New research has revealed that early humans in the Middle Paleolithic collected shells with naturally occurring holes in them so that they could string them into decorative necklaces. The endearing discovery (who doesn't like to think of archaic humans being chuffed with their calcium carbonate bling?) is published in the journal PLOS ONE.
Stacks of shells with natural perforations have long been associated with early human living quarters, with examples dating back as far as 160,000 years ago in areas of North Africa, South Africa, and the Eastern Mediterranean. To establish if these collections were collected for decorative use as necklaces, lead researchers Daniella Bar-Yosef Mayer of Tel Aviv University and Iris Groman-Yaroslavski of the University of Haifa, Israel collected perforated clamshells (Glycymeris) and used various techniques including sand, leather, and stone to simulate the effects of wear over time as well as stringing them on wild flax. They were looking for indicators that they could potentially identify in ancient shells that would reveal they had also been strung in this way.

They compared their treated shells to some found in the Qafzeh Cave, a Mediterranean Paleolithic site dated to 120,000 years ago that contained lots of naturally perforated shells. Microscopic analysis of the Qafzeh Cave’s five best-preserved shells revealed traces consistent with the shells that had been superficially treated in the simulation, indicating contact with both string and shell-to-shell contact that suggests the shells were hung close together. Of the five shells, four also showed traces of ochre, which was sometimes used as a coloring treatment by early humans.
Evidence that the shells were hung on a string doesn’t mean we can determine the exact symbolic meaning of these shell beads, but bivalve shells including the clams from the Qafzeh Cave are a frequent hallmark across Paleolithic sites, which the researchers state indicates they held some importance. The inclusion of flax string also suggests that it was important that the shells were worn rather than just being a feature of the cave.
"Modern humans collected unperforated cockle shells for symbolic purposes at 160,000 years ago or earlier, and around 120,000 they started collecting perforated shells and wearing them on a string,” said Mayer in a statement. “We conclude that strings, which had many more applications, were invented within this time frame."