Abstract

The Atacama Desert is an extreme environment that has undergone significant changes in available moisture throughout the late Quaternary. Many paleorecords show that areas in the high Andes and western precordillera have experienced significant increases in rainfall, likely the result of intensified summer systems associated with the South American Summer Monsoon, tropical Pacific sea-surface temperature gradients and the mean position of the Intertropical Convergence Zone. These past “pluvials” generated increased runoff, elevated groundwater tables throughout the region, and had far-reaching impacts from the Andes to the Pacific coast. Here we summarize our recent research from four different examples of how these changes in climate bear on cultural evolution in the Atacama. Abundant evidence now exists for an early colonization of even the Atacama’s hyperarid core. First, dated between 12-13 ka (103 calibrated 14C years BP) most of these sites have extraordinary well-preserved evidence for how this region was settled and the hydrological resources available. Second, increased groundwater supplies and abundant marine resources along the coast of northern Chile likely augmented Chinchorro hunter-gatherer populations to the extent that this may help explain their advanced technology and artificial mummification techniques. Third, increases in groundwater associated with minor pluvials during the late Holocene at 2.5- 2.1 and 1.2-0.7 ka are coeval with major population expansion and development of “hydraulic societies”. Finally, a recent long-term trend in aridity may explain the demise of Aymara populations in the precordillera of northernmost Chile.