More than 70,000 years ago, people occupied a cave in a high cliff facing the Indian Ocean at the tip of South Africa. They hunted grysbok, springbok and other game. They ate fish from the waters below them. In body and brain size, these cave dwellers were definitely anatomically modern humans.
Archaeologists are now finding persuasive evidence that these people were taking another important step toward modernity. They were turning animal bones into tools and finely worked weapon points, a skill more advanced in concept and application than the making of the usual stone tools. They were also engraving some artifacts with symbolic marks manifestations of abstract and creative thought and, presumably, communication through articulate speech.
The new discoveries at Blombos Cave, 200 miles east of Cape Town, are turning long-held beliefs upside down.
Until now, modern human behavior was widely assumed to have been a very late and abrupt development that seemed to have originated in a kind of "creative explosion" in Europe. The most spectacular evidence for it showed up after modern Homo sapiens arrived there from Africa about 40,000 years ago. Although there had been suggestions of an African genesis of modern behavior, no proof had turned up, certainly nothing comparable to the fine tools and cave art of Upper Paleolithic Europe.
"I used to accept the `creative explosion' concept for the origin of modern human behavior," said Dr. Rick Potts, director of the human origins program at the Smithsonian Institution. "Now I think the nails are going into the coffin of that hypothesis. We are seeing many elements of modernity that were developing much earlier, in Africa, and more gradually."
One reason Europe's prehistoric surge of creativity held the attention of scholars for so long was that it had virtually no serious competition. Archaeologists had spent little time digging African sites of that period, while every year in Europe they seemed to find more cavern walls adorned with painted deer, horses and wild bulls. Enthralled, scholars perhaps could not bring themselves to look for earlier and more distant origins of modern behavior.
But after more than a decade of controversy, the South African cave artifacts are now being generally accepted as the earliest evidence of such modern human behavior. If correct, these and other findings establish that Homo sapiens came out of Africa not only with fully modern anatomies, but also with at least 30,000 years of experience in modern behavior. Dr. Potts said the beginning of this gradual behavioral evolution might reach back more than 200,000 years.
Archaeologists have described the new research and their interpretations in recent seminars and journal articles. A group led by Dr. Christopher S. Henshilwood of South Africa is publishing a comprehensive report in this month's issue of The Journal of Human Evolution.
The report includes an analysis of 28 bone tools and other artifacts from Blombos Cave, as well as 8,000 pieces of the iron oxide mineral ocher that might have been used for body decorations.
Taken together with other recent finds in Africa, Dr. Henshilwood's team reported, the Blombos evidence "for formal bone working, deliberate engraving on ochre, production of finely made bifacial points and sophisticated subsistence strategies is turning the tide in favor of models positing behavioral modernity in Africa at a time far earlier than previously accepted."
Many other archaeologists specializing in human evolution said the new research seemed to dispel previous doubts about the antiquity of the artifacts, which have been excavated and argued about since some of the first pieces were collected in 1992. Skeptics had suspected that artifacts of more recent vintage had somehow intruded into the cave's lower and thus older sediments.
The oldest such tools reliably dated in Africa had been only 25,000 years old. The lineage of the first human ancestors is estimated to have diverged between five million and seven million years ago in Africa from the line leading to apes. Anatomically modern humans, Homo sapiens sapiens, evolved in Africa about 150,000 to 100,000 years ago.
In an interview by telephone from the cave site, Dr. Henshilwood said: "We're absolutely convinced of the dating of the tools. Analysis of them makes us confident that what we have is evidence of a bone-tool industry, not just occasional pieces."
Most of the bone tools are awls, probably for working leather. But the most impressive ones, archaeologists say, are three sharp instruments. The bone appears to have been first roughly shaped with a stone blade. Then it was finished into a symmetrical shape and polished for hours, most likely with a piece of leather and ocher powder. Some etched marks might have identified the owner of what were hunting spear points.
"Why so finely polished?" Dr. Henshilwood asked. "It's actually unnecessary for projectile points to be so carefully made. It suggests to us that this is an expression of symbolic thinking. The people said, `Let's make a really beautiful object.' "
Like many hunter-gatherer societies, archaeologists say, these cave dwellers might have made some of these tools for exchange in long-distance trading. Beauty added value to the object, perhaps a value with symbolic meaning.
As Dr. Henshilwood explained: "Symbolic thinking means that people are using something to mean something else. The tools do not have to have only a practical purpose. And the ocher might be used to decorate their equipment, perhaps themselves. That is a symbol of something else, which we don't understand. But it suggests that these people must have had articulate speech to conceive and communicate such symbolism."
Dr. Henshilwood is an archaeologist at the South African Museum in Cape Town and an adjunct associate professor at the State University of New York at Stony Brook. His co- authors are Dr. Francesco d'Errico of the Institute of Prehistory in Talence, France; Dr. Curtis W. Marean of the Institute of Human Origins at Arizona State University; Dr. Richard G. Milo of Chicago State University, and Dr. Royden Yates, also of the South African Museum.
Another archaeologist, Dr. Alison Brooks of George Washington University, who has reported finding other early examples of African toolmaking in Congo, called Blombos Cave "a tremendously exciting site."
Bone tools were indicative of modern behavior, Dr. Brooks said, because their production required a "higher level of planning and conceptualization than just knocking off flakes of stone." The toolmaker, she explained, had to have "a vision of the object in mind and be able to plan the creation of something complicated to solve a particular problem."
Not everyone is convinced that the Blombos discovery undercuts previous theories about the rise of sophisticated human behavior in Europe. Dr. Richard G. Klein, an archaeologist at Stanford University who has argued that human language and modern behavior appeared suddenly 50,000 years ago as a result of a genetic mutation in the brain, said he remained cautiously skeptical.
Dr. Klein said that he was still unconvinced that the bone tools had not originated in younger sediments and then migrated to the layer where they were found. And though he was impressed by the report of two pieces of ocher engraved in a crosshatched pattern, he questioned why, if the dating was correct, similar projectile points were not being found more widely in African sites.
Dr. Henshilwood and colleagues said that a thick layer of yellow sand separated the sediment layer in which the bone tools were found from a higher layer with evidence of human occupation only 2,000 years ago. No disturbances of this distinct break in the sediments, which could have allowed a downward movement of younger artifacts, were found in a recent re-examination of the cave, the archaeologists said.
Recent tests, Dr. Henshilwood said, showed that the chemical content of the bones in the tools was different from that of bones in the 2,000-year-old layer.
Dr. Marean of Arizona State University said that in the bone tools archaeologists were seeing a new picture of modern human evolution. "This puts the behavioral evolution in step with the anatomical evolution," he said.
File Date: 012.10.01