EMG STUDY OF HAND MUSCLE RECRUITMENT DURING HARD HAMMER PERCUSSION MANUFACTURE OF OLDOWAN TOOLS

The activity of 17 hand muscles was monitored by electromyography (EMG ) in three subjects during hard hammer percussion manufacture of Oldow an tools. Two of the subjects were archaeologists experienced in the r eplication of prehistoric stone tools. Simultaneous videotapes recorde d grips associated with the muscle activities. The purpose of the stud y was to identify the muscles most likely to have been strongly and re peatedly recruited by early hominids during stone tool-making. This in formation is fundamental to the identification of skeletal features th at may reliably predict tool-making capabilities in early hominids. Th e muscles most frequently recruited at high force levels for strong pr ecision pinch grips required to control the hammerstone and core are t he intrinsic muscles of the fifth finger and the thumb/index finger re gions. A productive search for skeletal evidence of habitual Oldowan t ool-making behavior will therefore be in the regions of the hand stres sed by these intrinsic muscles and in the joint configurations affecti ng the relative lengths of their moment arms. (C) 1998 Wiley-Liss, Inc .