Collaborative Research: Functional Analysis of Lithic Artifacts

Humans have the capacity to modify their environments through a large set of inter-generationally transmitted engineering skills. The archaeological record addresses questions about the origins of these skills and can test hypotheses about why, when, and where they evolved. Building from this broader context, this project examines whether prehistoric people discovered, and then transmitted, a way to increase adhesion between individual components of their toolkits called “backing” (blunting).

This research impacts human technological evolution by exploring if backing influenced stone tool function. This project takes a substantial inter-disciplinary step forward via the integration of archaeology, materials sciences, 3D morphometrics, and adhesive engineering in both controlled and actualistic experiments. The experimental collections generated from tests will be available for general study.

The data will be permanently stored and freely accessible for download in the Open Science Framework (OSF) and through public education and outreach activities. Since backed stone tools are frequent implements found at sites relevant to the broader late Pleistocene human global dispersals, this project will advance understanding of the behavioral and technological adaptations that determined how our species came to colonize the planet.

The stone tool manufacturing technique of “backing” refers to the blunting of a flake’s edge(s) at, or near to, a 90° angle. Backed tools have a long prehistory, extending over 250,000-years. But why blunt a sharp edge that toolmakers can otherwise use for a variety of practical tasks, such as butchery, engraving, or processing plant material?

One functional hypothesis is that backing enabled early humans to attach stone tools more effectively to wooden handles. If the functional hypothesis is true, then backing represents a significant Stone Age innovation in adhesion engineering. This project involves a systematic program of robust, controlled experimental tests investigating the apparent adhesion advantages of backed versus un-backed tools used as projectile weapon inserts.

This project constructs backed and un-backed tools using four common rock types: chert, quartz, quartzite, and heat-treated silcrete. These tools are then used in four controlled tests to understand whether backed tools offer significant adhesion advantages over un-backed flakes. Regardless of a positive or negative result, this project has implications for understanding human behavioral evolution, technology, and tool use.

This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.