Introducing Lithikos 2 - a novel volumetric morphometric analyser via a volume-based approach to handaxe refinement

This article describes a volumetric approach to the analyses of Acheulean handaxe refinement using Lithikos, an open-access morphometric application, as an alternative to traditional linear analyses of stone tool shape. Lithikos quantifies handaxe refinement using an artefact model’s volume, surface area and elongation instead of conventional ratios of linear distances like maximum breadth and thickness. A pilot study of 399 handaxes from five Levantine assemblages representing over 1 million years of Acheulean creativity demonstrated that this novel high-resolution coefficient may offer greater ecological validity, measurement sensitivity and practical utility compared to traditional linear coefficients such as Bordes Flatness Index and Roe’s Refinement Index. A low-resolution volumetric extension of Roe’s Refinement Index is also introduced to confirm the morphometrical characteristics of the volumetric refinement index as well as a size-controlled version of the coefficient. By explicitly incorporating allometric scaling, the VRI may provide a dimensionally coherent metric that outperforms traditional linear ratios of handaxe refinement. Putative factors underlying the results as well as potential analytical extensions of the volumetric refinement index are discussed.