Wednesday
Jan292014

Assessing the Accidental Versus Deliberate Colour Modification of Shell Beads: a Case Study on Perforated Nassarius kraussianus from Blombos Cave Middle Stone Age levels

Personal ornaments represent a behaviour specific to humans in which items are displayed on the physical body to project meaning that can be interpreted by members of the same and possiblyother groups. For this reason, early instances of bead use are commonly interpreted as evidence for the existence of symbolic communication systems created by human societies comparable to ours. Colour plays an eminent role in beadwork. Colour modifications are reported on early shell beads from Middle Stone Age sites. However, identifying the colouring agent and demonstrating the intentional nature of the colouring process is not straightforward.

The presence of pigment residues on many well-preserved shell beads from Middle Stone Age (MSA) and Middle Palaeolithic (MP) sites suggests that colour may have played a role in the way early beadworks conveyed meaning. Dark grey to black colouring, interpreted as due to heating, has been observed on marine shell beads from the MSA at Blombos Cave and Sibudu in South Africa, at Grotte des Pigeons, Rhafas and Ifri n’Ammar in Morocco. However, the question of whether controlled use of fire was applied to change the colour of beads remains open. In a recent paper, avaialable online in the journal Archaeometry, Francesco d’Errico, Marian Vanhaeren, Karen Van Niekerk, Chris Henshilwood, and Rudolph Erasmus, combine microscopic, Raman and EDAX analyses of experimentally heated Nassarius kraussianus shells, dark Nassarius kraussianus shells from modern thanatocoenoses and Middle Stone Age Nassarius kraussianus shell beads from Blombos Cave to identify firm criteria to distinguish heated from unheated Nassarius kraussianus beads, and show that the dark colouring of the latter is due to heating.

Methodologically innovative, the results of their research are however unable to formally demonstrate that the heating of the Nassarius kraussianus was the consequence of a deliberate process seeking to produce dark ornaments. In order to verify this hypothesis, future research will need to focus on high-resolution analysis of the site formation processes to evaluate the degree to which the spatial distribution of small items such as Nk  shells may have been affected by syn- and post-depositional displacement.

d’Errico F., Vanhaeren M., Van Niekerk K., Henshilwood C.S., Erasmus, R. 2014. Assessing the accidental versus deliberate color modification of shell beads. A case study on perforated Nassarius kraussianus from Blombos Cave Middle Stone Age levels, Archaeometry, DOI: 10.1111/arcm.12072.

http://onlinelibrary.wiley.com/doi/10.1111/arcm.12072/abstract

PrintView Printer Friendly Version

EmailEmail Article to Friend

« Blombos Cave Still Bay artefacts feature on new set of South African cultural heritage stamps | Main | Non-destructive analysis of archaeological ochre: A preliminary application to the Middle Stone Age site of Diepkloof Rock Shelter (South Africa) »