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.

Maria Bruno is a professor of Anthropology and Archaeology at Dickinson College.

For more information on the published version, visit Science Direct's Website. https://www.sciencedirect.com/science/article/abs/pii/S0277379121002110

Marsh, Erik J., Daniel Contreras, Maria C. Bruno, Alexei Vranich, and Andrew P. Roddick. Comment on Arnold et al.Drought and th Collapse of the Tiwanaku Civilization: New Evidence fro Lake Orurillo, Peru[Quat. Sci. Rev. 251 (2021): 106693]. Quaternary Science Reviews 269 (2021): 107004. https://www.sciencedirect.com/science/article/abs/pii/S0277379121002110

Citation