Bioavailable Strontium, Human Paleogeography, and Migrations in the Southern Andes: A Machine Learning and GIS Approach

BARBERENA, RAMIRO; CARDILLO, MARCELO; LUCERO, GUSTAVO; LE ROUX, PETRUS J.; TESSONE, AUGUSTO; LLANO, CARINA; GASCO, ALEJANDRA; MARSH, ERIK J.; NUEVO-DELAUNAY, AMALIA; NOVELLINO, PAULA; FRIGOLÉ, CECILIA; WINOCUR, DIEGO; BENÍTEZ, ANAHÍ; CORNEJO, LUIS; FALABELLA, FERNANDA; SANHUEZA, LORENA; SANTANA SAGREDO, FRANCISCA; TRONCOSO, ANDRÉS; CORTEGOSO, VALERIA; DURÁN, VÍCTOR A.; MÉNDEZ, CÉSAR

Frontiers in Ecology and Evolution

Frontiers

Año: 2021 vol. 9 p. 1 - 20

The Andes are a unique geological and biogeographic feature of South America. Fromthe perspective of human geography, this mountain range provides ready access tohighly diverse altitudinally arranged ecosystems. The combination of a geologically andecologically diverse landscape provides an exceptional context to explore the potentialof strontium isotopes to track the movements of people and the conveyance of materialculture. Here we develop an isotopic landscape of bioavailable strontium (87Sr/86Sr)that is applied to reconstruct human paleogeography across time in the southern Andesof Argentina and Chile (31?34S). These results come from a macro-regional samplingof rodents (N = 65) and plants (N = 26) from modern and archeological contexts.This ?Southern Andean Strontium Transect? extends over 350 km across the Andes,encompassing the main geological provinces between the Pacific coast (Chile) and theeastern lowlands (Argentina). We follow a recently developed approach to isoscapeconstruction based on Random Forest regression and GIS analysis. Our results suggestthat bioavailable strontium is tightly linked with bedrock geology and offers a highlyresolved proxy to track human paleogeography involving the levels of territories ordaily mobility and anomalous events that disrupt home ranges, such as migration.