Flake variation in relation to the application of force

The appearance of new force application techniques in the production of stone artifacts over the course of human evolution has been associated with the increasing technological capacity of hominin groups. Yet, the causal relationship between the knapping practice and the flake characteristics upon which these behavioral inferences rest remains largely untested under controlled settings. Here we present a recent controlled experiment examining the effect of various force application variables (hammer shape; location of force application; angle of blow; hammer displacement speed) on flake morphology. Results indicate that the independent variables interact with flake attributes in a complex way that makes simple analogies between particular attributes and specific force application techniques extremely difficult. However, trade-offs among the variables cast new light on the possible mechanisms underlying variation in force application techniques used in flintknapping. (C) 2014 Elsevier Ltd. All rights reserved.