This project examines the relationships between the shapes and orientations of hand joints and the levels and directions of forces normally transmitted through the hands of archaic and recent humans. The skeletal samples to be studied consist of Neandertals, Near Eastern early modern humans, Upper Paleolithic humans (90,000 to 20,000 years B.P.) and recent Holocene humans. Both Neandertals and early modern humans used similar Middle Paleolithic stone tools, whereas later Upper Paleolithic humans are associated with stone tool industries having higher frequencies of smaller, standardized tool types which required an increased range of both power and precision grips to manufacture and employ. The three-dimensional shape and orientation of the wrist and finger articulations are measured using stereo-photogrammetry. Correlation analysis is used to determine the relative contribution of habitual force levels and hand muscle mechanical advantages, to between-sample differences in joint shapes. The existence of between-sample differences in hand joint anatomy indicative of altered frequencies of manipulative behaviors that cannot be explained by force transmission levels would confirm that significant behavioral differences in tool manipulation existed between Late Pleistocene human groups. Ultimately, between-group differences in tool usage could have contributed to the eventual adaptive success of early anatomically modern humans.
