Pierced or perforated: Using 3D models to differentiate anthropogenic piercing from natural perforations in shells

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• Marjolein Bosch, Austrian Academy of Sciences
• Friday 20 May 2022, 13:15-14:00
• Online through zoom.

If you have a question about this talk, please contact Ruairidh Macleod.

Perforated shells are often used to study socially mediated behaviour in past hunter-gatherer groups. The assumption is that their exclusive symbolic function makes them ideally suited to investigate social networks, dispersal activity, and social interaction. Before making any statements regarding human behaviour however, it needs to be established whether perforated shells from archaeological assemblages were used as personal ornaments. One of the key issues regarding beach-collected marine taxa is whether beached specimens were purposefully collected, e.g., preferential selection of naturally holed specimens, or whether human-made perforations may be identified. I will present a novel approach using μCT scans of pristine shells to create three-dimensional models of shell thickness. Models of two species, Tritia (Nassarius) gibbosula and Columbella rustica, are used to map robust and fragile zones on shells. The hypotheses being that structurally weak zones would be prone to natural perforations and that damage within these zones should be random. To test these hypotheses, heat maps of shell density are used to compare perforation locations in modern-death and archaeological assemblages. The results show that in natural death assemblages both hypotheses are indeed met. Whereas in the archaeological samples from early Upper Palaeolithic contexts at Ksâr ‘Akil (Lebanon), perforation locations in C. rustica are less variable and more frequent in robust zones. Perforations in T. gibbosula mainly occur in structurally weak zones, but their distribution within these zones is not random and favours locations facilitating easy suspension. This suggests that humans used both species as beads, by selecting shells with natural perforations in specific locations, by perforating the shells themselves, or using a combination of both methods. This in turn, warrants investigations into the social and behavioural implications of their presence.

Registration link: https://cam-ac-uk.zoom.us/meeting/register/tJMqcuGupz0pHt1vL-6yil0-ZSESaL4gT9sp

This talk is part of the Pitt-Rivers Archaeological Science Seminar Series series.

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• AUB_Cambridge Seminars
• Online through zoom
• Pitt-Rivers Archaeological Science Seminar Series

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