Comment on Arnold et al. “Drought and the collapse of the Tiwanaku Civilization: New evidence from Lake Orurillo, Peru” [Quat. Sci. Rev. 251 (2021): 106693]

Abstract

This paper revives a fascinating debate: did a drought start before, during, or after the collapse of the Andean polity of Tiwanaku? Here we present an alternate age model that highlights the real issue: the data from Lake Orurillo, no matter the age model, are too imprecise to address the question. The authors neglect the significance of four-century error ranges (95% probability) for a drought that lasted a single century, according to their estimates. They are content to treat an imprecise correlation between drought and collapse as a causal relationship. Future efforts will require much greater attention to refining both paleoclimate and cultural chronologies, which is a necessary first step in understanding complex episodes of human–environment interaction.