Abstract. In A.D. 1200 the Four Corners area of the American Southwest was a thriving, bustling center, yet 100 years later it was completely depopulated. Archaeologists have been wondering at this depopulation since the first Euro-American explorers found the abandoned cliff dwellings of the Ancestral Pueblo people in the late 1800s. While traditional archaeological methods have told us much about the Ancestral Pueblo people, the ultimate reasons for the depopulation of this region still remain elusive.
However, complex adaptive systems approaches can shed light on the multifaceted reasons that Ancestral Pueblo people ultimately decided to abandon the Mesa Verde homeland. In this talk I demonstrate how food web analysis and agent-based modeling can help us understand the 700-year occupation of the Four Corners, and factors that led up to its abandonment. Key to decisions to leave the region were cascading effects of resource over use, leading to decreased resilience of the environment. High human density coupled with a maize-centric food system in an environment that was particularly susceptible to prolonged droughts created a perfect storm that required new innovations—or migration—to survive.