Unlike their chimpanzee cousins, bonobos — formally known Pan paniscus to the chimps’ Pan troglodytes — have shown limited toolmaking ability, and are better known for their relatively gentle, highly amorous natures. Yet that doesn’t mean bonobos are intrinsically incapable of tool use, which anthropologists consider to be a crucial cognitive benchmark. Their potential may simply have gone untapped.
Roffman and colleagues worked with Kanzi and Pan-Banisha, a pair of bonobos living at the Great Ape Trust, who in the 1990s had been taught to shape tools from flint. In the new study, published Aug. 21 in Proceedings of the National Academy of Sciences, the two bonobos are described using those techniques decades later to crack open food-filled logs used as research substitutes for marrow-rich bones.
Holding a flint core in their right hands and hammer stones in their left, both bonobos made small, sharp-edged scrapers. Kanzi, the handier of the pair, also made choppers, wedges and drills. Altogether, his toolset resembled the famous implements made 2.6 million years ago by ancestral dwellers of what is now the Olduvai Gorge in Tanzania. Indeed, the marks left by Kanzi’s tools on his logs were strikingly similar to wear patterns seen in ancient butchered bones.
“Only early Homo was thought to produce such tool use markings,” wrote Roffman’s team. “Here we report that present-day Pan also has such competencies.”
“What is interesting here is that they use these tools for specific actions that could have been performed by our ancestors, like digging for food underground or extracting bone marrow,” said primatologist Thibaud Gruber of Scotland’s University of St. Andrews, who also studies bonobo tool use. He called the results “an important finding,” underscoring the likelihood that the last common ancestor of bonobos, chimps and humans possessed toolmaking abilities.
As Gruber and the study’s authors pointed out, Kanzi and Pan-Banisha are no ordinary bonobos. Aside from their tool-making training, they’ve lived around humans their entire lives, and use pictorial symbols to engage in complex dialog with their human handlers. Kanzi and Pan-Banisha’s level of toolmaking sophistication probably doesn’t exist in wild bonobos.
Yet rather than being a caveat, that may be a central lesson of the results, said primatologist Sue Savage-Rumbaugh, a study co-author and head scientist at the Great Ape Trust. Other bonobos can make stone tools, but it’s these two individuals, whose vocabulary includes 480 word symbols and who understand thousands of English words, who make tools best.
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According to Savage-Rumbaugh, present-day Pan, both bonobos and chimpanzees, possess that cognitive advance. Whether it’s readily apparent is simply a function of circumstance. “The proper cultural and ecological conditions could serve to bootstrap a complex stone tool technology in Pan,” she said.
Findings like these drive home the importance of protecting chimpanzees and bonobos, which in the wild are going extinct, said Roffman. We’re literally preserving a living piece of our own heritage. “We have looked to the stars searching for contact with intelligent beings,” he said. “However, they have been with us all along, and are called Pan.”