Between AD 1050 and 1150, the Mississippian Cahokians who occupied a large area centered on west-central Illinois and the Anasazi who occupied the region centered on the San Juan Basin experienced a cultural fluorescence. However, by AD 1150, the Anasazi had abandoned most greathouse communities in the San Juan Basin and Cahokia had undergone a massive decline in population. By AD 1300 the San Juan Basin, the southern Colorado Plateau, and the Cahokian region had been essentially abandoned. A possible cause of the temporal symmetry of the rise and fall of these two distant cultures is the subject of this presentation.
In this presentation tree-ring based reconstructions of precipitation and the Palmer Drought Severity Index (PDSI) will be compared with estimates of population change for both cultures and an argument presented that environmental (climate) change contributed to the observed trends in population. In particular, it will be shown that two megadroughts of large areal extent affected both cultures nearly simultaneously, thus contributing to their near-synchronous demise. The impact of drought on agriculture is considered to be the link between climate change and cultural response in both regions.
Reception to follow in Mendenhall 291 at 2:00 pm.
