Washington, DC — New discoveries made by archaeologists at Blombos Cave high on a limestone cliff above the Indian Ocean are challenging a long-held theory that modern human behavior originated in a "creative explosion" in Europe 40 - 50,000 years ago.
"There is a growing amount of evidence that has been coming out over the last 10 years that modern man began much further back in time in Africa," says Dr. Rick Potts, director of the Human origins program at the Smithsonian Institution in Washington, DC.
Finds at Blombos, about 200 miles east of Cape Town, South Africa, seem to show that 70-90,000 years ago, human cave-dwellers were turning animal bones into decorated, sophisticated tools and finely-worked weapon tips using skills more advanced in concept and application than are typical of the stone tools usually found in this period. These shaped tools are among the oldest found in Africa; they are made in a style that has only previously been seen in Europe where it is estimated that similar tools are approximately 20,000 years old.
Also found are what researchers describe as "awls" that might have been used to pierce leather to make clothing and bags. These middle stone age people trapped a wide variety of animals.
Some of the artifacts discovered at Blombos were engraved with symbolic marks, "reflecting," says Dr. Potts, "an ability to symbolize which hints at language, abstract thought. It's something we've been waiting for."
In a report to be published in the January issue of the Journal of Evolution, Dr. Christopher S. Henshilwood of the South African Museum presents an analysis of 28 bone tools and other artifacts found at Blombos. The report also analyses 8,000 pieces of iron ochre that might have been used for body decorations of a kind similar to those still used by the Masaai and other peoples of Africa.
In a 1999 article in the South African Museum's newsletter, Dr. Henshilwood described the people occupying this area as "anatomically modern homo sapiens" living off "bountiful sea and land" 90,000 years ago. "But, most importantly, these people left evidence of human skills and behaviour unprecedented at this time - even on a global level. In essence, the Blombos Cave inhabitants were behaviourally 'modern' at a time when Neanderthals still roamed Europe and the first H.sapiens were just making their way out of Africa."
The origins of modern human behavior are still the focus of intense debate, however. "This is really an issue that should be discussed in scientific journals," said Dr. Richard D. Klein, an anthropologist at Stanford University. Klein has argued that modern behavior and human language appeared suddenly 50,000 years ago as a result of a genetic mutation in the brain.
Klein, while admiring the work, is still skeptical about the Blombos conclusions because, he says, the tools are actually 2,100 years old. He thinks they have been lying in younger sediment and somehow migrated to where they were found. To justify the revised view, such tools ought to have been found in other parts of Africa and are have not been, says Klein. "Other sites show nothing like this."
Dr. Henshilwood and others working the Blombos site say the chemical content of the bones in the tools they've found is different than those in the younger sediment.
As for the supporting evidence in other parts of Africa, Dr. Potts says there was a "a gradual process toward modernity," citing finds on the use of ochre in central Kenya and the use of bone parts as fish hooks for catching catfish in what is known as the Katanga region of Congo: "It all seems to come together at Blombos."