Language and Farming Spread in India

Most maternal lineages of present-day Indians derive from a common ancestor in mtDNA haplogroup M that split into Indian, eastern Asian, Papuan, and Australian subsets 40,000-60,000 mtDNA-years ago. The second major component in Indian maternal heredity lines traces back to the split of haplogroup U into Indian, western Eurasian and northern African variants approximately at the same time. The variation in these two ancient Indian-specific sets of lineages is the main modifier in the heterogeneity landscape of Indian populations, defining the genetic differences between caste groups and geographic regions in the sub-continent. The difference between regional caste groups is accentuated furthermore by the presence of a northwest to south decline of a minor package of lineages of western Asian or European origin. In contrast, the majority of Indian paternal line-ages do not share recent ancestors with eastern Asian populations but stem from haplogroups common to (eastern) European or western Asian populations. This finding has recently been interpreted in favour of the classical Indo-Aryan invasion hypothesis. Here, we show that this interpretation is probably caused by a phylogeographically-limited view of the Indian Y-chromosome pool, amplified because of current inconsistencies in the interpretation of the temporal scale of the variability in the non-recombining part of the Y chromosome (NRY). It appears to us that the high variability of STRs in the background of NRY variants in India is consistent with the view of largely autochthonous pre-Holocene genetic diversification-a conclusion reached earlier for the Indian maternal lineages (Kivisild et al. 1999a). While interpreting the genetic aspects of farm-ing/language dispersal in the Indian context, it is easy to get lost in its 'multitude of endogamous pock-ets' (Cavalli-Sforza et al. 1994). Yet a forest can hopefully be seen behind the trees, provided that the conclusions to be drawn derive from a phylogeo-graphically representative analysis of the people of the sub-continent. Perhaps new ideas, analogous to the recently introduced 'SPIWA' model for Europe (see Renfrew this volume), are needed when developing new farmingl/anguage dispersal models for India. The earliest 'agricultural package' in the Indian subcontinent-a combined presence of wheat, barley , cattle, sheep and goat domestication-is found in Mehrgarh, Baluchistan, and dates to about 9000 years before present (BP). It spread first into an area extending from the Punjab in the northwest to Uttar Pradesh in the east and to Gujarat in the south. It took another 4000 years before it eventually reached southern Peninsular India …