via Science Open, 30 December 2020: Recent paper about changes in rice agriculture in China and dry rice agriculture helped spread rice in Southeast Asia.
Archaeobotanical research in East and Southeast Asia provides evidence for transitions between lower and higher productivity forms of rice. These shifts in productivity are argued to help explain patterns in the domestication process and the rise of urban societies in these regions. The domestication process, which is now documented as having taken a few millennia, and coming to an end between 6700 and 5900 bp, involved several well documented changes, all of which served to increase the yield of rice harvests by an estimated 366 per cent; this increase provides an in-built pull factor for domestication. Once domesticated, rice diversified into higher productivity, labour-demanding wet rice and lower-yield dry rice. While wet rice in the Lower Yangtze region of China provided a basis for increasing population density and social hierarchy, it was the development of less productive and less demanding dry rice that helped to propel the migrations of farmers and the spread of rice agriculture across South China and Southeast Asia. Later intensification in Southeast Asia, a shift back to wet rice, was a necessary factor for increasing hierarchy and urbanisation in regions such as Thailand.