Human-araucaria interactions during the Holocene in northwest Patagonia, Argentina

Araucaria araucana has long had an important role in the subsistence and cultural practices of aboriginal groups on both sides of the Andes in Southern South America. Despite its relevance, systematic studies on past human interactions with this species, which is limited to the Pehuén Forest, are lacking. This study examines the spatial pattern of A. araucana use in Northwest Patagonia from the Early Holocene to historic times, comparing it with the current and Holocene potential distribution of the Pehuén Forest. We analysed the presence of macro and microbotanical remains in archaeological sites and stable isotopes from human bones. The earliest evidence of its use dates to ~7000 years BP aligning with the postglacial expansion of the species. Archaeological records predominantly consist of macroremains of seeds, primarily in sites near the Late-Holocene maximum potential extent of the Pehuén Forest. Isotope-based consumption probabilities confirm these results showing a high contribution of araucaria to the human diet in areas adjacent to the forest. For the later Late-Holocene the use of araucaria extends more than 300 km from the Pehuén Forest, as is revealed by the finding of starch grains in grinding tools and ceramics. Additionally, the use of A. araucana increased from 1000 years BP onwards in association with a rise in human population density and, probably, with changes in subsistence and technology. This research highlights the complex and dynamic interaction between prehistoric human populations and A. araucana trees throughout the Holocene.