Abstract
Newly described Oldowan stone tools from Swartkrans Member 1 Lower Bank have highlighted important differences in raw material use and knapping methods when compared to Sterkfontein Member 5 East. This variability has been correlated to contrasting habitats surrounding these caves and the presence of carnivores, suggesting that ecological factors may have influenced tool manufacturing in the Early Pleistocene. However, the strength of behavioral ecological interpretations rests upon the identification of adaptive advantages in employing specific reduction strategies. Knapping experiments are used to compare the flaking efficiency of bipolar and freehand reduction, which measures the rate at which these methods convert core mass into cutting edge length. Results suggest that bipolar knapping is an efficient means of producing useable flakes, and its use at Swartkrans potentially reflects adaptations to limiting predation risks.