Peopling time, spatial occupation and demography of Late Pleistocene-Holocene human population from Patagonia

The settlement of Patagonia has been the subject of extensive research, although key questions about the timing of arrival of the first humans and the subsequent patterns of dispersal and demographic changes within the region remain largely unresolved. In this study we evaluated the most probable date for the initial peopling of Patagonia and explored the temporal and spatial changes in population size along Late Pleistocene-Holocene by using robust statistical methods for the analysis of radiocarbon dates and molecular data. We suggest that the first humans probably arrived to Patagonia around 17,000-14,000 years BP, a few thousands of years earlier than generally stated. Within the region, the populations experienced a sustained and slow growth until the transition Pleistocene-Holocene, when the population size started to increase, with a remarkable acceleration after 7000-5000 years BP and reaching its maximum at 1000 years BP. The spatial occupation was not homogeneous across the region though, changing from a more intense continental occupation to a coastal occupation in the Late Holocene. This pattern of peopling and population expansion, obtained here on the basis of a rigorous and comprehensive quantitative approach, will allow the future evaluation of formal models about the ecological and cultural processes that drove the evolution of the human populations from Patagonia.