Lithic use-wear analysis of Lupemban Middle Stone Age core-axes from Kalambo Falls, Zambia

Abstract

The evolutionary significance of the regional Middle Stone Age (MSA) Lupemban industry is explored by applying macroscopic lithic use-wear analysis to a securely stratified sample of core-axes from Kalambo Falls (Zambia). Radiometrically dated to ~ 265 ka BP (Twin Rivers, Zambia), the Lupemban is associated with the first sustained hominin settlement of the Central African woodland and rainforest belt. In this context, the development of sophisticated composite technologies bears directly on longstanding debates about the origins of behavioural and cognitive complexity in early Homo sapiens. The composite heavy-duty woodworking function historically proposed for Lupemban core-axes is a testable hypothesis that bridges the issues of hafting and woodland resource exploitation, which together underpin the industry’s purported evolutionary significance. Kalambo Falls provides the only stratified sample of Lupemban implements from Central Africa. Examination of 115 core-axes however reveals the overall condition of the collection is poor, and that a range of post-depositional surface alterations means neither microscopic traces nor residues are preserved. Functional interpretations thus necessarily rest on the patterning of macroscopic damage. Nineteen artefacts in good condition were identified and subjected to detailed analysis. Their comparison with a 245-piece experimental reference collection including 81 replica core-axes used both hafted and handheld for chopping and adzing wood, and for digging activities, reveals that only two Lupemban core-axes have clear traces, and these are consistent with heavy-duty contact on medium-hard contact materials; a hardness range that includes wood. Digging is not supported but other potential functions cannot be excluded. Direct hafting evidence is absent. This first glimpse into Lupemban core-axe function highlights the extreme difficulty of deriving high-resolution behavioural inferences from the Central African MSA record.