Environmental Archaeology The Journal of Human Palaeoecology Bioavailable Strontium in the Southern Andes (Argentina and Chile): A Tool for Tracking Human and Animal Movement (original) (raw)
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Objectives: The goal of this article is to assess the scale of human paleomobility and ecological complementarity between the lowlands and highlands in the southern Andes during the last 2,300 years. By providing isotope results for human bone and teeth samples, we assess a hypothesis of " high residential mobility " suggested on the basis of oxygen isotopes from human remains. Methods: We develop an isotopic assessment of human mobility in a mountain landscape combining strontium and oxygen isotopes. We analyze bone and teeth samples as an approach to life-history changes in spatial residence. Human samples from the main geological units and periods within the last two millennia are selected. Results: We present a framework for the analysis of bioavailable strontium based on the combination of the geological data with isotope results for rodent samples. The 87 Sr/ 86 Sr values from human samples indicate residential stability within geological regions along life history. When comparing strontium and oxygen values for the same human samples, we record a divergent pattern: while d 18 O values for samples from distant regions overlap widely, there are important differences in 87 Sr/ 86 Sr values. Conclusions: Despite the large socioeconomic changes recorded, 87 Sr/ 86 Sr values indicate a persisting scenario of low systematic mobility between the different geological regions. Our results suggest that strontium isotope values provide the most germane means to track patterns of human occupation of distinct regions in complex geological landscapes, offering a much higher spatial resolution than oxygen isotopes in the southern Andes.
Geoarchaeology, 2021
Strontium isotopes facilitate the study of human paleogeography and have widened the scope of archaeological enquiries on mobility. We present an approach based on strontium isotopes (87Sr/86Sr) to study the mobility of hunter–gatherer societies from northwestern Patagonia (Neuquén, Argentina). The analysis is developed on the basis of a macro‐regional geological framework that guides the sampling and interpretation of results. We also present results for fauna to begin building a landscape of bioavailable strontium to be utilized in the interpretation of results from human samples. These first results conform to general expectations and show the most radiogenic 87Sr/86Sr values for the oldest geological provinces, while low values are recorded for recent substrates. Additionally, we provide results for human samples from archaeological sites spanning the last 4000 years, a period during which a number of important socio‐demographic changes occurred. The results in human samples indicate overall isotopic fidelity to the values recorded in the local geology, suggesting a relatively restricted spatial scale of mobility during the late Holocene. This discussion is situated in a biogeographic research framework assessing topographic variation and landscape seasonality, and contributes toward understanding the movements of people, flow of material objects, and circulation of information in the Patagonian Andes.
Geoarchaeology, 2021
Strontium isotopes facilitate the study of human paleogeography and have widened the scope of archaeological enquiries on mobility. We present an approach based on strontium isotopes (87Sr/86Sr) to study the mobility of hunter–gatherer societies from northwestern Patagonia (Neuquén, Argentina). The analysis is developed on the basis of a macro‐regional geological framework that guides the sampling and interpretation of results. We also present results for fauna to begin building a landscape of bioavailable strontium to be utilized in the interpretation of results from human samples. These first results conform to general expectations and show the most radiogenic 87Sr/86Sr values for the oldest geological provinces, while low values are recorded for recent substrates. Additionally, we provide results for human samples from archaeological sites spanning the last 4000years, a period during which a number of important socio‐demographic changes occurred. The results in human samples indicate overall isotopic fidelity to the values recorded in the local geology, suggesting a relatively restricted spatial scale of mobility during the late Holocene. This discussion is situated in a biogeographic research framework as- sessing topographic variation and landscape seasonality, and contributes toward understanding the movements of people, flow of material objects, and circulation of information in the Patagonian Andes.
The Andes are a unique geological and biogeographic feature of South America. From the perspective of human geography, this mountain range provides ready access to highly diverse altitudinally arranged ecosystems. The combination of a geologically and ecologically diverse landscape provides an exceptional context to explore the potential of strontium isotopes to track the movements of people and the conveyance of material culture. Here we develop an isotopic landscape of bioavailable strontium (87Sr/86Sr) that is applied to reconstruct human paleogeography across time in the southern Andes of Argentina and Chile (31°–34°S). These results come from a macro-regional sampling of rodents (N = 65) and plants (N = 26) from modern and archeological contexts. This “Southern Andean Strontium Transect” extends over 350 km across the Andes, encompassing the main geological provinces between the Pacific coast (Chile) and the eastern lowlands (Argentina). We follow a recently developed approach to isoscape construction based on Random Forest regression and GIS analysis. Our results suggest that bioavailable strontium is tightly linked with bedrock geology and offers a highly resolved proxy to track human paleogeography involving the levels of territories or daily mobility and anomalous events that disrupt home ranges, such as migration. The southern Andes provide an ideal geological setting to develop this approach, since the geological variation in rock age and composition produces distinctive isotopic signatures for each main biogeographical region. Finally, we apply this framework to a set of results from human remains from the Uspallata Valley in Mendoza (Argentina), to assess the incidence of migration in the key period of the consolidation of agropastoral economies between AD 800 and 1400. The application of the isoscape to the values from human remains confirms the persistence of human groups with relatively restricted territories encompassing Uspallata and the adjacent Precordillera between AD 800 and 1500. We also identify a pulse of human migration between AD 1280 and 1420, shortly preceding the Inka conquest. Looking forward, we expect to converge with ongoing efforts in South America to build a continental research framework to track the movement of people, animals, and artifacts across space and time
Scientific Reports, 2020
We present isotopic and morphometric evidence suggesting the migration of farmers in the southern Andes in the period AD 1270-1420, leading up to the Inka conquest occurring ~ AD 1400. This is based on the interdisciplinary study of human remains from archaeological cemeteries in the Andean Uspallata Valley (Argentina), located in the southern frontier of the Inka Empire. The studied samples span AD 800-1500, encompassing the highly dynamic Late Intermediate Period and culminating with the imperial expansion. Our research combines a macro-regional study of human paleomobility and migration based on a new strontium isoscape across the Andes that allows identifying locals and migrants, a geometric morphometric analysis of cranio-facial morphology suggesting separate ancestral lineages, and a paleodietary reconstruction based on stable isotopes showing that the migrants had diets exceptionally high in C 4 plants and largely based on maize agriculture. Significantly, this migration influx occurred during a period of regional demographic increase and would have been part of a widespread period of change in settlement patterns and population movements that preceded the Inka expansion. These processes increased local social diversity and may have been subsequently utilized by the Inka to channel interaction with the local societies. Migrations are an intrinsic aspect of human societies in the present as in the past 1-3. While their dynamics differ 4,5 , migrations occurred across levels of socioeconomic complexity, from small-scale mobile societies to OPEN
PLOS ONE, 2021
Strontium isotope (87Sr/86Sr) analysis of human skeletal remains is an important method in archaeology to examine past human mobility and landscape use. 87Sr/86Sr signatures of a given location are largely determined by the underlying bedrock, and these geology specific isotope signatures are incorporated into skeletal tissue through food and water, often permitting the differentiation of local and non-local individuals in past human populations. This study presents the results of a systematic survey of modern flora and fauna (n = 100) from 14 locations to map the bioavailable 87Sr/86Sr signatures of the Conchucos region, an area where the extent of geologic variability was previously unknown. We illustrate the necessity to examine the variation in 87Sr/86Sr values of the different geological formations available to human land use to document the range of possible local 87Sr/86Sr values. Within the Conchucos region we found significant variation in environmental 87Sr/86Sr values (0....