Is the StW 53 cranium (Sterkfontein, South Africa) the earliest evidence of tool-assisted hominin modification? New data from a neotaphonomic experiment and the virtual reconstruction of its linear marks

Abstract

Taphonomic studies aim to discern the origin of bone assemblages at archaeological and palaeontological sites, determining whether (or the degree to which) carnivores, humans or natural processes were involved in the accumulation and modification of such assemblages. The StW 53 Australopithecus cranium from Sterkfontein (South Africa) exhibits striations on the antero-medial face of the zygomatic arch. Previous taphonomic analyses suggested that these bone surface modifications were cut marks. However, subsequent research argued that the linear marks were produced through contact with an autogenic clast from the cave. An accurate taphonomic interpretation is crucial because, if the StW 53 striations are cut marks, it could represent the earliest evidence of tool-assisted modification of a hominin bone. New neotaphonomic experiments have been conducted to test both hypotheses. Additionally, geometric morphometric analysis and machine learning algorithms have been used to characterize the morphology of both cut marks and natural marks. Results indicate that the more plausible hypothesis for the origin of the StW 53 striations is a natural taphonomic process involving an autogenic clast from the cave.