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The purpose of this paper is to begin to understand human mobility through rock transport at different times in two areas with different environmental characteristics: the Southern Deseado Massif and the basaltic canyons north of the Santa Cruz River. We focus on obsidian, which has a clear geochemical signature and an uneven distribution. Additionally, we use macroscopic information on siliceous rocks, which at present have only been identified in northern areas, although they may also be recovered randomly and in low frequencies in southern ones. During the initial peopling of the Southern Deseado Massif (ca. 10,800 BP), inhabitants were transporting black obsidian as well as translucent chalcedony, probably as part of the individual gear. During the Late Holocene, the number of obsidian artifacts decreased in the Southern Deseado Massif, related to a better knowledge of the high-quality local lithic resources and/or to the existence of higher population densities. Obsidian artifacts are more abundant in the northern Santa Cruz River basin than in the southern Deseado Massif, suggesting the existence of a relationship with areas located to the northwest, close to the obsidian source, as other lines of evidence suggest. In addition, the presence in the basaltic canyons of artifacts made from high-quality siliceous rocks, more abundant and predictable in northern areas, could also be the result of human movements following a north-south direction. [ABSTRACT FROM AUTHOR]

This paper summarizes and discusses the main results achieved over three decades of research on paleodemographic aspects of Late Holocene hunter-gatherers in Northwestern Santa Cruz (Argentina). Research has been guided by a model of regional settlement that proposes that, as a result of the progressive aridization process recorded in Patagonia during the Late Holocene, human groups would have reduced their residential mobility and concentrated their settlements in low altitude basins with water availability, such as Lake Cardiel and Lake Salitroso. Paleodemographic questions derived from the model relate to population regional continuity and dynamics and were tested using several lines of research at regional and local scales. The assessment of the chronological information and temporal trends of the archaeological record at the regional level allowed for a coarse grain paleodemographic approach, and acted as a mean to support hypotheses related to changes in mobility and land use strategies. Building on this, several lines of bioarchaeological evidence were used to address paleodemographic aspects of the model, including temporal, distributional, and compositional studies of the mortuary record, isotopic, morphometric and DNA analyses and the sex and age structure of the skeletal samples recovered in Lake Salitroso basin. Results point to a biological and cultural population continuity in the region during the Late Holocene. Also, a reduction in residential mobility would have favored a slight population growth of Lake Salitroso populations during the last millennium. [ABSTRACT FROM AUTHOR]