Dendrochronological dates confirm a Late Prehistoric population decline in the American Southwest derived from radiocarbon dates

Abstract

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 America is unknown owing to the lack of high-resolution palaeodemographic data from regions across and beyond the greater Southwest, where archaeological radiocarbon data are often the only available proxy for investigating these palaeodemographic processes. Radiocarbon time series across and beyond the greater Southwest suggest widespread population collapses from AD 1300 to 1600. However, radiocarbon data have potential biases caused by variable radiocarbon sample preservation, sample collection and the nonlinearity 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 compare those proxies to radiocarbon time series. We develop a new method for time series analysis 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 to 1600. These results lend confidence to single proxy radiocarbon-based reconstructions of palaeodemography outside the Southwest that suggest post-AD 1300 population declines in many parts of North America. This article is part of the theme issue ‘Cross-disciplinary approaches to prehistoric demography’.

Archaeology, demography and life history theory together can help us explain past and present population patterns

“…For example, as Arroyo-Kalin & Riris [30] put it in their study of regional population patterns in Amazonia, 'simply put, the size of human populations bears on how novel human niches are formed, how traditions of material culture evolve, why people intensify food production, and how new languages diversify within a language family'. Of importance in a different way, Robinson et al [34] show that the correspondence between radiocarbon and dendrochronological patterns in an area where both are available, validates the use of summed radiocarbon probabilities as a demographic indicator of population collapse in areas where these are the only available data source. The paper by Timpson et al [35], together with the associated software, represents the latest methodological development in the statistical analysis of summed radiocarbon probability distributions, by identifying the maximum number of change points in a population trajectory that can be justifiably inferred from the information in a given dataset, and the dates at which they occurred, using a continuous piecewise linear model.…”

Human securities, sustainability, and migration in the ancient U.S. Southwest and Mexican Northwest

“…Population levels began to decline throughout the SW/NW around 1300 CE (Dean et al 1994, Doelle 2000, Robinson et al 2021. Prior to the decline, population levels in the U.S. Southwest rose for at least a millennium, peaking between 100,000 and 160,000 people around 1000 CE (Dean et al 1994, Doelle 2000.…”

“…1) developed diverse lifeways and a repertoire of social and environmental dryland strategies (Ortiz 1979, Ingram and Hunt 2015, Cordell and McBrinn 2012. This multi-millennial trajectory of variable population growth ended during the early 1300s CE, and by the late 1400s, well before Spanish contact, population levels in the region declined by about one-half (Dean et al 1994, Doelle 2000, Robinson et al 2021. In some places within the region, the proximate causes of the decline are fairly well documented, such as environmental challenges to food security (Gumerman 1988) and changing climate patterns (Dean 1996).…”

Isotopic Evidence for Long-Distance Connections of the AD Thirteenth-Century Promontory Caves Occupants

“…Whatever the cultural identities involved, the Promontory record raises an important and broader set of issues. The AD thirteenth century in western North America was turbulent, featuring profound social and environmental shifts in which hunter-gatherer mobility imparted significant advantages for some groups as more sedentary societies vanished (as with Fremont) or retracted (as with Puebloan communities; e.g., Benson et al 2007; Kohler et al 2014; Robinson et al 2021). By the time of Spanish contact, there existed a variety of Plains-Puebloan interactions founded on the trade of Plains bison and other products for Puebloan goods, and a spectrum of relationships ranging from enclavement among Puebloan communities (as with the Jicarilla Apache) to raiding (Eiselt 2012).…”