Two recently announced finds from Africa may strengthen the argument that humans were well on their way to complex, symbolic thinking by 75,000 years ago--long before the "creative explosion" of painting and jewelry began 40,000 years ago in Europe.
In the 16 April issue of Science, a team led by Christopher Henshilwood of the University of Bergen in Norway describes what they call the world's oldest beads: perforated snail shells. The team recovered the beads from a Middle Stone Age layer at Blombos Cave in South Africa that has been dated to about 75,000 years ago. That would make them more than 30,000 years older than any previously discovered personal adornment.
The other beads, two carved doughnut-shaped pieces of ostrich shell, come from a Middle Stone Age deposit extending to 110,000 years ago. They were found almost 4 years ago in Tanzania's Serengeti National Park but were announced only last month at the Paleoanthropology Society meeting in Montreal.Scientists say both are important discoveries, assuming they're actually that old. "If the dates hold up," says archaeologist Randall White of New York University, "we now seem to be seeing a trail of representational objects that is increasingly older as we move back [from Europe] into Africa." Henshilwood and others point to this small but growing record of earlier artistic objects from Africa as evidence that modern behavioral traits, such as the use of external symbols, developed gradually over a couple of hundred thousand years, not suddenly after our ancestors emerged from Africa, as some archaeologists have proposed.Not everyone finds the Blombos beads so persuasive. White, for example, is not convinced that humans made the holes in the snail shells. "I'm disturbed by the fact that there are no tool traces," he says. Henshilwood counters that the holes were "almost certainly" made by a "sharp stone point" and that worn areas on the lips of the holes could only have come from being suspended on something.As for the ostrich eggshells, their beadlike nature is beyond doubt, but their age is not. Part of the uncertainty stems from the fact that there were only two of them, 35 millimeters across; small objects can easily get mixed into lower layers. Although the researchers say that the geology puts the beads in a layer that ranges from 45,000 to 110,000 years old, the only way to be sure of their age would be to carbon date them--but that would destroy them.