Using morphometrics to reappraise old collections: The study case of the Congo Basin Middle Stone Age bifacial industry

Despite its strategic location within the continent, Central Africa is rarely integrated into the reconstruction of population dynamics during the Middle Stone Age (MSA) of Africa, especially in terms of the emergence, diffusion and behavioural patterns of Homo sapiens. However, hundreds of sites have been discovered in Central Africa during the 20th century and attributed to the Lupemban, one of the main MSA technological complexes of the region. This complex is mainly characterised by typological criteria based on the numerous bifacial pieces found in the Congo Basin and interpreted as an adaption to the rainforest environment. Most of these Lupemban assemblages have not been studied for decades and thus it is particularly difficult to assess their diversity. This paper presents a detailed combined morphometrical approach (linear measurements and indices, Log Shape Ratio, Elliptic Fourier Analysis) to take a fresh and rigorous look at the Lupemban bifacial tools. We discuss the comparison of different morphometrical approaches to deal with “old” collections for which contexts, particularly chronological ones, are partially missing. We present the results of this approach on three assemblages of bifacial pieces gathered in the 1930s and late 1960s. We quantify their variability and discuss not only their homogeneity but also the variation of a Lupemban hallmark, namely the “Lupemban point”.