Biomechanical strategies for accuracy and force generation during stone tool production

摘要: Abstract Multiple hominin species used and produced stone tools, the archaeological record provides evidence that tool behaviors intensified among later members of genus Homo . This intensification is widely thought to be product cognitive anatomical adaptations enabled taxa produce tools more efficiently relative earlier species. study builds upon recent investigations knapping motions modern humans test whether aspects our upper limb anatomy contribute accuracy and/or efficiency. Knapping kinematics were captured from eight experienced knappers using a Vicon motion capture system. Each subject series Oldowan bifacial choppers under two conditions: with normal wrist mobility while wearing brace reduced extension (∼30°–35°), simulating one aspect likely primitive condition. Under conditions, subjects employed variant proximal-to-distal joint sequence common throwing activities: initiated down-swing at shoulder proceeded distally, increasing peak linear angular velocities elbow wrist. At wrist, utilized ‘dart-thrower's arc,’ most stable plane radiocarpal motion, during which coupled radial deviation flexion ulnar deviation. With an unrestrained achieved significantly greater target accuracy, velocities, hand compared braced Additionally, wrist's ability reach high degrees (≥28.5°) following strike may decrease risk carpal ligamentous damage caused by hyperextension. These results suggest in contributes tool-making performance.