Cutmarks and hominid handedness

Abstract

Handedness in humans has been linked to brain lateralization and the evolution of language, but recent data on chimpanzee tool use suggest that the lateralization of hand and brain function may have instead preceded the time when the hominid and panid lineages split. The hominid paleontological and archaeological records are two sources for testing this hypothesis by helping to establish the antiquity of hominid handedness. As such, several methods have been proposed for identifying traces of hominid handedness in those records. Included among those methods is using the orientation of stone tool cutmarks on ungulate limb bone fragments. Here we report on an experiment created to test the accuracy and efficacy of one such method proposed by Bromage and his colleagues [Bromage, T.G., Boyde, A., 1984. Microscopic criteria for the determination of directionality of cutmarks on bone. American Journal of Physical Anthropology 65, 359–366; Bromage, T.G., Bermudez de Castro, J.M., Jalvo, Y.F., 1991. The SEM in taphonomic research and its application to studies of cutmarks generally and the determination of handedness specifically. Anthropologie 29, 163–169]. Our data indicate that the methodology proposed by Bromage and colleagues can yield accurate results in an experimental setting. However, considering the complexity of uncontrolled (i.e., non-experimental) human butchery, we question the method's efficacy for investigating the antiquity of human handedness as potentially recorded in the zooarchaeological record. Our results highlight the limitations of current approaches, but it is hoped that they will also stimulate new, more productive techniques that use the archaeological record to discern the development of human handedness and its evolutionary significance.