Abstract

The antiquity and radiocarbon chronology of the first human settlements of South America is one of the most widely debated topics in American archaeology. Issues include points of entry, dispersal mechanisms and the process of initial human settlement that then diversified into regional cultural processes. The immigration paths taken, including the coastal or inland routes, as well as the cultural diversity present in these early settlements are also heavily disputed. Despite evidence for the earliest occupations of South America as old as 14.6 ka, there is a notable absence of dates >11 ka along the coast of southern Peru as well as in the central Atacama. Here, we propose that extensive areas in the foreboding Atacama Desert have been overlooked regarding their potential for harboring such early sites. Spanning over 1500 km, the hyperarid core of the Atacama Desert is truly one of the driest places on Earth. Paleoecological, stratigraphical and geomorphological evidence, however, indicate that portions of this desert contained in-stream wetlands and/or riparian woodlands between 17 to 11 ka, coeval with extensive wet phases across the central Andes. Increased summer rainfall over the regional highlands became manifest in the lower desert as increased runoff and heightened groundwater tables and the extensive aggradation of fluvial terraces covered with vegetation. Such resources would have been ideal areas for early settlements. One particular such settlement was recently uncovered by our research team at site Quebrada Mani 12 (S21.09°; W69.43°; 900 m). Six radiocarbon dates on charcoal excavated from one test pit containing bifaces and other lithic artifacts span from 14.5 to 11.8 ka. These ages indicate that site QM12 is perhaps one of the oldest known archaeological sites from northern Chile. Our study also reveals the vast untapped potential of this region for finding even more such early sites by linking archaeological surveys to regional paleoenvironmental change.