Eastward dispersal from Southwest Asia was slower than that unto Europe
A new study, published in the open-access journal PLoS One, has considered the eastwards spread of agriculture from Southwest Asia. This has been less well studied than the westwards expansion into Anatolia and Europe.
Researchers conducted a statistical analysis of radiocarbon dates for 160 Neolithic sites in western and southern Asia. The locations of these sites suggest that the dispersal of farmers eastwards from the Zagros followed two routes: a northern route via northern Iran, southern Central Asia and Afghanistan, and a southern route via Fars through the interior of southern Iran.
Analysis of the radiocarbon dates indicated an eastwards expansion at an average speed of 0.65 km per year, rather slower than the 1 km per year documented for Europe. The authors of report considered this to be unsurprising. Firstly, the arid climate and complicated topography of the region are less favourable for agriculture. Because of this, the early Neolithic settlements in Iran were relatively small and widely separated. Secondly, the European expansion was aided by the Danube, the Rhine and the Mediterranean coastline, but there are no major rivers in Afghanistan or Iran that could play a similar role.
The authors were encouraged that the fairly simple ‘wave of advance’ model used captured the salient features of the data studied, but stressed the need for a more detailed analysis that would consider local environments and climatic conditions.
1. Gangal, K., Sarson, G. & Shukurov, A., The Near-Eastern Roots of the Neolithic in South Asia. PLoS One 19 (5), e95714 (2014).