The earliest settlers' antiquity and evolutionary history of Indian populations: evidence from M2 mtDNA lineage
Satish Kumar , PBSV Padmanabham, Rajasekhara R Ravuri, Kiran Uttaravalli, Padmaja Koneru, P Aditi Mukherjee, B Das, M Kotal , D Xaviour , SY Saheb and VR Rao
Anthropological Survey of India, 27 Jawaharlal Nehru Road, Kolkata 700 016, India
BMC Evolutionary Biology 2008,
The "out of Africa" model postulating single "southern route"
dispersal posits arrival of "Anatomically Modern Human" to Indian
subcontinent around 66–70 thousand years before present (kyBP). However
the contributions and legacy of these earliest settlers in contemporary
Indian populations, owing to the complex past population dynamics and
later migrations has been an issue of controversy. The high frequency
of mitochondrial lineage "M2" consistent with its greater age and
distribution suggests that it may represent the phylogenetic signature
of earliest settlers. Accordingly, we attempted to re-evaluate the
impact and contribution of earliest settlers in shaping the genetic
diversity and structure of contemporary Indian populations; using our
newly sequenced 72 and 4 published complete mitochondrial genomes of
The M2 lineage, harbouring two deep rooting subclades M2a and M2b
encompasses approximately one tenth of the mtDNA pool of studied
tribes. The phylogeographic spread and diversity indices of M2 and its
subclades among the tribes of different geographic regions and
linguistic phyla were investigated in detail. Further the reconstructed
demographic history of M2 lineage as a surrogate of earliest settlers'
component revealed that the demographic events with pronounced regional
variations had played pivotal role in shaping the complex net of
populations phylogenetic relationship in Indian subcontinent.
Our results suggest that tribes of southern and eastern region along
with Dravidian and Austro-Asiatic speakers of central India are the
modern representatives of earliest settlers of subcontinent. The Last
Glacial Maximum aridity and post LGM population growth mechanised some
sort of homogeneity and redistribution of earliest settlers' component
in India. The demic diffusion of agriculture and associated
technologies around 3 kyBP, which might have marginalized
hunter-gatherer, is coincidental with the decline of earliest settlers'
population during this period.