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

• Published in: Proceedings of the National Academy of Sciences - PNAS Vol. 111; no. 26; pp. 9443 - 9448
• Main Authors: Schmitz, Lars, Haak, Wolfgang, Mächtle, Bertil, Masch, Florian, Llamas, Bastien, Cagigao, Elsa Tomasto, Sossna, Volker, Schittek, Karsten, Cuadrado, Johny Isla, Eitel, Bernhard, Reindel, Markus
• Format: Journal Article
• Language: English
• Published: United States National Academy of Sciences 01-07-2014; National Acad Sciences
• Subjects: Archaeology - methods; Base Sequence; Bayes Theorem; Bayesian analysis; Biological Sciences; Climate change; Climate Change - history; Climate models; Computer Simulation; Cultural Evolution - history; Culture; Demographics; Demography; DNA; DNA, Mitochondrial - isolation & purification; Droughts - history; Haplotypes; Haplotypes - genetics; Highlands; History, 15th Century; History, Ancient; History, Medieval; Human Migration - history; Humans; Migration; Mitochondrial DNA; Models, Genetic; Molecular Sequence Data; Paleoclimatology; Peru; Population Dynamics - history; Population genetics; Population migration; Precolumbian era; Sequence Analysis, DNA; Simulation; Social Sciences; Andes region; Peru; ISE, Peru; South America, Andes Mts; South America; ancient DNA; population history
• ISSN: 0027-8424; 1091-6490
• DOI: 10.1073/pnas.1403466111

Several archaeological studies in the Central Andes have pointed at the temporal coincidence of climatic fluctuations (both long- and short-term) and episodes of cultural transition and changes of socioeconomic structures throughout the pre-Columbian period. Although most scholars explain the connection between environmental and cultural changes by the impact of climatic alterations on the capacities of the ecosystems inhabited by pre-Columbian cultures, direct evidence for assumed demographic consequences is missing so far. In this study, we address directly the impact of climatic changes on the spatial population dynamics of the Central Andes. We use a large dataset of pre-Columbian mitochondrial DNA sequences from the northern Rio Grande de Nasca drainage (RGND) in southern Peru, dating from ∼840 BC to 1450 AD. Alternative demographic scenarios are tested using Bayesian serial coalescent simulations in an approximate Bayesian computational framework. Our results indicate migrations from the lower coastal valleys of southern Peru into the Andean highlands coincident with increasing climate variability at the end of the Nasca culture at ∼640 AD. We also find support for a back-migration from the highlands to the coast coincident with droughts in the southeastern Andean highlands and improvement of climatic conditions on the coast after the decline of the Wari and Tiwanaku empires (∼1200 AD), leading to a genetic homogenization in the RGND and probably southern Peru as a whole.