Applying Brantingham's neutral model of stone raw material procurement to the Pinnacle Point Middle Stone Age record, Western Cape, South Africa

Abstract

The Palaeo-Agulhas Plain (PAP), when exposed, presented Middle Stone Age (MSA) foragers at Pinnacle Point (PP) on the South Coast of South Africa with new sources of raw materials to make stone tools. Sea-level fluctuations and the changing size of the Paleo-Agulhas Plain throughout the Pleistocene PP record ∼165 ka to 50 ka would have altered the availability of different resources, thus potentially forcing new raw material procurement strategies. The relative frequencies of raw material throughout the PP sequence shows that frequencies of raw material types did change, especially after 90 ka. What caused these changing frequencies is debated and centers on whether targeted procurement of specific raw materials was the cause, or if simple raw material availability and abundance due to the changing environmental context in conjunction with opportunistic procurement drove such shifts. The application of a neutral model of stone raw material procurement presented here evaluates whether random walk in the region surrounding the PP site during different coastline configurations (Marine Isotope Stage 6, 5, and 4) explains the observed shifts in raw material usage. Put differently, did opportunistic acquisition of raw materials during random walk in these different environments cause the observed raw material pattern? Model simulations and a sensitivity analysis provide no convincing evidence that observed raw material frequencies at PP resulted from opportunistic acquisition during random walk.