Dendrochronological dates confirm a Late Prehistoric population decline in the American Southwest derived from radiocarbon dates
The northern American Southwest provides one of the most well-documented cases of human population growth and decline in the world. The geographic extent of this decline in North Amer- ica is unknown due to the lack of high-resolution palaeodemographic data from regions across and beyond the greater Southwest, where archaeological radiocarbon data is often the only avail- able proxy for investigating these palaeodemographic processes. Radiocarbon time series across and beyond the greater Southwest suggest widespread population collapses from AD 1300–1600. However, radiocarbon data have potential biases caused by variable radiocarbon sample preser- vation, sample collection, and the non-linearity of the radiocarbon calibration curve. In order to be confident in the wider trends seen in radiocarbon time series across and beyond the greater Southwest, here we focus on regions that have multiple palaeodemographic proxies and com- pare those proxies to radiocarbon time series. We develop a new method for time series anal- ysis and comparison between dendrochronological data and radiocarbon data. Results confirm a multiple proxy decline in human populations across the Upland US Southwest, Central Mesa Verde, and Northern Rio Grande from AD 1300–1600. These results lend confidence to single proxy radiocarbon-based reconstructions of paleodemography outside the Southwest that sug- gest post-AD 1300 population declines in many parts of North America.
