Models of the Neolithic dispersal in Southern Asia

Abstract

The Fertile Crescent in the Near East is one of the independent sources of the Neolithic. Farming and pottery making spread across Europe from the Fertile Crescent from 9,000 to 6,000 years ago at an average rate of about 1 km/yr. The Neolithic in the Near East and the Indian subcontinent is far less explored in terms of absolute (14C) dates as compared to the European Neolithic. The Neolithic chronology in the Indian subcontinent is mainly established with comparative dating and few 14C dates are available from the region. Hence, though a strong causal connection between the Neolithic of the Near East and the Indus valley has been suggested, any detailed study has been challenging. The different nature of the archaeological and 14C dates and their uncertainties make it difficult to combine them in any quantitative analysis of the Neolithic. We overcome this by allocating different uncertainties and thus compile a comprehensive database of Early Neolithic dates in South Asia. Using the earliest Neolithic arrival time(s) for each site, the globally averaged Neolithic dispersal speed from the Near East to the Indian subcontinent is calculated to be U = 0.65 ± 0.1 km/yr. Further inspection of the data shows that the Neolithic sites were restricted to the Fertile Crescent until about 7,000 BCE, and only later spread along the northern and southern borders of modern Iran. Analysis identifies two distinct routes of the Neolithic dispersal, one from the northern Zagros and the other from the southern Zagros, with significantly different dispersal speeds (about 0.6 km/yr for the southern route and 2 km/yr for the northern route). Furthermore, when combined with the Indus sites, the data suggests that the Neolithic plausibly reached the Indian subcontinent from the Northern Zagros. The Neolithic of the Near East is studied further by using a two dimensional spatial diffusion model that incorporates palaeo-vegetation and topography data. Further expanding the scope of the diffusion model, the spread of incipient farming in the Indian subcontinent is studied. Depending on the environment, different staple food crops dominate in different regions (e.g. wheat in north-western India and rice in eastern India); and the model considers the spread of these different staple crops allowing for the altitude and water requirement for these crops.