Mitochondrial DNA variation was studied in 100 Indians using the same set of six restriction enzymes used in the study of other world ethnic groups in order to compare and discern possible relationships of the Indian populations. Twenty nine mtDNA types were found including the ones from an earlier study (Semino et al. 1991) and unweighted pair-group method (UPGMA) and maximum parsimony trees were constructed using the mtDNA types. The nucleotide diversity values were calculated using the maximum likelihood method. From a study of the shared mitochondrial DNA types and the parsimony tree (Fig. 2) we came to the conclusion that the Indian population is closer to Caucasians and has an admixture with Asians. The North Indian population appears to have a recent admixture of the Caucasian mtDNA types which is absent in the south.

SummaryThe population of the Indian subcontinent represents a very complex social and cultural structure. Occupying a geographically central position for the early modern human migrations, indications are that the founder group that migrated out of East Africa also reached India. In the present study we used the twin strategy of mapping the whole mitochondrial DNA (mtDNA) using the standard 14 restriction enzymes, and sequencing the non-transcribed HVSI region, to derive maximum maternal lineages from a sample of non-tribal Indians. The essential features of the reduced median network of the two datasets were the same. Both showed two demographic expansions of two major haplogroups, 'M' and 'N'. The reduced median network was drawn with inputs from other studies on the Indian population, and correlated with data from other ethnic populations. The coalescence time of expansions and genetic diversity were estimated.A reduced median network was also drawn combining data from studies on Africans, Southeast Asians and WestEurasians, tracing the migration of 'M' from East Africa to India. A time estimate of the migration of major mtDNA haplogroups from Africa was attempted. The comparison of a set of Indian maternal lineages belonging to different geographical regions of the country, with other populations revealed the in-situ differentiation and antiquity of the Indian population. Our analysis places the 'southern route' migration as the source of haplogroup 'M'. Multiple migrations might have brought the other major haplogroups, 'N' and 'R', found in our sample to India. Archaeological evidence of modern humans in the subcontinent supports this mtDNA study.

Recent studies on human mtDNA have identified continent-specific restriction enzyme sites and resultant haplo-groups among populations from different regions of the world. Such studies have helped in elaborating the models for human migrations. We have studied Indian mtDNAs to identify the recognized world ethnic elements present in it. The results presented here are based on the study of DdeI 10394 site along with the associated Asian-specific AluI 10397 site in the mtDNA sequences of the Indian samples. On examining all the related haplo-groups, this study suggests that the apparent affinities of Indians and East Asians (comprising Chinese, Japanese, Southeast Asians etc.) could be due to a proto-Asiatic element present in Indians.

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