‘To and fro’ the southern Andean highlands (Argentina and Chile): Archaeometric insights on geographic vectors of mobility

Abstract

The Andes mountain range is one key physiographic feature of South America with the potential to have acted as a barrier and corridor for human societies. The goal of this paper is to assess from where and how were the highlands utilized during the last 2000 years, which is a key period witnessing the development of productive economies and changes in the organization of mobility. We develop a regional case study focused on the highland wetland Laguna del Diamante (3300 masl), which is a highly productive ecosystem only accessible during summer. This case is based on a multidisciplinary approach combining: a) geochemical characterization of obsidian sources located in the highlands and artifacts; b) isotopic approach to ranges of paleomobility of individuals by means of 87Sr/86Sr; and c) stylistic study of ceramic assemblages. The two main obsidian types from the highlands have restricted and decaying spatial distribution, suggesting that these archaeological distributions track part of human circuits of mobility instead of indirect transport acquisition. Their archaeological distribution is heavily skewed towards the western Andean slope. We present strontium isotope values for four teeth and bone samples from two individuals recovered in the area, which are interpreted in reference to a preliminary baseline of biologically available strontium. We infer that these individuals had ranges of paleomobility systematically connecting the western slope with the highlands. The analysis of the ceramic assemblages shows that most of the diagnostic sherds can be assigned to styles that have distributional cores in the Central Valley of Chile up until the time of Inca presence, while only a minimum portion of the sample can be assigned to distributional cores on the eastern slope. By integrating the patterns in the transport of obsidian and ceramic artifacts and the paleomobility of individuals, we find support for the existence of dominant access to the highlands from the western Andean slope. A GIS-based analysis of the seasonality of precipitation shows that the western slope presents more pronounced and drier summer months, providing a context that contributes to explain these patterns. These results contradict previous interpretations suggesting that the archaeological record from the highlands is more directly tied to human groups inhabiting the eastern lowlands during most of the year. Beyond the geographic debate, this issue has an impact on the subsistence organization of the incoming groups, on the socio-economic role of the highlands, and on the demographic contexts leading to trajectories of economic intensification in both Andean slopes. This research contributes to build a framework for comparative research on human use of highland environments.