Influence of Handaxe Size and Shape on Cutting Efficiency: A Large-Scale Experiment and Morphometric Analysis

Abstract

Handaxes represent one of the most temporally enduring and geographically widespread of Palaeolithic artifacts and thus comprised a key technological strategy of many hominin populations. Archaeologically observable variation in the size (i.e., mass) and shape properties of handaxes has been frequently noted. It is logical to ask whether some of this variability may have had functional implications. Here, we report the results of a large-scale (n = 500 handaxes) experiment designed to examine the influence of variation in handaxe size and shape on cutting efficiency rates during a laboratory task. We used a comprehensive dataset of morphometric (size-adjusted) shape variables and statistical methods (including multivariate methods) to address this issue. Our first set of analyses focused on handaxe mass/size variability. This analysis demonstrated that, at a broad-scale level of variation, handaxe mass may have been free to vary independently of functional (cutting) efficiency. Our analysis also, however, identified that there will be a task-specific threshold in terms of functional effectiveness at the lower end of handaxe mass variation. This implies that hominins may have targeted design forms to meet minimal (task-specific) thresholds, and may also have managed handaxe reduction and discard in respect to such factors. Our second set of analyses focused on handaxe shape variability. This analysis also indicated that considerable variation in handaxe shape may occur independently of any strong effect on cutting efficiency. We discuss how these results have several implications for considerations of handaxe variation in the archaeological record. At a general level, our results demonstrate that variability within and between handaxe assemblages in terms of their size and shape properties will not necessarily have had immediate or strong impact on their effectiveness when used for cutting, and that such variability may have been related to factors other than functional issues.2

Occasional, obligatory, and habitual stone tool use in hominin evolution

“…The most commonly cited targets for improved diet quality are large vertebrate carcasses and large plant underground storage organs, resources nonhuman primates do not exploit systematically or in bulk . Experiments engaging professional butchers and others in the use of reproductions of LCTs rate those artifacts as highly effective . Few recent humans use stone tools to dig up roots and tubers, but before they acquired metal tools many of them used stone implements to carve digging sticks out of tropical hardwoods.…”

“…110 Experiments engaging professional butchers and others in the use of reproductions of LCTs rate those artifacts as highly effective. 111,112 Few recent humans use stone tools to dig up roots and tubers, but before they acquired metal tools many of them used stone implements to carve digging sticks out of tropical hardwoods.…”

Biometric variables predict stone tool functional performance more effectively than tool‐form attributes: a case study in handaxe loading capabilities

“…). Indeed, previous research has indicated that shape, size and symmetry (Key and Lycett ; Machin et al . ) have only limited impact on a handaxe's ability to be used as a cutting tool; at least until morphological ‘thresholds’ are reached (Key and Lycett ).…”

“…Indeed, previous research has indicated that shape, size and symmetry (Key and Lycett ; Machin et al . ) have only limited impact on a handaxe's ability to be used as a cutting tool; at least until morphological ‘thresholds’ are reached (Key and Lycett ). As experimentally confirmed elsewhere, however, some specific tool‐form attributes do have significant influences on stone tool performance (e.g., Clarkson et al .…”

“…; Collins ), while size, edge angle and potentially symmetry can influence the functional capabilities of Acheulean bifaces (Jones ; Key et al . ; Key and Lycett ; Machin et al . ).…”