In the US Southwest and Mexican Northwest, tens of thousands of people were on the move in the 1200s through 1400s CE. By the end of the 1400s, regional-scale population levels had declined by about 50%. What conditions led to this pulse of migration and depopulation? Here we show, through a Southwest/Northwest scale meta-analysis of sub-regional archaeological studies, the spatial distribution, intensity, and variation in social and environmental conditions within eight culture areas, prior to depopulation. We find that as these conditions, identified as human insecurities by the UN Development Programme, worsened, the speed of depopulation increased. Results presented affirm the relationships that inspire and inform the human security framework and associated policies: as insecurities increased, migration increased, and the sustainability of places decreased. Population decline was not the result of a single disturbance, such as drought, to the regional system; it was a spatially patterned, multi-generational decline in human security. A mechanism for the progressive north to south regional scale rather than limited northern sub-regional depopulation is a contagion of migration-induced human insecurity.
Note: unlike most Tree-Ring Talks, this one does not have a permanent recording of the slideshow and video.