HUMAN ORGANIZATIONAL CHANGE AND CLIMATE VARIABILITY IN NORTHWEST PATAGONIA: THE LAST 1000 YEARS BP USING A MULTI-PROXY APPROACH

GIL, ADOLFO; NEME, G.; OTAOLA, C.; SUGRAÑES, N; SALGÁN, M.L.; DAUVERNÉ, A.; PERALTA, E; LOPEZ, JM; GIARDINA, M.; POMPEI, M.P; FRANCHETTI, F.

Dublin

Congreso; INQUA; 2019

Oxford University

Although Northwest Patagonia was inhabited by hunter-gatherer until historic times with evidence of ?farming islands? in the north sector (mostly Diamante and Atuel River). Until the recent time, the human evolutionary trajectory had been focused in a coarse-grained temporal resolution, using multi-millennial units. This presentation explores the archaeological record in relation to climate variation during the last 1000 years. Using a paleoclimatic reconstruction of SAM (Southern Annular Mode) we compare human demography, diet, and technological organization. Different proxies indicate two different scenarios. First, between 1000 to 1300 years AD, dominated by SAM positive, hotter and driest summers were associated with stable human population, low use of high-rank resources, like guanaco, and low frequency of non-local rock and ceramics. Around 1400 years AD, start to dominate SAM negative, that implied cooler summer associated with an increase in precipitation. An abrupt increase in the human population was observed in a period of ca. 200 years (ca. 1400 to 1600 AD). In addition, a notable increase in guanaco exploitation and significant change on stable isotopes trend on the human bone (13C and 15N) indicate a change in diet. An increase in a non-local rock like obsidian and non-local ceramic are recorded too. Clearly, these changes were operating before LIA and before the Hispanic domination (recorded ca. 1800/1880 AD in the area, ca. 1550 in a macro-region). All these findings point out that the last millennium, in Northwest Patagonia was not a stable socio-ecological system. Contrarily, we detect abrupt changes associated with an increase in human demography and a significant increase in primary productivity as a 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.