The demographic response to the introduction of rice agriculture in prehistoric Japan

The dispersal of rice farming in prehistoric Japan was characterised by a wide range of local responses. In some regions, farming dispersed swiftly, in others considerable delays have been observed. In other regions, cases of a temporary adoption followed by a return to a foraging economy have been noted.

In this paper, the demographic consequences of rice agriculture were investigated by estimating population growth rates and sizes using a range of computational and quantitative techniques. The researchers numerically accounted for the differences in the arrival time of farming in different parts of Japan and estimated the population trajectories of the first few centuries of the new subsistence economy.

The analyses show that while there are some short-term differences, after 750 years most regions showed similar trajectories, with an annual growth rate somewhere between 0.1 to 0.2%. There were, however, some notable exceptions, in particular in north-eastern Japan where changes in growth rate after the appearance of rice agriculture were not observed. 

This work builds on a previous paper where the team identified the rate of dispersal of agriculture in Japan and refined the arrival date of rice in different regions of the archipelago, highlighting where and to what extent the diffusion of rice farming was delayed.