Genetics and archaeogenetics of South Asia
The study of the genetics and archaeogenetics of the ethnic groups of South Asia aims at uncovering these groups' genetic history. The geographic position of India makes Indian populations important for the study of the early dispersal of all human populations on the Eurasian continent.According to the phylogeographic distribution of haplotypes observed among South Asian populations defined by social and linguistic criteria, the possibility arose of Y-DNA haplogroup F and mtDNA Haplogroup M might have originated in South Asia. The presence of several subclusters of F-M89 and K that are largely restricted to the Indian subcontinent is consistent with the scenario that a coastal (southern route) of early human migration out of Africa carried ancestral Eurasian lineages first to the coast of the Indian subcontinent, or that some of them originated there. Studies based on mtDNA variation have reported genetic unity across various Indian sub–populations. Conclusions of studies based on Y Chromosome variation and Autosomal DNA variation have been varied, although many researchers argue that most of the ancestral nodes of the phylogenetic tree of all the mtDNA types originated in the subcontinent. Recent genome studies appear to show evidence in support of the notion that modern south Asians (both Indo-Aryans and Dravidians) are a hybrid population descending from two genetically divergent populations referred to as the 'Ancestral North Indians' related to western eurasians and the 'Ancestral South Indians' who are not closely related to groups outside the subcontinent. It has been found that the ancestral node of the phylogenetic tree of all the mtDNA types typically found in Central Asia, the Middle East and Europe are also to be found in South Asia at relatively high frequencies. The inferred divergence of this common ancestral node is estimated to have occurred slightly less than 50,000 years ago. In India the major maternal lineages, or mitochondrial DNA Haplogroups, are M, R and U, whose coalescence times have been approximated to 50,000 BP.All major Y chromosome DNA haplogroups in the subcontinent are Haplogroup F's descendant haplogroups R (mostly R2a, R2 and R1a1), L, H and J (mostly J2). Many researchers have argued that Y-DNA Haplogroup R1a1 (M17) is of autochthonous Indian origin. However, proposals for a Central Asian origin for R1a1 are also quite common.