Confronting complexities of artifact–geofact debates: re-analysis of a coarse volcanic rock assemblage from Chilean Patagonia

Abstract

An assemblage of coarse volcanic rock (CVR) derived from the walls of a rockshelter in Aisén, Chile was recently described as consisting of bifaces, projectile points, and picks [Prentiss et al. 2015a. Lithic Technology 40:112–127]. The objects are not universally accepted as cultural, however, on account of both their crude appearance and the fact that CVR industries have not been previously identified in either the valley where the objects were found or elsewhere in Patagonia. We present the results of three independent studies—a single-blind poll of lithics specialists, on-site assessment of stone availability and natural agents of modification, and protein residue analysis using cross-over immunoelectrophoresis—none of which support a cultural origin for the CVR specimens. We discuss these findings in terms of a more general debate in lithics analysis regarding reconciliation of conflicting evidence and interpretations in ambiguous cases.

Keywords:

• Coarse volcanic rock
• Cultural vs. natural stone objects
• Inter-observer variation
• Patagonia
• Protein residue analysis

Acknowledgements

The authors thank Dr Anna Marie Prentiss for providing information related to the 2012 excavations, and for engaging and good-natured discussions regarding the CVR assemblage; the Consejo de Monumentos Nacionales de Chile for granting the 2015–2016 research permit (Ingreso CMN #6088); Lino Mauriera for allowing us access to his estate and for his gracious hospitality; Eduardo Silva, Simón Sierralta, Renata Gutiérrez, and Maria Luisa Gómez for their hard work during the 2015 field season; participants in the IX Jornadas de Arqueología de la Patagonia workshop; the University of Michigan for funding RG's participation in the IX Jornadas de Arqueología de la Patagonia and 2015 excavations; PaleoResearch Institute for the protein residue analysis; and Grant McCall and two anonymous reviewers whose comments helped to improve the paper. The 2012 research at RI-6 was funded by a grant from FONDECYT (#1110556).

Notes on Contributors

Raven Garvey is an Assistant Professor of Anthropology at the University of Michigan and an Assistant Curator at the University of Michigan Museum of Anthropological Archaeology. Her research in Patagonia explores interactions between prehistoric hunter-gatherers and their environments to better understand the relative importance of ecological and cultural factors in shaping behavioral and technological adaptations to changing conditions.

Francisco Mena is a Ph.D. from UCLA and former deputy director at the Museo Chileno de Arte Precolombino and professor at the Universidad de Chile, Santiago. From here and from his current position as a Resident Researcher at the Centro de Investigación en Ecosistemas de la Patagonia (CIEP) at Coyhaique, he has led research in several Andean valleys at the Chilean Patagonia and particularly on the Ibáñez valley, where the RI 6W site is located.

Notes

1 The acronym for cross-over immunoelectrophoresis, CIEP, happens to coincide with that of FM's employer, the Centro de Investigaciones en Ecosistemas de la Patagonia. Here, CIEP is used exclusively to refer to cross-over immunoelectrophoresis.