What is a ‘Giant’ Handaxe? Ergonomic Thresholds, Functional Impacts and Acheulean Social Signalling Potential

‘Giant’ handaxes are a widely recognized but infrequently investigated phenomenon of the Acheulean period. The scale of their distribution and the selective pressures underpinning their production are not well explored. Here, we report new data from a large-scale experimental study that identifies the point at which handaxes become too large to use with a single hand, alongside a review of known Acheulean assemblages displaying ‘giant’ handaxes. On the understanding that most ‘regularly sized’ Acheulean handaxes were gripped in one hand, if handaxes require bimanual grips, alternative explanations for their production—beyond unimanual butchery and woodworking tasks—should be sought. Our data identify clear mass, length and thickness thresholds for bimanual gripping. It is revealed that spatially and temporally diverse archaeological sites display ‘giant’ artefacts that exceed these thresholds. We suggest these atypically large handaxes would most plausibly have been utilitarian tools used for cutting, but in alternative ways to more regularly sized bifaces. This includes when worked materials were secured by another individual or structure, during digging activities, or when used as a stationary cutting ‘plane’ secured on the ground.