Biface Reduction and the Measurement of Dalton Curation: A Southeastern United States Case Study

Stone tools were reduced during use, with implications both for classification and curation rates. Ballenger's “expended utility” (EU) is a continuous reduction measure devised for Dalton bifaces, described by its mean but also its distribution among specimens. We validate EU as a reduction measure by reference to experimental and contextual controls. We compare EU between the “special context” Dalton assemblages Sloan and Hawkins in Arkansas and Ballenger's eastern Oklahoma “occupation context” ones. Then we fit EU distributions to mathematical functions to model the curation process. Results show that Oklahoma bifaces were better curated than Arkansas ones. Fitting distributions to the Gompertz-Makeham model efficiently describes distributions' shape and scale, which are as important to know as central tendency. Curation is not a categorical state but a continuous variable whose complex variation implicates complex causes.