Reassessment of Anthropic Modifications on the Early Pleistocene Hominin Specimen Stw53 (Sterkfontein, South Africa)

Linear marks were observed on the maxillary zygomatic process of the early Pleistocene hominin fossil Stw53 from the Sterkfontein cave site. The taxonomic allocation of this specimen is still under debate, as it has been attributed either to the genus Homo or Australopithecus . Two alternative hypotheses have been proposed regarding the taphonomic agent responsible for the linear marks observed on this specimen. These modifications were initially assigned to anthropic cutmarks inflicted by stone tools, thus representing the earliest cutmarks discovered on hominin remains. Conversely, these linear marks were interpreted by others as non-anthropic modifications. In order to better understand the origin of the linear marks, a new taphonomic appraisal of these modifications was conducted using a multivariate statistical approach complemented by butchery and trampling experiments on extant mammal bones. This new study of Stw53 linear marks does not provide evidence for anthropic activities but, rather, supports the unintentional origin hypothesis.