Out of India Theory - Genetic Anthropology

Genetic Anthropology

Unlike the Indo-European migration hypothesis, there is no clear genetic evidence for a prehistoric migration out of India. There is no evidence of widespread genetic displacement in Europe after the Paleolithic. And Hemphill (1998) finds "no support for any model that calls for the ultimate origins of north Bactrian oasis Oxus Civilization populations to be inhabitants of the Indus Valley."

The virtual absence of India-specific mtDNA haplogroups outside of India argues against a large scale population movement out of India. Tracing a possible "out of India" migration has therefore until recently focused upon Y-chromosome haplogroups. Concerning Y DNA, haplogroup R2 is characterized by genetic marker M124, and is rarely found outside India, Pakistan, Iran, and southern Central Asia. Outside of southern Eurasia, M124 was found at an unusually high frequency of 0.440 among the Kurmanji of Georgia, but at a much lower frequency of only 0.080 among the Kurmanji of Turkmenistan. The M124 frequency of 0.158 found among Chechens may be unrepresentative because it was derived from a sample size of only 19 Chechens. Outside of these populations and the Romani people, M124 is not found in Eastern Europe.

Mass movements of people to or from India that might be associated with the spread of Indo-European languages have tended to revolve around Y-chromosome haplogroup R1a1, which is identified with the M17 mutation. On the one hand, this Y lineage is found in higher levels amongst northern Indians and amongst higher castes, and is also found in modern populations in Central Asia and Eastern Europe. On the other hand, the pattern within India is not always so clear, with lower castes and southern populations also sometimes showing high levels, and in fact several studies have proposed that the deepest roots of this lineage may be in or near India.

The latest research conducted by Watkins et al. (2008) questions the use of uniparental markers such as the Y chromosome or mitochondrial DNA, neither of which is immune to the effects of natural selection; they also argue for the need to analyze autosomal polymorphisms in conjunction with Y-chromosomal and mitochondrial DNA in order to generate a more comprehensive picture of population genetic structure. The authors of the study write: "The historical record documents an influx of Vedic Indo-European-speaking immigrants into northwest India starting at least 3500 years ago. These immigrants spread southward and eastward into an existing agrarian society dominated by Dravidian speakers. With time, a more highly-structured patriarchal caste system developed ... our data are consistent with a model in which nomadic populations from northwest and central Eurasia intercalated over millennia into an already complex, genetically diverse set of subcontinental populations. As these populations grew, mixed, and expanded, a system of social stratification likely developed in situ, spreading to the Indo-Gangetic plain, and then southward over the Deccan plateau."

Reich et al. (2009) indicates that the modern Indian population is a result of admixture between Indo-European (ANI) and Dravidian (ASI) populations. The authors of the study write: "It is tempting to assume that the population ancestral to ANI and CEU spoke 'Proto-Indo-European', which has been reconstructed as ancestral to both Sanskrit and European languages, although we cannot be certain without a date for ANI–ASI mixture."

In a 2011 genetic study "confirmed the existence of a general principal component cline stretching from Europe to south India." They concluded that "the Indian populations are characterized by two major ancestry components, one of which is spread at comparable frequency and haplotype diversity in populations of South and West Asia and the Caucasus. The second component is more restricted to South Asia and accounts for more than 50% of the ancestry in Indian populations. Haplotype diversity associated with these South Asian ancestry components is significantly higher than that of the components dominating the West Eurasian ancestry palette. Modeling of the observed haplotype diversities suggests that both Indian ancestry components are older than the purported Indo-Aryan invasion 3,500 YBP".