Hydroclimate variability influenced social interaction in the prehistoric American Southwest

Abstract

In agricultural societies, farmers rely on their social networks to absorb the impacts of droughts and floods by facilitating resource flows to affected settlements and population flows away from them. These benefits depend on how well one’s social network connects populations that experience different weather patterns. Here I use an empirical archaeological case study from the late pre-Hispanic period in the North American Southwest to examine the relationship between drought variability and human social networks over a 250 year period. I analyze 7.5 million artifacts collected from nearly 500 archaeological sites, and estimate how the flow of social information between sites varied as a function of distance and growing-season hydroclimate variability. Interaction between regions experiencing different oceanic and continental influences was often higher than would be expected by chance and distance alone, but the intensity of this influence changed over time. This work highlights the importance of distinguishing between different dynamic origins of hydroclimate variability when considering the social impacts of droughts and pluvials in the past and present.