UCLA

This article examines large-scale spatial and temporal patterns in the agricultural demographic transition (ADT) of Mesoamerica and southwestern North America (“the Southwest”). An analysis of published settlement and subsistence data suggests that the prolonged ADTs of these regions involved two successive eras of rapid population growth. Although both periods of growth were fueled by the introduction or development of more productive domesticates, they had distinctive demographic and social consequences. The first phase of the ADT occurred only in a scattering of favorable regions, between 1900 and 1000 BC in Mesoamerica and 1200 BC–AD 400 in the Southwest. Its demographic consequences were modest because it was underwritten by still rather unproductive maize. During this phase, increased population was confined mainly to a few agricultural heartlands, whereas surrounding regions remained sparsely populated. The second phase of the ADT was more dramatic in the spatial scale of its impact. This “high productivity” phase unfolded between 1000 and 200 BC in Mesoamerica and AD 500–1300 in the Southwest, and it was fueled by more productive maize varieties and improving agricultural technologies. It was accompanied by sweeping social, economic, and political changes in both regions.