When the rains stopped: Evapotranspiration and ontology at ancient cahokia

Climate change and human history converged in the ancient Mississippi Valley at the Native American city of Greater Cahokia. Following the materials and substantial flows through four centuries of the Medieval Climate Optimum (ca. 900–1300 ce) leads to the recognition that evapotranspiration—as experienced in the American Midwest and institutionalized as “Steam Bath Ceremonialism”—was central to the formation and demise of Cahokian urbanism. The transubstantiation of water into steam transferred spiritual, healing power to people. That transfer was undermined with the droughty periods beginning in the 1100s. The close correspondence between human and other-than-human historical changes in this Mississippian case supports explanations of hydrosocial change that begin in the ontological realm.