Migration and Paleomobility in the Face of Environmental Change and Political Collapse: Case Studies from San Pedro de Atacama, Northern Chile

In the South Central Andes, the transition between the Middle Horizon (~CE 500–1100) and Late Intermediate Periods (~CE 1100–1400) is characterized by political collapse as well as environmental change, including a severe drought. Here, we investigate migration and paleomobility during this tumultuous time in the San Pedro de Atacama oases of northern Chile. We present an isotopic identification of the geographic origins of numerous individuals buried in San Pedro de Atacama cemeteries during both the Middle Horizon and the subsequent Late Intermediate Period, utilizing radiogenic strontium and stable oxygen isotope data from archaeological human remains. Overall, we argue that the San Pedro de Atacama oases appear to be have been inhabited by culturally and biologically diverse groups in addition to the predominant local population and does not seem to indicate the migration of large numbers of colonists from the Tiwanaku capital and surrounding Lake Titicaca Basin. Moreover, following the collapse of the Tiwanaku polity, a more homogeneous population with less evidence of migration characterizes the Late Intermediate Period in the San Pedro de Atacama oases. We argue that detailed and long-term studies of migration and paleomobility can provide a unique perspective on the role of migration during times of environmental change and political collapse.