Human resilience to Holocene climate changes inferred from rodent middens in drylands of northwestern Patagonia (Argentina)

摘要

We reconstruct the Holocene vegetation, climate, and archaeological history for drylands of northwestern Patagonia, Argentina, based on multiproxy analysis (plant macrofossil, pollen, and parasites) of rodent middens integrated with a database of C-14 dates associated with human occupations. The local scale corresponds to the Huenul paleoecological and archaeological locality, emplaced in north-western Patagonia (Neuquen Province, Argentina). The rodent midden record from the Huenul series reflects subtle vegetation changes driven by climatic variability at millennial timescale. Drier than present environmental conditions prevailed during the early Holocene (10,500-9400 cal yr BP), peaking during the mid-Holocene (9200-5500 cal yr BP), when wetter than present conditions established during the late Holocene (4400-2500 cal yr BP). These environmental and climatic dynamics agree with other paleoclimatic records from northern Patagonia, suggesting the winter precipitation dynamics related to the Southern Westerlies as a common driver. The diachronic distribution of anthropogenic radiocarbon dates from the western area of the South American Arid Diagonal between 32 degrees-40 degrees S conforms to a fitted exponential model of steady background population growth, not suggesting significant demographic changes that may have been the result of the impact of climate change. This record indicates that these human populations coped successfully with aridity, particularly during the mid-Holocene. These findings reinforce the need to integrate multi-scalar interdisciplinary analyses to assess the impact of climate change in human societies.