishads and other sacred texts alongside training in physical pursuits by credible teachers, mainly sages.
Varna as in, Dharmashastra is unique to the Indo-Europeans of South Asia. So essentially, Aryans, as a people in Hindu society are those of high castes alone.The twice born castes initially divided themselves into specific castes and professions based on the characteristics of cosmic energy. These Aryans divided themselves based on their qualities. Thus, the intelligent and spiritually oriented became the Brahmins, the chivalrious and strong became Kshatriyas (warriors) and the skillful and industrious became Vaishyas (traders).
Regardless everyone in India is mixed to a certain extent, since the area was historically a melting pot of several races. Nothing is beyond human nature, not even a form of stratification that makes endogamy a system, can stop humans from mixing. However, most data points to the Upper Castes being the least mixed, alongside having an overwhelming West-Eurasian (“Caucasoid”) predominance.
As an aside, it is highly unfortunate that 23andMe doesn’t deliver to India, considering that Indians are an under studied population. You’re leaving out 1 Billion potential customers you know, which also bring about avenue for further, non-mainstream research as in projects like Dodecad, Eurogenes, etc.
Hi Vasishta,
Thanks for your comment. Regarding delivery to India, every country must go through legal and regulatory clearance before we can add it to the list of countries we can ship to. When we can add it, we will!
“the upper castes speak Indo-European languages, while the lower ones tend to be Dravidian speakers?” What nonsense! People of the same group, upper or lower castes, speaks the same language.