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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]

• Six obsidian sources increased their use in the Late Holocene in north Patagonia. • The closer source to Diamante Valley, is the least used. • The best quality source, Las Cargas, was the most used across the Late Holocene. • Obsidian helped to minimize risk in the occupation of high elevation locations. • Obsidian exchange routes may find a pattern in least cost path analysis results. • Exchange of obsidian followed routes through High elevations villages to sources. In this paper we explore obsidian conveyance in the Diamante Valley, in northwestern Patagonia, Argentina. Obsidian is the third most-common toolstone used in the Diamante Valley after basalts and local cryptocrystallines. Obsidian artifacts are predominantly projectile points and bifaces, with few cores and early-stage reduction debris. To explain these patterns, we conducted XRF sourcing and technological analysis of 177 obsidian artifacts collected there. We also conducted a GIS-based least cost path analysis to assess the costs of conveying obsidian from sources to sites in the Diamante watershed. We found that hunter-gatherers used Las Cargas as the principal obsidian source, followed by Maule 1 and 2, El Peceño, and Coche Quemado. The nearest source, Laguna del Diamante, was the least used. These data, combined with an analysis of the ways cores, formed tools, and debitage types were conveyed and ultimately deposited at sites in the Diamante watershed, suggest a late Holocene pattern of highland-oriented indirect access, implying highland village sites likely served as nodes in a regional and extraregional exchange network focused not only on obsidian but also on other goods, information, and social obligations. [ABSTRACT FROM AUTHOR]

A biogeographic model used to describe human peopling of southern Mendoza, central western Argentina, proposed an intensification process activated by an increase in population growth rate during the Late Holocene. During this process, high‐ranked resources at the surroundings of residential camps were depleted, and hunter–gatherers broadened their diet by incorporating a larger number of low‐ranked prey and domesticated plant resources. In this paper, we evaluate an alternative hypothesis, focusing on zooarchaeological data from the Diamante River basin. The results show that faunal resource intensification does not appear to have occurred in the Diamante River basin during the Late Holocene. Faunal consumption in Diamante River basin mainly reflects the local fauna in each ecological zone. The data do not show a lack of higher ranked resources. We suggest it is more likely that the demographic increase was not significant enough to cause an impact on the faunal resources. The archaeological evidence should be improved and analysed in smaller scales to continue with the intensification debate. [ABSTRACT FROM AUTHOR]

El registro arqueológico de cazadores-recolectores localizado en ambientes de altura ha sido ampliamente debatido en la literatura mundial. Las discusiones se han centrado en su funcionalidad, cronología, complementariedad con ambientes bajos y significado en los procesos de poblamiento de distintas regiones. Los Andes meridionales cuentan con un amplio espacio cordillerano dentro del cual se emplazan una serie de sitios arqueológicos localizados a aproximadamente 3.000 m snm. Las duras condiciones climáticas de estos ambientes, así como la presencia de estructuras habitacionales, despertó el interés de los investigadores en relación con su funcionalidad, tiempo de permanencia y manejo de los recursos locales. En este trabajo se presenta la información zooarqueológica de cuatro sitios de altura localizados en un sector de los Andes meridionales, en el sur de la provincia de Mendoza, Argentina: El Indígeno, Los Peuquenes, Laguna del Diamante S-4 y Risco de los Indios. El material arqueofaunístico analizado es evaluado a la luz de las características ambientales, los costos de transporte y la funcionalidad de estas locaciones en relación con los circuitos de explotación anual. Los resultados muestran un uso de taxones restringido, con un fuerte énfasis en el guanaco, y un escaso transporte de fauna desde y hacia pisos ecológicos localizados a menor altitud. Todo esto sugiere el uso de los sitios de manera residencial y no como lugares de obtención de presas para su procesamiento y traslado hacia localizaciones más bajas. [ABSTRACT FROM AUTHOR]

• The population trend of late Pleistocene-Holocene hunter-gatherers changed its trajectory ca. 2,300 cal years BP coincident with the adoption of domesticates. • After 2,300 cal years BP, a significant increase in human population occurred. We observe population increases ("booms") followed by notable drops ("busts"). • Stable isotope (ẟ13C) on human bone follow a similar trend, indicating an increased consumption of maize during the "boom" periods and a decreased consumption during the "bust" periods. • We propose that human population changes during the last 2,300 cal years BP correlate with levels of maize consumption. This paper explores the relationships between population change and human diet after the adoption of domesticated resources in northwest Mendoza, a subregion of central western Argentina (CWA). To estimate population, we used summed probability distributions of radiocarbon ages (RC-SPD). We used carbon and nitrogen stable isotope values (ẟ13C co , ẟ13C ca , and ẟ15N) obtained on human bone (collagen and carbonate) to reconstruct human diet. The population trend of late Pleistocene-Holocene hunter-gatherers changed its trajectory ca. 2300 cal years BP coincident with the adoption of domesticates. After this date, a significant increase in human population occurred. We observe population increases ("booms") followed by notable drops ("busts"). Stable isotopes (ẟ13C) on human bone follow a similar trend, indicating an increased consumption of maize during the "boom" periods and a decreased consumption during the "bust" periods. Based on the association between estimated changes in human population and changes in human bone isotope values over the last 2300 cal years BP, we propose that levels of maize consumption emerge from human predator–prey and plant-herbivore interactions. The use of maize, thus, is not part of a social evolutionary stage, but, rather, an outcome of continuous social-ecological process in which maize use may increase or decrease over time. [ABSTRACT FROM AUTHOR]