Doctoral Dissertation Improvement Award: Variability in Silcrete Heat Treatment Technology and Implications for Modern Human Behavior

This doctoral dissertation research project seeks to better understand the biological, cultural, and environmental contexts out of which modern human behavior emerged. Research has focused heavily on the emergence of complex cognition and the special forms of social learning exhibited by modern humans. Archaeology is well placed to provide insight because it can use the material record to analyze large-scale patterns across deep time to determine when, where, and in what context these traits may have emerged.

An important but relatively understudied proxy for modern human behavior is the use of fire to improve the quality of stone for toolmaking. This technology, known as lithic heat treatment, is thought to be some of the earliest evidence for the ability to recognize and combine abstract concepts through analogical reasoning and may require social learning and teaching.

This research improves understanding of lithic heat treatment technology in the past and how it relates to the evolution of modern human behavior and possibly other transformative technologies such as blacksmithing and ceramics. The project provides training to two undergraduate students in stone tool analysis, database management, and artifact curation.

This project examines how humans heat treated stone raw material in the past through the development of the first large-scale empirical reference dataset of heat treatment technology created through experimental archaeology. These data serve to establish attribute criteria and develop novel methods with empirical support for distinguishing between lithic heat treatment methods in the archaeological record.

The team develops novel methods that are quantitative, probabilistic, inexpensive, and non-destructive to enhance its replicability and generalizability. The archaeological application of these methods focuses on the analysis of three Middle Stone Age archaeological sites near the south coast of South Africa – Pinnacle Point and Boomplaas Cave – to determine how methods of heat treatment varied from ~162,000-years ago to 40,000-years ago.

These sites specifically, are critical to this research because they preserve some of the earliest evidence of lithic heat treatment technology and have long, well-dated sequences that are associated with high-resolution paleoenvironmental and paleoecological records. This allows the researchers to contextualize how Middle Stone Age humans were heat treating stone over ~125,000-years and to determine how this relates to the emergence of modern human behavior.

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.