The presence of beads, whether used as trade items, to convey group status, or to identify group members or relationships within a group suggests some form of language existed, says Henshilwood, who is affiliated with the University of Bergen, Norway, and the State University of New York.
"What the beads might symbolize is unknown, but it does imply that there had to be some means of communicating meaning, which plausibly is language," Henshilwood said. "Everyone knew what it meant, just as today if you're wearing Gucci sunglasses or a diamond tennis bracelet, there's a message being put out."
Recent studies have suggested that Khoisan, a southern African language that includes many clicks, could be as many as 100,000 years old. It's possible the people at Blombos were speaking in some form of click language, Henshilwood said.
Weighing the Evidence
When is a bead a bead? The two ostrich-eggshell beads found at the Serengeti site are unquestionably beads, but questions pertaining to the accuracy of their dating at 70,000 years old remain. By contrast, the date of the Blombos artifacts is fairly certain, but some question exists as to whether they are actually beads.
"The photographs [of the Blombos beads] look pretty convincing, but I'd like to see them in the flesh," Bower said. "A lot of shells like that have perforations, where they've been dropped by seagulls or occur through natural agencies. I'm cautiously convinced; it doesn't surprise me they occurred in a middle Stone Age context, since we found [beads] in Serengeti also."
Richard Klein, an anthropologist at Stanford University who has worked extensively at dig sites in South Africa, is a major proponent of the idea that modern behavior appeared rapidly, around 45,000 years ago, possibly as the result of a genetic change that facilitated our use of language. He is not convinced that the shells found at Blombos are actually beads.
"The holes are irregular and look fresh," Klein said. "We need to know why [the investigators at the Blombos site] think they were made by human hand and how they think they were madewere the holes punched out, did they file them, were they drilled out? Shell beads are very common in late Stone Age coastal sites, and you can see they're clearly modified as beads.
"There are ten sites in South Africa that have been excavated, and at only one do we find this kind of evidence for precocious behavior. I don't think the case has been clearly made yet that these are beads."
Klein also notes that the history of archaeology is littered with examples where later deposits of archaeological artifacts have slumped into older layers.
The isolated finds from middle Stone Age sites in Africa, even if correctly dated, don't necessarily indicate widespread "modern" behavior.
"You could have the prehistoric equivalent of a Michelangelo," Klein said. "An individual far ahead of his time, able to come up with innovative ideas that the rest of society doesn't adopt."
The Coastal Advantage
Henshilwood has a different theory to explain why evidence of symbolic thinking or "modern" behavior shows up in only some of the middle Stone Age sites, rather than all of them.
"The answer could be that it's not a behavior that's necessarily required everywhere," he says. Early modern humans living in a region with plenty of land animals, for instance, wouldn't be motivated to develop specialized tools to catch fish.
In addition, Henshilwood thinks the people at Blombos may have had a nutritional advantage. "We know today that fish is brain food," he said. "It's possible that people living in coastal regions just had a lot more going on. Remember, modern humans followed the coastline and reached Australia about 60,000 years ago, and they had to figure out how to build a boat to get there."
He says the "creative explosion" that took place around 45,000 years ago could be merely the result of facing new environmental and social pressures. Such pressures might have included an increase in population and competition with other species outside of Africa, like the Neandertals, who had occupied Europe for several hundred thousand years.
"I hate the use of the word 'modern,'" Bower says. "Modern behavior is talking on the telephone. Clearly that's not what humans were doing a hundred thousand years ago. Emerging evidence suggests that aspects of human technology are now strung out way back in time. Blombos has bone pointsyou have the famous bone harpoons at Katanga [dated to about 90,000 years old]long before the creative explosion of 40,000 to 45,000 years ago.
"I'm inclined to think we should get rid of the whole concept of 'modern' behavior," Bower said.
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