Fundamental genomic unity of ethnic India is revealed by analysis of mitochondrial DNA

Mitochondrial DNA (mtDNA) profiles of 23 ethnic populations of India drawn from diverse cultural, li n-guistic and geographical backgrounds are presented. There is exten sive sharing of a small number of mtDNA haplotypes, reconstructed on the basis of r es-triction fragment length polymorphisms, among the populations. This indicates that Indian populations were founded by a small number of females, possibly arriving on one of the early waves of out-of-Africa migration of modern humans; ethnic differentiationern Chinaoccurred subsequently through demographic expan-sions and geographic dispersal. The Asian-specific haplogroup M is in high frequency in most popula-tions, especially tribal populations and Dravidian pop u lations of southern India. Populations in which the frequencies of haplogroup M are relatively lower show higher frequencies of haplogroup U ; such pop u-lations are primarily caste popu lations of northern India. This finding is indica tive of a higher Caucasoid admixture in northern Indian populations. By exami n-ing the sharing of haplotypes between Indian and south -east Asian populations, we have provided evi-dence that south -east Asia was pe opled by two waves of migration, one originating in India and the other originating in southern China. These findings have been examined and interpreted in the light of infer-ences derived from previous genomic and historical stu d ies. I