When less is more: risk, reward and optimisation in Acheulean handaxe manufacture and the impact of skill

Abstract

As the most numerous manifestations of technology across the Palaeolithic record, linking stone tool artefacts to past hominin cognition and expertise represents a major pursuit of human origins researchers. Acheulean handaxes are of special interest as the earliest tools with clear design modalities, along with their presence spanning major evolutionary events of the Homo genus between 1.8 and 0.2 million years ago. Prior knapping experiments have evidenced the prolonged learning-trajectories necessary when replicating later Acheulean biface forms, with novices producing characteristically thick, irregular and asymmetric tools, most similar to early Acheulean assemblages. Here, we track 88 handaxe reductions by expert and novice knappers, detailing discrepancies not only in their final configuration, but in their patterns of change across rough-out and finishing stages. Extensive flaking (past the rough-out stage) improved expert handaxes but led to an accumulation of knapping errors and edge degradation for novices, providing incentive for the latter to adopt conservative flaking strategies. Simply, novice knappers should stop earlier during handaxe-shaping sequences, to maintain working edges and minimise the opportunity for breakages, edge crushing, and other major errors. This scenario presents a conflict between the immediate goals of tool use and long-term trajectories in skill acquisition; risk-aversion can yield short-term benefits but will hinder expansion of the technological repertoire. We suggest that the expertise required to produce bifaces characteristic of the later Acheulean required a greater propensity to incur short-term costs whilst knapping, facilitating long-term benefits in skill development.