Human organizational change and climate variability in northwest Patagonia: the last 1000 years BP using a multi-proxy approach

GIL, ADOLFO; NEME, GUSTAVO; OTAOLA, CLARA; SUGRAÑES, NURIA; SALGÁN, MARÍA LAURA; DAVAURNÉ, ARMANDO; PERALTA, EVA; LÓPEZ, JOSÉ MANUEL; GIARDINA, MIGUEL; POMPEI, MARÍA DE LA PAZ; FRANCHETTI, FERNANDO

Dublin

Otro; International Union For Quaternary Research 2019; 2019

This poster explores the archaeological record in relation with climate variation during the last 1000 years. Using a paleocimatic reconstruction of SAM (Southern Annular Mode) we compare human demography, diet, and technological organization.In order to evaluate how stable or variable was the human organization in Northwest Patagonia we explore multi proxies that indicate aspect of human population dynamic, subsistence, diet, mobility and exchange/spatial. We calculated the summed probability distributions of the calibrated radiocarbon dates (SPD) using RCarbon. We build the radiocarbon SPD using different spatial scale, northwest Patagonia (South Mendoza) and secondly Monte and Patagonia subset of the first area.The reconstruction of SAM is characterized by a period with predominance of the positive phase of SAM from the beginning of the record (1000 years AP) until about early 15th century (600 years BP). After that, the negative phase persistently prevails until the end of the 16th century (ca. 350 years BP), reaching extreme values around 500 years BP. The persistence of the positive phase of SAM during the first centuries of the last millennium implies the occurrence of late spring-early summer temperatures above the long-term mean in the southern sector of Mendoza. On the contrary, the more negative values of the SAM, prevailing in the 15th and 16th centuries (500 to 350 years BP), can be associated with an interval with dominant below-average temperature across the region.All these findings point out that the last millennium, in Northwest Patagonia was not a stable socio-ecological system. We detect abrupt changes associated with an increase in human demography and a significant increase in primary productivity as consequence of SAM negative modulation that generated summers with more precipitation and cooler than normal. This scenario of population growth in Patagonian hunter gatherers could cause their expansion to the North, retracting the limits of prehispanic farming, just a few centuries before the Spanish arrived.