Perforations in Columbellidae shells: Using 3D models to differentiate anthropogenic piercing from natural perforations

• Published in: Journal of archaeological science, reports Vol. 49; p. 103937
• Main Authors: Bosch, Marjolein D., Buck, Laura T., Strauss, Andre
• Format: Journal Article
• Language: English
• Published: Elsevier Ltd 01-06-2023
• Subjects: 3D models; Columbella rustica; Ksâr ‘Akil; micro-CT scans; Personal ornaments; Shell beads; Taphonomy; Upper Palaeolithic; Ksâr ‘Akil; Shell beads; Personal ornaments; Upper Palaeolithic; 3D models; Columbella rustica; micro-CT scans; Taphonomy
• ISSN: 2352-409X
• DOI: 10.1016/j.jasrep.2023.103937

•New approach aids identification of personal ornaments in the archaeological record.•Columbella rustica shells were used as beads from the Initial Upper Palaeolithic on.•3D shell thickness models aid distinction of natural from anthropogenic perforations.•Columbella rustica and C. adansoni share overall shell-thickness distribution pattern.•Standardisation of perforation size suggests formal bead manufacture at Ksâr ‘Akil.
Perforated shells are often used to study socially mediated behaviour in past hunter-gatherer groups. One of the key issues regarding empty shells from beaches or fossil outcrops is determining human agency in the accumulation and modification of an assemblage. Here we investigate anthropogenic mediation in Initial Upper Palaeolithic and Early Ahmarian assemblages of Columbella rustica at Ksâr ‘Akil (Lebanon). We compare perforations in the archaeological specimens with data from newly gathered Columbellidae modern death assemblages from Tenerife (Spain) using three-dimensional shell-thickness models as templates. This approach, using micro-CT scans of pristine shells to map robust and fragile zones on shell outer-surfaces, allows us to contextualise the two datasets within their natural morphology. Our results show that in natural death assemblages the vast majority of perforations occur in structurally weak zones, and their distribution can be explained by shell morphology in combination with predator activity and other post-mortem damage. In our archaeological dataset we found a higher frequency of perforations in more robust zones and a higher uniformity in their location, size and shape. This suggests human mediation in either the selection or manufacture process of C. rustica beads at Ksâr ‘Akil from as early as the Initial Upper Palaeolithic and throughout the Early Ahmarian. Standardisation in perforation shape, size and distribution have been argued to be indicative of formalised manufacture processes and our results are thus more congruent with intentional bead manufacture than the selection of naturally-holed specimens.