Hunter-Gatherer persistence and demography in Patagonia (southern South America): the impact of ecological changes during the Pleistocene and Holocene

BERNAL, VALERIA; PEREZ, S. IVAN; POSTILLONE, MARÍA BÁRBARA; RINDEL, D. D.

Hunter-Gatherer Resilience in Bioarchaeological Perspective.

Cambridge University Press

Lugar: Cambridge; Año: 2018; p. 47 - 64

Human populations have been exposed to environmental changes during the Pleistocene-Holocene. Studying whether and in which ways human groups were affected by such changes can contribute to our understanding of the resilience of natural populations to external perturbations. However, the capacity of small populations to respond to a perturbation by resisting damage and/or recovering quickly remains largely unknown. Investigating the causes of persistence and the population dynamics that lead to the recovery of the system is key to understanding resilience in past populations.Patagonia region (southern South America) was peopled around 15,000 years ago by small groups of hunter-gatherers which shared a recent and single origin. These groups have been traditionally seen as homogeneous, being characterized by the consumption of mega-mammals as their main food resource from Late Pleistocene to 400 years BP and the use of lithic technology of projectile points and stone balls. However, significant ecological changes occurred since the early peopling of this region. During the Late Pleistocene the climatic conditions were warm and humid with increased primary productivity. Around 7,500 years BP precipitation levels dropped attaining their present-day values. As a consequence, the frequency of steppe and grass habitats diminished considerably. Such climatic changes along with human activities might have affected the diversity of resources available, which in turn can have effects on the persistence and dynamic of hunter-gatherer populations. Despite the fact that Patagonian groups have been the focus of numerous studies, its responses to ecological changes remain largely unexplored. Here, we will study the persistence and demographic changes of hunter-gatherer populations -as evidences of its resilience- in response to the ecological disturbances in Patagonia region during Late Pleistocene-Holocene. Particularly, we will explore the relationship between the persistence of individual human lineages and population size changes with the variation in faunal composition and trophic interactions that took place during the period under study. With this aim we will analyze molecular data of ancient and modern mtDNA employing Bayesian genealogical reconstruction and Skyline Plot methods to assess lineage diversity and changes in the size of human populations. Palaeontological and zooarchaeological data will be analyzed by means of complex network methods in order to gain insight into the ecological changes that human populations from North Patagonia had to face in the last 10,000 years.