for National Geographic News
Humans may have been wearing jewelry as far back as 75,000 years ago, about 30,000 years earlier than previously thought, if 41 shells found at Blombos Cave in South Africa prove to have been used as beads.
The shells are from a tiny mollusk, Nassarius kraussianus, that lived in a nearby estuary. They have perforations and wear marks consistent with being used as beads, according to scientists excavating the middle Stone Age site.
Beads are considered definitive evidence of symbolic thinking, which many scientists don't think occurred in modern humans until about 45,000 years ago.
"The beads add to a growing pile of evidence that humans acquired a suite of 'modern' skills much earlier than previously thought," says archaeologist Christopher Henshilwood, director of the Blombos Cave Project.
"There's more and more evidence that they could fish and hunt large mammals, and that they were making fine bone tools. When our ancestors left Africa, they were already modern, already thinking and behaving in many senses the way we do today."
Genetic and fossil evidence indicate anatomically modern humans emerged in Africa around 120,000 years ago. Whether modern behavior evolved gradually in tandem with anatomical modernity, or emerged suddenly around 45,000 years ago, has long been a bone of contention among anthropologists and archaeologists.
A great divide exists in the archaeological record. Waves of modern humans began leaving Africa to colonize the rest of the world around 45,000 years ago. There is extensive evidence that "modern behavior" existed in Europe around 40,000 years ago: cave paintings, jewelry, more elaborate burial rituals, and more specialized tools.
"A creative explosion took place sometime around 40,000 years ago that is strongly expressed in the archaeological record over a very large geographical area," said John Bower, an archaeologist-paleoanthropologist at the University of California, Davis. "The question is whether something happened to affect the architecture of the brain."
Until recently evidence of symbolic thinking at middle Stone Age (roughly 280,000 until 45,000 years ago) sites in Africa has been scant and hotly disputed. Two years ago the Blombos investigators reported finding sophisticated bone tools and two pieces of iron ore with abstract markings at the site.
The question is complicated by the fact that there is no real consensus on how to define "modern" behavior. However, the production of art or jewelry is universally accepted as an indicator of symbolic thinking.
"Beads are tangible evidence of a concept of self," Bower said. "You're not going to decorate yourself if you have no concept of self."
Bower is the project leader at Loiyangalani, a dig site in the Serengeti National Park in Tanzania. He and colleagues recently reported finding two ostrich-eggshell beads at the site that are tentatively dated to about 70,000 years old. The announcement was made at the annual meeting of the Paleoanthropology Society in March of this year.
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