Movement of early humans into the Indian subcontinent
Tata Institute of Fundamental Research
Prehistoric human migration was mainly driven by human wanderlust and population pressures but relied critically on the habitability of available land. We have modelled such prehistoric population dynamics using a diffusion equation whose numerical solution is tempered by accurate geological data for the Indian subcontinent taken from satellite databases.
We define the driving forces by assuming that people will move out of any given region if the neighbouring regions are habitable. In turn, we define habitability by quantifying parameters like the availability and proximity of water, and flatness and altitude of the land. We define relative habitability which takes into account the presence of the initial population. We then consult the archaeological evidence of early humans in the subcontinent and identify three possible locations in Kabul which would represent the Ancestral North Indian entry into India, Hyderabad which would represent the earliest Ancestral South Indian population into India and we take two possible entry points for Ancestral Austro Asiatic as Goa and Orissa identified as two major break points in the mountain range that mark the Indian Subcontinent for people coming to India along the coast.
We find that people entering from Goa would soon become indistinguishable from the original Ancestral South Indian population. We therefore focus on entry from Orissa. On simulating the movement of these people we find that the groups merge in well localised geographical regions within the subcontinent. We then analyse the genetic data of the tribal population of the region. Since these groups are largely endogamous, they maintain their original genetic signal with very weak dilution due to intermixing. This allows us to identify the roots of different groups and compare it with our simulation. The genetic data agrees well with our predictions. We then expand our simulation to show that over a long period of time, the pattern of population that appears, agrees well with the present population of India.
Image shows one stage in the movement of people into the hinterland of the Indian subcontinent starting from Kabul, Hyderabad and North Orissa. Credit: Vahia, Yadav, Ladiwala, Mathur