Climate change underlies global demographic, genetic, and cultural transitions in pre-Columbian southern Peru

Abstract

he role of transient or long-term climatic changes and resulting environmental impacts on human dispersals and demographic development is generally accepted (1, 2). Nevertheless, the exact mechanisms underlying such changes and the extent of their influence on local population histories of prehistoric humans remain poorly understood. Pre-Columbian Andean cultures can offer exceptional insights into such human–environment interactions. In fact, western South America underwent several climate changes following the Pleistocene–Holocene transition since the initial peopling ∼14,000 y ago (3, 4). The frequency of climatic changes seems to have been accelerated with the establishment of modern atmospheric conditions and increasing variability of the El Niño Southern Oscillation around the end of the Mid-Holocene (4, 5), resulting in multiple transient and protracted environmental impacts on the Central Andean region (6, 7). Several studies have pointed at the temporal coincidence of occasional environmental and catastrophic events (7, 8) and long-term climatic alterations (5, 9) with episodes of cultural transition and changes of socioeconomic structure throughout the pre-Columbian period, suggesting that climate has played a major role in the formation of the cultural and demographic complexity of the Central Andean area (5, 7, 8, 10). Adaptive responses of the Andean populations to environmental impacts (e.g., droughts) such as the intensification of irrigation and extensive terracing have been directly inferred from the archaeological record (7, 8, 10–12). However, www.pnas.org/cgi/doi/10.1073/pnas.1403466111