A 4,200-year-old necklace made of alternating black and white disc-shaped beads has helped British researchers devise a new method for the identification of shell species in archaeological artefacts.
     Mollusc shells appear to have been among the first durable materials used for personal ornaments and building tools, but their often degraded condition makes it hard to identify the species with traditional analysis. York University's Beatrice Demarchi, Julie Wilson, and their colleagues used statistical pattern recognition methods and amino acid analysis to distinguish shells taxonomically.
     The new approach was tested on a necklace which has intrigued archaeologists ever since its discovery in 2009 at an early Bronze Age site near Suffolk in eastern England, in the grave of a young adult woman, radiocarbon-dated to around 2200 BCE. The necklace consisted of strings of tiny disc beads of shells and black jet, possibly carved out of the fossils of monkey puzzle trees from Whitby, 260 kilometres to the north.
     Alison Sheridan, principal curator of Early Prehistory at National Museums in Scotland, says "The necklace had not been worn on the body, but was found near the head. Beads of jet and shell alternated in a zebra design. Interspersed with these - and I am currently trying to work out exactly how the arrangement worked - were a number of amber beads, some perforated straight through, some with cross-shaped perforations."
     "The necklace design is unique, although a lot of Early Bronze Age jet jewellery, and some amber jewellery, is known," Sheridan adds, "However, the use of sea shells for jewellery during the Early Bronze Age in Britain is incredibly rare."
     It appears that Bronze Age craftspeople used local shells like dog whelk and tusk shells to make the necklace. Conical, curved and open at both ends, tusk shells resemble miniature elephant tusks, hence the name. Dog whelks are predatory, carnivorous sea snails often found on rocky shores. While dog whelks are abundant around the Suffolk coast today, tusk shells are less widespread, but present along the southern coast.

Edited from Discovery News (19 June 2014)