Past human decision-making based on stone tool performance: Experiments to test the influence of raw material variability and edge angle design on tool function

Abstract

One of the main interests in the interpretation of the archaeological record and its variability within and through time and space is the production and use of past human stone tool technologies. Tool design and function are inevitably intertwined and strongly related to tool use. Understanding tool design provides information about early human technological adaptations and reflects human behaviour in the sense of conscious or unconscious decision-making. Nevertheless, the reason for major changes (including novelties, innovations, and loss) in past human stone tool technology is still poorly understood. A comprehensive approach focusing on tool function (What was the tool meant for?) and use (What was the tool used for?) can help to overcome this gap. While tool function (including performance) can be investigated experimentally, tool use can be addressed with use-wear analyses. These questions can be best investigated on technological systems showing little tool variability but strong evidence of maintenance and long-term use, such as Middle Palaeolithic industries. The Late Middle Palaeolithic record of Central and Eastern Europe is marked by the emergence of an asymmetric tool-type called Keilmesser (bifacial backed knives). Due to their sophisticated morphology, Keilmesser as a case study offer the potential to address aspects of raw material selection, tool production, maintenance, and reworking. This paper presents the results of an experiment designed to study the tool performance of Keilmesser from three archaeological sites, namely Balver H¨ ohle, the Upper site of Buhlen and Grotte de Ramioul by testing raw material, edge angle and movement as independent variables. A highly controlled, sequential experiment was conducted using a mechanical device performing unidirectional cutting and carving movements on hard contact material. Results demonstrate the possibility to perform the mentioned task with 35◦ and 45◦ edge angles, maintaining function, albeit at differing levels of efficiency. The data has a direct impact on the interpretation of the archaeological assemblages regarding aspects such as stone tool morphology and resharpening. At the same time, the study highlights the importance of raw material analysis to understand the variability in the archaeological record and the implications on past human decision-making strategies.