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This paper explores how significant are the ecological and climatic variables to influence the stable isotopes of guanacos. Lama guanicoe bone collagen carbon and nitrogen stable isotope ratios are assumed as a macro regional average value in west Argentina, mostly as a baseline to model archaeological human diet. If stable isotopes on mammals reflex ecology and climate, we need to know how those variables influence mammals bone stable isotope ratio. This paper analyses the 13C/12C and 15 N/14N ratio on bone collagen on 122 guanacos from Northwest Patagonia during the Holocene. The results confirm significant variation in both isotopes between Monte and Andean-Patagonian specimens. Guanacos from Monte shows higher δ13C and δ15N than those from Andean-Patagonian. Temporal trends indicate variation through Holocene but this variation is not spatially homogeneous. In this paper we suggest that Medieval Climatic Anomaly had stronger effect in Monte desert than in Patagonia desert, generating driest and/or hottest conditions between 1250 and 600 years BP. Those variations need to be considered to reconstruct human diet at least during the second part of the Holocene. [ABSTRACT FROM AUTHOR]

In this paper, the analysis of a radiocarbon database of the North Coast of Santa Cruz (central Patagonia, Argentina), is presented. Dated archaeological samples were obtained from 56 different types of archaeological sites (open-air -residential sites and burials-, and also rock shelters). The objective of this paper is assessing the continuities and discontinuities in the chronological signal of the area and identifying tendencies along the Holocene. The database currently contains 75 radiocarbon dates falling between ca. 8000 and 300 BP. The radiocarbon data base provides information on the chronological, spatial and contextual variability of the archaeological record of North Coast of Santa Cruz. By means of different analysis of sum of probabilities, we present three different chronological moments of human use of the coast and intermediate zone can be identified. A first moment is represented by early evidence of settlement during Middle Holocene. A second moment corresponds to a hiatus between ca. 5800 and ca. 3900 BP without archaeological evidence. Finally, a third moment is where an increasing of chronological signal occurred, related to greater artifactual variability and an increase in the intensity of human settlement in the Patagonian region. The causes that could have influenced in the discontinuity of the chronological signal of the study area, and the characteristics of the different moments identified are discussed. [ABSTRACT FROM AUTHOR]

Archaeology has been using stable oxygen as an isotopic tracer linked with water consumption for decades, and it has been demonstrated to be a powerful tool to assess paleomobility in bioarchaeology. Central-eastern North Patagonia (Argentina) is an especially appropriate region to apply it since it presents a high density of hunter-gatherer burials, it was a nodal zone criss-crossed by an extensive network of important routes, and it is characterized by a high environmental fragmentation due to the scarcity of fresh water sources. The aim of this paper is to build an empirical stable oxygen isotope baseline of terrestrial surface waters to assess the potentiality of tracing past human movement. We analyzed 46 water samples from 13 locations with permanent sources (rivers, springs, streams), compared it with predictions of precipitation and evaluated it considering seasonal variation, altitude and distance from the coast. Our results show that different post-precipitation processes change the isotopic signal from the sources with respect to the local precipitation, and highlight the relevance of analyzing terrestrial water sources. According to their oxygen isotope values we defined five hydrologic zones: Colorado River, Negro River, Closed Basins and Plains, Eastern and Western Somuncurá Foothills. Their identification shows the potential to address past human movement using stable oxygen water baselines in central-eastern North Patagonia. [ABSTRACT FROM AUTHOR]

Abstract Over the last decade, we have conducted an actualistic taphonomic research program in the Humid Pampas of Argentina, in order to build a corpus of information about the taphonomic agents and processes characterizing this sub-region. In this paper, we present a summary of our results after ten years of actualistic taphonomic studies in the Pampas. Our program includes both naturalistic and experimental research. Some of the controlled experiments consist of studies with different-aged guanaco bones, including sub-aerial weathering in a controlled environment, and water transport with disarticulated bones. Other studies were conducted at a local zoo, where we offered different types of prey to native small-sized carnivores (canids, felids, mustelids, and mephitids). Our naturalistic observations include the development of taphonomic transects in different environments. Through this method, we were able to study different topics among which some of the more significant are the movement of bones by small-sized carnivores and the distribution of beached Magellanic penguin specimens along the coast. Particular studies included the analyses of the content of dens occupied by small carnivores, the effects of a grassland fire in a vertebrate assemblage, the modifications produced by a local rodent -vizcacha- in the landscape, and the damage generated by pumas in guanaco carcasses. After ten years of systematic research we contributed to identify the potential mixture between modern bones and the archaeological record in relation to the environment; to determine bone preservation biases according to the properties of the record; to recognize agents responsible of bone accumulation and alteration; and to establish diagnostic criteria in order to differentiate cultural from natural patterns. [ABSTRACT FROM AUTHOR]

This paper shows the preliminary results of the zooarchaeological analysis of Dupuy Rockshelter (La Toma, San Luis Province, Argentina). This rock shelter has evidence of Late Holocene (Last Millennium) human occupation dating from 340 ± 40 BP. Some species, including Lama guanicoe and Ozotoceros bezoarticus , were exploited and their bones were used as raw material to make instruments. The zooarchaeological analysis is complemented by geological and phytoarchaological evidence which indicates a humid environment during the Holocene and a mixed diet that included vegetables. [ABSTRACT FROM AUTHOR]

Archaeological radiocarbon databases are being increasingly used as a proxy of past demographic trends. In this paper we compile and analyze an extensive database of paleoecological information and 14 C dates from archaeological sites in northwestern Patagonia (Argentina, South America). On this basis, we assess the regional distribution of human populations since the late Pleistocene, and their relation with the evolution of Patagonian climate and landscapes. We explore the spatial and temporal distribution of evidence and discuss sampling biases affecting the record in different ecological contexts. The analysis is set in the frame of three main ecological regions that have implications for human subsistence: Andean forest, grass steppe, and shrub steppe. The intensity of the archaeological signal differs among these regions through time, being stronger and more homogeneous in the grass steppe. In the Andean forest and the shrub steppe the signal is weaker and even absent during short periods of the middle Holocene. We suggest likely sampling biases contributing to these tendencies, since these three regions present variable research cover and intensity. On the other hand, we also suggest that these differences may reflect variations in the intensity of human occupation, in favor of more attractive environments for hunting (i.e., areas where guanaco are generally more abundant). This macro-regional synthesis of the paleoecology and archaeology of northwestern Patagonia provides a platform for developing future oriented research. [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]

This paper compiles a database of radiocarbon dates of archaeological sites that are currently available for the Pampean region. Based on the probability distribution of radiocarbon dates from this database, major temporal trends are defined, taphonomic and scientific biases are evaluated, and their implications for demography are suggested. Results indicate a continuous archaeological signal between ca. 14,500 and 100 cal BP. During the final Late Pleistocene and the Early Holocene, the archaeological signal is low in ca. 14,500–12,800 cal BP, and increases to a moderate and continuous signal in ca. 12,800–7500 cal BP. The archaeological signal for the former lapse correspond to the early peopling of the region and is related to the inhabiting and exploitation of key landforms (e.g., rock shelters, river valleys) and critical resources (e.g., lithic raw material, water). The low amount of available dates for the Middle Holocene (ca. 7400–3700 cal BP), and the associated archaeological signal would be due to the combination of various factors such as taphonomic biases, organization of prehistoric populations, and even a possible low population density. The obtained low but continuous signal for this period are discussed in the framework of the proposed models for the human occupation of the region suggesting that a hypothesis about population extinctions and disruptions processes could not be sustained. Finally, during the Late Holocene (from 3700 to 100 cal BP) human occupations are recorded in all the micro-regions. Regardless of biases, this signal is interpreted as an increase in demographic density at a regional level. [ABSTRACT FROM AUTHOR]

Abstract: Paso Otero archaeological locality (Pampean region, Argentina) has provided detailed paleoenvironmental reconstructions and faunal assemblages from the Pleistocene/Holocene transition and Early Holocene. This time span is represented by Paso Otero 5 (c. 10 450–10 200 14C BP; 12 593–11 353 cal. BP) and Paso Otero 4 (c. 9900–7700 14C BP; 10 667–7982 cal. BP). Palaeoenvironmental studies have been carried out on the basis of data derived from geoarchaeological, sedimentary, palynofacies, pollen, diatoms and silica microremains. Unlike other areas of the Pampean region, bone assemblages from Paso Otero include high representation and diversity of taxa. In this paper, paleoenvironmental reconstructions and faunal assemblages from both sites are integrated in order to discuss the consistency of the inferences derived from the two lines of evidence, its contribution to the paleoecological scenarios, and to faunal extinctions. It is suggested that not only hunting pressure but the mere presence of humans was a factor in ecosystem disturbance and is the most parsimonious explanation for the process of extinction. [Copyright &y& Elsevier]

Abstract: This paper analyzes the spatial organization of two layers corresponding to the first half of the Middle Holocene from the Hornillos 2 rockshelter (Susques, Jujuy Province). Some important issues taken into account are the good preservation of the site and the sedimentary deposition processes which coincide with paleoclimate aspects. Correlation of different archaeological lines of evidence allows interpretation of the connection between several activity areas and their occupational intensity. There is a trash heap related to a short occupation period at the beginning of the Middle Holocene and a main zone of intense activity ca. 6200 yrs BP. These facts are in accordance with the archaeological expectations proposed for certain periods of the Middle Holocene. [Copyright &y& Elsevier]