Lithic miniaturization as adaptive strategy: a case study from Boomplaas Cave, South Africa

Lithic miniaturization is a multivariate and evolutionarily significant technological phenomenon involving backed tools, bladelets, small retouched tools, flakes, and small cores. This paper investigates the proximate causes for variability in lithic miniaturization processes during Marine Isotope Stage 2 (c. 29-12 ka) in southern Africa. We test the hypothesis that lithic miniaturization represents a form of adaptive behavior by examining its relationship to site occupation intensity and rainfall seasonality at Boomplaas Cave in South Africa. These are two widely cited explanations for shifts in the organization of hunter-gatherer technologies and the data required for testing them are also readily available. We combine several lithic variables, macrofauna and microfauna indicators, and other archeological data to test the hypotheses. We find evidence that demographic processes impacted choices of technology within contexts of shifting rainfall seasonality, aridity, and rapidly rising Late Glacial sea-levels. In this context, Late Glacial humans converged on a small number of high payoff strategies including technological efficiency through bipolar bladelet production, greater production of ostrich eggshell ornaments and water containers, and a reorganized subsistence strategy targeting lower yield small mammals. The results demonstrate that lithic miniaturization was a strategic choice rather than an inevitable technological outcome. The outcomes have implications for understanding global instances of lithic miniaturization and their relationship to rapidly shifting paleoenvironments.