On the evolution of limestone-tempered pottery in the American Midwest: an experimental assessment of vessel weight and its relationship to other functional/mechanical properties

Abstract

During the Middle and Late Woodland periods in the American Midwest some small-scale societies transitioned from grit to limestone as the primary clay temper. Limestone offers experimentally demonstrated benefits to vessel manufacture, including decreased wall thickness, but given the society-wide changes in mobility and exchange that also occurred, we investigated whether the use of limestone temper resulted in a different vessel weight relative to an analogous grit-tempered vessel. Our analyses demonstrated a significant difference: post-firing, limestone-tempered vessels were 4.5% lighter than grit-tempered ones. The combination of reduced weight and other benefits could help explain why limestone became the predominant temper type throughout much of the Midwest. These issues have direct analogs in the biological realm, and we use three concepts from evolutionary biology–modularity, mosaic evolution, and constraint–to investigate the role limestone temper played not only in vessel weight but also in other aspects of vessel production and use.