Excavators say they've found tools made by chimps
Crude hammers likened to those of race of hominids
David Perlman, Chronicle Science Editor
Tuesday, February 13, 2007
Archaeologists working in the rain forest of West Africa's Ivory Coast say they have found a site where prehistoric families of chimpanzees fashioned crude stone hammers to crack open nuts for their food. The flaked stones made by those savvy animals at least 4,300 years ago are remarkably similar, the scientists said, to those made by the earliest known prehuman tool-users -- the race of hominids known as Australopithecines, whose fossils show they lived some 2.5 million years ago or more. The chimps, therefore, must have shared "cultural attributes" with the hominids who lived and went extinct almost at the start of the long and complex human lineage, said Julio Mercader an archaeologist at Canada's University of Calgary. Perhaps, Mercader speculated, the hominid race known as Australopithecines and ancient ancestors of tool-making chimps inherited their jointly shared "technology" from some common ancestor before the apes and human lineages split 6 to 7 million years ago. His conclusions, reported today in the Proceedings of the National Academy of Sciences, are already controversial. Tim White, the noted Berkeley paleoanthropologist who has long explored human evolution in Africa, insists, for instance, that it's impossible to tell just who or what made the scattered stones found by Mercader's group. Nicholas Toth, an Indiana University anthropologist who specializes in the study of Stone Age tools, sharply criticized earlier reports from Mercader's team -- published in the journal Science in 2002 -- suggesting that the chimp tool-makers might have imitated the earliest hominids. At least this time, Toth said, the team is "not overstating the case that there's chimp archaeology out there -- although whether the tools are chimp or human is still uncertain." Mercader and his international team of scientists explored three sites about 200 yards apart in the Ivory Coast's Tai National Park, and said they found a total of 210 flaked and chipped stone hammers made from granite, quartz or quartzite. Almost all were at a single site called Noulo, where the scientists found cracks in what they identified as stone hammers that bore traces of starchy pulp from edible nuts. The starchy pulp is evidence, they said, that to obtain food the apes had deliberately cracked open the nuts by bashing them with their hammers against tough tree roots or fallen tree limbs that they used as anvils. The rocks, most of them about the size of melons, clearly resemble the deliberately crafted choppers and hammers typical of the earliest Stone Age tools known to anthropologists as the Oldowan technology, Mercader said. But they were almost surely made by chimpanzees, he maintained, because the chipped rocks are too large to have been crafted by smaller human hands. He conceded there is no evidence that the chimps crafted them deliberately, however, and said humans too may have lived in the rain-sodden forest there, or at least passed through. "The tools represent a parallel Chimpanzee Stone Age," the archaeology team wrote in its report, and the chipped rocks indicate that chimps and the oldest hominid toolmakers of the distant past shared a culture that dates back for countless millennia. Since the chipped stones that the group has analyzed have been independently dated as at least 4,300 years old, and since mother apes in the region today are also known to teach their children to use stone tools, it is clear that nut-cracking behavior has now been passed along from parents to offspring for at least 200 generations, Mercader said. "I believe that the culture of these chimps dates back for many more generations than that," Mercader said, "and perhaps back to the time when they sprang from a common ancestor."
At Berkeley, White was strongly skeptical. The stone objects strewn beneath the trees at the reported sites seem little more than rubbish, he said. "The (team's) paper falls short of establishing that this thin scatter of rubbish was left by chimpanzees," White wrote in an e-mail. "An alternative hypothesis is that the rubbish was authored by humans." Toth, the Indiana anthropologist, is the founder and co-director of the Stone Age Institute at Bloomington, where he demonstrates how he can skillfully craft the hammers, sharp knives and spear points that evolution enabled the forebears of Homo Sapiens to make long before the dawn of true humanity. For the past 17 years, in fact, Toth has been teaching a smart bonobo named Kanzi -- a pigmy chimpanzee -- to make tools of all types from all kinds of materials as a way of understanding how chimp minds work. Toth is well aware how tricky it can be to identify stone objects that may or not be tools. In fact, he said in a telephone interview, only last year he was in San Francisco with Berkeley friends and colleagues, and at the rock-strewn base of Telegraph Hill they found a scatter of rough stones that had obviously been chipped and flaked merely by bumping against each other as they tumbled down the hill's precipitous slope. "You can find stones that have been broken either naturally or humanly, and they really look like tools," Toth mused. "But chimp archaeology is very new, and it needs a lot more study."Labels: anthropology
