Genetics and archaeogenetics of South Asia

Genetics and archaeogenetics of South Asia is the study of the genetics and archaeogenetics of the ethnic groups of South Asia. It aims at uncovering these groups' genetic histories. The geographic position of the Indian subcontinent makes its biodiversity important for the study of the early dispersal of anatomically modern humans across Asia.

Based on mitochondrial DNA (mtDNA) variations, genetic unity across various South Asian subpopulations have shown that most of the ancestral nodes of the phylogenetic tree of all the mtDNA types originated in the subcontinent. Conclusions of studies based on Y chromosome variation and autosomal DNA variation have been varied.

The genetic makeup of modern South Asians can be described as a combination of West Eurasian ancestries with divergent East Eurasian ancestries. The latter primarily include a proposed indigenous South Asian component (termed Ancient Ancestral South Indians, short "AASI") that is distantly related to the Andamanese peoples, as well as to East Asians and Aboriginal Australians, and further include additional, regionally variable East/Southeast Asians components.

The proposed AASI type ancestry is closest to the non-West Eurasian part, termed S-component, extracted from South Asian samples, especially those from the Irula tribe, and is generally found throughout all South Asian ethnic groups in varying degrees. The West Eurasian ancestry, specifically an Ancient Iranian-related component, forms the major source of the South Asian genetic makeup, and combined with varying degrees of AASI ancestry, formed the Indus Periphery Cline around ~5400–3700 BCE, which constitutes the main ancestral heritage of most modern South Asian groups. The Indus Periphery ancestry, around the 2nd millennium BCE, mixed with another West Eurasian wave, the incoming mostly male-mediated Yamnaya-Steppe component to form the Ancestral North Indians (ANI), while at the same time it contributed to the formation of Ancestral South Indians (ASI) by admixture with hunter-gatherers having higher proportions of AASI-related ancestry. The ANI-ASI gradient, as demonstrated by the higher proportion of ANI in traditionally upper caste and Indo-European speakers, that resulted because of the admixture between the ANI and the ASI after 2000 BCE at various proportions is termed as the Indian Cline. The East Asian ancestry component forms the major ancestry among Tibeto-Burmese and Khasian speakers, and is generally restricted to the Himalayan foothills and Northeast India, with substantial presence also in Munda-speaking groups, as well as in some populations of northern, central and eastern South Asia.