Deep common ancestry of Indian and western-Eurasian mitochondrial DNA lineages

About a fifth of the human gene pool belongs largely either to Indo-Europea n or Dravidic speaking people inhabiting the Indian peninsula. The 'Caucaso id share' in their gene pool is thought to be related predominantly to the Indo-European speakers. A commonly held hypothesis, albeit not the only one , suggests a massive Indo-Aryan invasion to India some 4,000 years ago [1]. Recent limited analysis of maternally inherited mitochondrial DNA (mtDNA) of Indian populations has been interpreted as supporting this concept [2,3] , Here, this interpretation is questioned. We found an extensive deep late Pleistocene genetic link between contemporary Europeans and Indians, provid ed by the mtDNA haplogroup U, which encompasses roughly a fifth of mtDNA li neages of both populations. Our estimate for this split is close to the sug gested time for the peopling of Asia and the first expansion of anatomicall y modern humans in Eurasia [4-8] and likely pre-dates their spread to Europ e. Only a small fraction of the 'Caucasoid-specific' mtDNA lineages found i n Indian populations can be ascribed to a relatively recent admixture.