Researchers report highly correlated environmental and population data suggesting climate shifts as a factor in the decline of Cahokia, a large prehistoric settlement in the United States. Multiple hypotheses have been proposed for the decline of Cahokia, a large prehistoric settlement that was located in Illinois, United States. Many hypotheses focus on possible social and environmental factors in the settlement's depopulation. Difficulty in correlating environmental conditions and population sizes has reduced confidence in such hypotheses. A.J. White and colleagues analyzed sediment cores from Horseshoe Lake, which is adjacent to the Cahokia settlement. The authors examined the cores' paleoenvironmental data, including oxygen stable isotopes, as well as fecal stanols, chemical signatures of human settlement that can be used as a proxy for population size and are highly correlated in time with paleoenvironmental data. The authors report that around 1150 CE the climate at Horseshoe Lake shifted toward decreased summer precipitation and the Mississippi River flooded, placing stress on Cahokia's agricultural system. Subsequent climatic changes and population decline suggest that the depopulation of Cahokia may have been influenced by the shift in climate accompanying the transition from the Medieval Climate Anomaly to the Little Ice Age. According to the authors, climatic factors should be considered alongside cultural and political factors in the decline of Cahokia.
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Article #18-09400: "Fecal stanols show simultaneous flooding and seasonal precipitation change correlate with Cahokia's population decline," by A.J. White et al.
MEDIA CONTACT: A.J. White, University of California, Berkeley, CA; tel: 949-521-0060; e-mail: < ajwhitesemail@gmail.com >
Proceedings of the National Academy of Sciences