in India." concluded that there is "an extensive deep late Pleistocene genetic link between contemporary Europeans and Indians" via the mitochondrial DNA, that is, DNA which is inherited from the mother. According to them, the two groups split at the time of the peopling of Asia and Eurasia and before modern humans entered Europe. Kivisild et al. (2000) note that "the sum of any recent (the last 15,000 years) western mtDNA gene flow to India comprises, in average, less than 10 percent of the contemporary Indian mtDNA lineages." and note that north and south Indians share a common maternal ancestry: Kivisild et al. (2003) further note that "these results show that Indian tribal and caste populations derive largely from the same genetic heritage of Pleistocene southern and western Asians and have received limited gene flow from external regions since the Holocene. "Ancestral North Indians" and "Ancestral South Indians" , in a collaborative effort between the Harvard Medical School and the Centre for Cellular and Molecular Biology (CCMB), examined the entire genomes worth 560,000 single nucleotide polymorphisms (SNPs), as compared to 420 SNPs in prior work. They also cross-compared them with the genomes of other regions available in the global genome database. Through this study, they were able to discern two genetic groups in the majority of populations in India, which they called "Ancestral North Indians" (ANI) and "Ancestral South Indians" (ASI). They found that the ANI genes are close to those of Middle Easterners, Central Asians and Europeans whereas the ASI genes are dissimilar to all other known populations outside India, though the indigenous Andamanese were determined to be the most closely related to the ASI population of any living group (albeit distinct from the ASI). These two distinct groups, which had split ca. 50,000 years ago, formed the basis for the present population of India. The two groups mixed between 1,900 and 4,200 years ago (2200 BCE – 100 CE), where-after a shift to endogamy took place and admixture became rare. Speaking to Fountain Ink, David Reich stated, "Prior to 4,200 years ago, there were unmixed groups in India. Sometime between 1,900 to 4,200 years ago, profound, pervasive convulsive mixture occurred, affecting every Indo-European and Dravidian group in India without exception." Reich pointed out that their work does not show that a substantial migration occurred during this time. , representing a collaboration between the Estonian Biocenter and CCMB, confirmed