A new paper published in the Proceedings of the National Academy of Sciences (subscription required) offers a counter theory to the long held Aryan Invasion Theory (thanks for the tip “Gujjubhai” and “Mauritious”). But before I get into that, I want to address a pet peeve of mine. The word “theory” is one of the most mis-used words in the English language. When most people use the word theory, they actually mean to use “hypothesis” or “hunch.” A theory by definition means:

A set of statements or principles devised to explain a group of facts or phenomena, especially one that has been repeatedly tested or is widely accepted and can be used to make predictions about natural phenomena.

By definition a theory has already stood up to repeated challenges, and on the basis of scientific evidence has held true despite many assaults on its validity. Therefore the Theory of Evolution isn’t just some willy-nilly hunch. It has taken on and turned aside all would-be challengers. Everybody “knows” that gravity is real, but did you know that Newton’s gravity is in fact a theory? When dealing with physics that approach the speed of light, the Newtonian Theory of Gravity fails, and Einstein’s Theory of Relativity takes over. Now that we are past that let’s go back to the PNAS paper. First, what is the “Aryan Invasion Theory”:

a term that refers to the theory developed by 19th Century European linguists to explain the similarity between Sanskrit and European languages, by hypothesising that peoples originating outside India invaded or migrated to India. Another view is that this theory was developed as a means to show the superiority of European Aryan race. Max Muller and other western scholars who studied Sanskrit were very impressed with it and wanted to develop a link of this brilliant language with there own race i.e Europeans. They found some roots common in german and sanskrit and invented AIT. There is no archaeological evidence for the invasion. In ancient times there were abundant contact between civilization in India and Europe and European languages borrowed lot of words/roots from Sanskrit. Interesting fact is that modern non-Indians still cling to this theory even though it has no locus standi or a scientific basis. [Link]

You see? Even the great Wikipedia perpetuates the inaccuracy. The so-called “Aryan Invasion Theory” has no archaeological evidence supporting it. Therefore, it should have been called the “Aryan Invasion Hunch.” The PNAS paper however forwards a real theory based on actual scientific evidence which throws cold water on the Aryan Invasion Hunch:

Understanding the genetic origins and demographic history of Indian populations is important both for questions concerning the early settlement of Eurasia and more recent events, including the appearance of Indo-Aryan languages and settled agriculture in the subcontinent. Although there is general agreement that Indian caste and tribal populations share a common late Pleistocene maternal ancestry in India, some studies of the Y-chromosome markers have suggested a recent, substantial incursion from Central or West Eurasia. To investigate the origin of paternal lineages of Indian populations, 936 Y chromosomes, representing 32 tribal and 45 caste groups from all four major linguistic groups of India, were analyzed for 38 single-nucleotide polymorphic markers. Phylogeography of the major Y-chromosomal haplogroups in India, genetic distance, and admixture analyses all indicate that the recent external contribution to Dravidian- and Hindi-speaking caste groups has been low. The sharing of some Y-chromosomal haplogroups between Indian and Central Asian populations is most parsimoniously explained by a deep, common ancestry between the two regions, with diffusion of some Indian-specific lineages northward. The Y-chromosomal data consistently suggest a largely South Asian origin for Indian caste communities and therefore argue against any major influx, from regions north and west of India, of people associated either with the development of agriculture or the spread of the Indo-Aryan language family. The dyadic Y-chromosome composition of Tibeto-Burman speakers of India, however, can be attributed to a recent demographic process, which appears to have absorbed and overlain populations who previously spoke Austro-Asiatic languages. [Link]

Is there a Razib in the house? For you non-science types here is an article from National Geographic for the layman.

Most modern Indians descended from South Asians, not invading Central Asian steppe dwellers, a new genetic study reports.

The Indian subcontinent may have acquired agricultural techniques and languages—but it absorbed few genes—from the west, said Vijendra Kashyap, director of India’s National Institute of Biologicals in Noida… The finding disputes a long-held theory that a large invasion of central Asians, traveling through a northwest Indian corridor, shaped the language, culture, and gene pool of many modern Indians within the past 10,000 years…

Testing a sample of men from 32 tribal and 45 caste groups throughout India, Kashyap’s team examined 936 Y chromosomes. (The chromosome determines gender; males carry it, but women do not.)

The data reveal that the large majority of modern Indians descended from South Asian ancestors who lived on the Indian subcontinent before an influx of agricultural techniques from the north and west arrived some 10,000 years ago…

Kashyap and his colleagues say their findings may explain the prevalence of Indo-European languages, such as Hindi and Bengali, in northern India and their relative absence in the south.

“The fact the Indo-European speakers are predominantly found in northern parts of the subcontinent may be because they were in direct contact with the Indo-European migrants, where they could have a stronger influence on the native populations to adopt their language and other cultural entities,” Kashyap said. [Link]

Very interesting stuff. Despite the close contacts with Aryan populations, this evidence suggestes that South Asians and Aryans didn’t “get it on” nearly as much as some people thought they did.

If steppe-dwelling Central Asians did lend language and technology, but not many genes, to northern India, the region may have changed far less over the centuries than previously believed.

“I think if you could get into a time machine and visit northern India 10,000 years ago, you’d see people … similar to the people there today,” Underhill said. “They wouldn’t be similar to people from Bangalore [in the south].”

The larger relevance of this issue is that it was the most contentious point in the debate over corrections to California textbooks that I blogged about earlier. It seems the Hindu groups who slammed Harvard Sanskrit scholar Michael Witzel now have some formidable ammunition on their side:

One of the most contentious issues the Hindu groups and Witzel and his supporters locked horns over was whether there was any truth to the Aryan invasion theory, which maintains that a group of people from Central Asia who called themselves Aryans invaded India around 1,500 B.C., and that Hinduism grew out of the beliefs and practices of the Aryans. Witzel and his group support the theory; the Hindu groups do not. The Hindu groups say that more recent archeological and DNA findings debunk the theory and suggest that the Aryans were an indigenous people who did not invade. Moreover, say the Hindu groups, plenty of linguistic and other evidence indicates that Hinduism existed in India long before 1,500 B.C.

At a special meeting held by the Board of Education on Jan. 6, to which Witzel and Prof. Shiva Bajpai, whose views the Hindu groups support, were invited, a compromise was hammered out and accepted by both sides. The textbooks would reflect both views, and the word “invasion” would be replaced by migration. [Link]