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The obsidian dating method converts the quantity of diffused molecular water within a near‐surface hydration layer to elapsed time using an experimentally derived diffusion coefficient predicted from the structural water content of the glass. Infrared spectroscopic transmission measurements on transparent archaeological samples record vibrational responses of water bands in the near‐infrared region, permitting determination of structural water content (OH), and the amount of diffused ambient water (H2O). In this application, the H2O water band at 5200 cm−1 is measured directly. The accuracy of the approach is assessed by an evaluation of the precision of each contributing variable. The new protocol is evaluated using obsidian artifacts from radiocarbon‐dated deposits at Salamanca Cave in Argentina. [ABSTRACT FROM AUTHOR]

The Lesser Rhea (Rhea pennata), a large flightless bird native to South America, held historical significance as a vital resource for Patagonian hunter–gatherer societies. Despite the species' cultural and ecological importance, the historical population dynamics of R. pennata remain poorly understood. Although present in the archaeological record, its abundance is not consistently documented and the reasons remain unclear. This study investigates the late Holocene population trends of R. pennata using ancient DNA analysis. By analyzing complete mitochondrial genome sequences from dated archaeological specimens, we reveal a significant population increase from 700 to 500 years Before Present (BP), followed by a period of relative stability from 500 to 300 years BP. Subsequently, a subtle decline in population size is observed, coinciding with the arrival of European settlers; however, due to considerable uncertainty in population estimates, definitive conclusions regarding this decline are challenging to make. Historical records indicate heightened rhea hunting during this period, coterminous with a decrease in the abundance of rhea eggshell fragments. It is suggested that climatic factors may have influenced these population dynamics, particularly favoring rhea population growth from 700 to 500 years BP. This study contributes to our understanding of the historical ecology and human‐rhea interactions in Patagonia, emphasizing the importance of interdisciplinary approaches in reconstructing past population dynamics. [ABSTRACT FROM AUTHOR]

We propose an Ideal Specialization Model to help explain the diversity of population growth trajectories exhibited across archaeological regions over thousands of years. The model provides a general set of expectations useful for guiding empirical research, and we provide a concrete example by conducting a preliminary evaluation of three expectations in Central West Argentina. We use kernel density estimates of archaeological radiocarbon, estimates of paleoclimate, and human bone stable isotopes from archaeological remains to evaluate three expectations drawn from the model's dynamics. Based on our results, we suggest that innovations in the production of food and social organization drove demographic transitions and population expansion in the region. The consistency of population expansion in the region positively associates with changes in diet and, potentially, innovations in settlement and social integration. [ABSTRACT FROM AUTHOR]

Salamanca cave (southern Mendoza province) is in the Andean piedmont, a transitional area in which small mammal communities may have been affected by climatic pulses. The site yields three archaeological components covering from the early to the late-Holocene with a mid-Holocene occupational and sedimentological hiatus. Taphonomic analyses of the small mammal assemblages indicate that barn owls (Tyto furcata) were the main accumulation agent, ensuring accurate palaeoecological inferences. Taxonomic composition of the site shows the dominance of Eligmodontia sp. followed by Thylamys pallidior, Phyllotis cf. P. vaccarum-pehuenche and Ctenomys sp., all of them indicative of shrubland and bare ground habitats. Palaeoclimatic inferences indicate a trend to warmer temperatures from the lower to the upper component with a slight increase in humidity in the middle component. This humid pulse is also supported by post-depositional taphonomic processes. The taxonomic structure and abundance of small mammals do not show deep changes amongst the three archaeological components, following the general trend observed in other archaeological sites from the Pampean region, southern Mendoza province and the arid and semi-arid zones of north Patagonia, in which changes in the taxonomic composition of small mammal communities are almost absent since Pleistocene–Holocene transition to late Holocene. [ABSTRACT FROM AUTHOR]

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