The results of GIS-based analyses of least-cost routes predicts that entry into Asia during OIS 4 is more likely to have used a coastal corridor that originated to the west, as opposed to a northern montane corridor through the Hindu Kush Mountains. Once in South Asia, populations may have followed a number of routes, which included both coastal and terrestrial contexts. Diversions into the interior are suggested via the Indus River and Narmada River valleys, and also through a break in the Western Ghats. The analyses also indicate that dispersals along the coasts of South Asia would have eventually turned inland at the Ganges–Brahmaputra Delta, and that this feature may have blocked or slow populations attempting to move eastwards.
What is known for the paleoenvironment of South Asia suggests that both the coasts and the interior would have been attractive to mobile parties of modern hunter-gatherers. If the use of coasts and riparian corridors allowed for rapid dispersals into South Asia, and movement between these environments was not a problem in terms of subsistence and subsistence related technologies, our analyses suggest that populations could have expanded rapidly into the heartland of South Asia. [...] This hypothesis has further support from genetic data that suggests lineage divergence in South Asia ca. 44,000–63,000 years ago, as well as archaeological evidence for increasingly modern behaviors in South Asia after this time period.
Journal of Anthropological Archaeology (Article in Press)
The southern dispersal hypothesis and the South Asian archaeological record: Examination of dispersal routes through GIS analysis
Julie S. Field et al
This research advances a model for coastal-based dispersals into South Asia during oxygen isotope stage (OIS) 4. A series of GIS-based analyses are included that assess the potential for expansions into the interior of South Asia, and these results are compared with known archaeological signatures from that time period. The results suggest that modern Homo sapiens could have traversed both the interior and coastlines using a number of routes, and colonized South Asia relatively rapidly. Use of these routes also implies a scenario in which modern H. sapiens, by either increased population growth or competitive ability, may have replaced indigenous South Asian hominin populations.