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Understanding the causes of subsistence economic adaptation remains a critical topic in archaeology. Here we explore one potential causal phenomenon, climate change, to understand how shifting ecological conditions incentivized adaptation through subsistence economic intensification along the Central Andean coasts. To do so we couple 775 archaeological individuals that have dietary stable isotope data (collagen δ13C and δ15N, hydroxyapatite δ13C) with spatio-temporal core-based proxies of oceanic sea surface temperature and El Ni˜no Southern Oscillation frequency estimates. Using an ensemble machine learning model, we evaluate hypotheses that changes in ocean conditions resulting in decreased marine productivity correspond with isotopic signals of increasing terrestrial resource reliance over the past ~7000 years. Results support the hypotheses, and prior work, showing isotopic signatures of diet across the coastal Central Andes reflect greater incorporation of resources indicative of intensification during times when marine productivity was likely depressed. As near-shore marine productivity declined, people adapted in manners that may have both increased their resiliency to climate change and improved their overall subsistence returns, but at higher investment costs. The overall findings support theoretical intensification expectations, suggesting adaptation through intensification represents one of the key factors in understanding broader behavioral transformation in the face of climate change.
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Approximate Bayesian Computation evaluation of the interactive effects of climate change and subsistence economic intensification on pre-contact population dynamics in western North America
Past population change is connected to significant shifts in human behavior and experience including landscape manipulation, subsistence change, sedentism, technological change, material inequality and more. However, population change appears to result from a complex interplay of human-environment interactions that feedback on each other, influencing and simultaneously impacted by processes such as subsistence intensification and climate change. Here we explore complex system dynamics of population change using theoretical and Approximate Bayesian Computational modeling combined with the archaeological record of the past 4,000 years in the Colorado Plateau and Great Basin regions of western North America as case studies to identify causal relationships and the different manners in which climate change may have interplayed with subsistence economic intensification and population dynamics. Using standard distance metric evaluation on the performance of 1,000,000 simulations compared with reconstructed past population sizes in each region reveals how climate change impacting landscape productivity can influence carrying capacity and structure population growth such that, when populations reach carrying capacity (Malthusian ceilings), intensification in their subsistence economy can send feedbacks into the socioecological system spurring rapid, differential, population growth. Comparisons of the two regions highlights how varied socioecological circumstances can produce alternative pathways to, and limitations on, population expansions.
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- Award ID(s):
- 2203767
- PAR ID:
- 10562589
- Publisher / Repository:
- Society for American Archaeology
- Date Published:
- Format(s):
- Medium: X
- Location:
- New Orleans, LA
- Sponsoring Org:
- National Science Foundation
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