These days, diamonds are a girls best friend. But more than 70,000 years ago it seems that tick shells were the jewelry of choice. Researchers report today in the journal Science the discovery of the oldest known decorative beads. According to team leader Christopher Henshilwood of the University of Bergen in Norway, the find "provides important new evidence for early symbolically organized behavior in Africa."

The international team of researchers uncovered 41 shell beads, which date to 75,000 years ago, in Blombos Cave in South Africa. The pea-size shells (see image) seem to have been selected based on their dimensions, the team reports, and were deliberately perforated. What is more, because the creatures from which they came (Nassarius kraussianus) are waterborne and the cave is located 20 kilometers from surrounding estuaries, Middle Stone Age humans had to deliberately transport them. The shells were clustered in groups of up to 17 and the scientists suggest that each grouping could have come from a different jewelry item. They also detected traces of red ochre, a widely-used pigment at the time, on many of the spheres.

A number of previous discoveries indicate that humans began to rely on symbolism about 40,000 years ago. But the new finds, together with two pieces of engraved ochre from the same South African cave recovered last year, suggest that this ability may have developed much sooner. Some questions remain--such as just how the holes were made in the shells--but recovering more relics from the time period should help scientists better understand our Stone Age predecessors. Notes Henshilwood, "Once symbolically mediated behavior was adopted by our ancestors it meant communication strategies rapidly shifted, leading to the transmission of individual and widely shared cultural values--traits that typify our own behavior."