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Chimps Shown Using Not Just a Tool but a "Tool Kit"

Bijal Trivedi
for National Geographic News
October 6, 2004
 
Anyone who has tried to replace a punctured tire or fix a leaky faucet knows the importance of having the right tool for the job. Chimpanzees, it turns out, are also very particular about their tool choice, especially when it comes to digging into termite mounds to get a tasty snack.

Using infrared, motion-triggered video cameras, researchers have documented how chimpanzees in the Goualougo Triangle—a region within the Nouabalé-Ndoki National Park in the Republic of Congo—use a variety of tools to extract termites from their nests. The "tool kits" are among the most complex ever observed in wild chimp populations.

See Chimp Video Clips (Real One Player Required)
Video 1: Adult Female Punctures Termite Nest With Stick
Video 2: Young Male Punctures Nest, Then "Fishes"
Video 3: Adult Female Punctures Aboveground Nest, Then "Fishes"

Videos courtesy The American Naturalist



Tool use among chimpanzees is well documented. For example, chimps in the Taï rain forest, in West Africa's Côte d'Ivoire, use stone "hammers" to crack open nuts. In Tanzania's Gombe National Park, chimps use straw and blades of grass to hunt for termites, as made famous in Jane Goodall's classic documentaries.

The new study, published in the current issue of the biology journal The American Naturalist, adds another detail to this picture.

For the last two decades scientists in the Congo River Basin have been collecting sticks—tools discarded after termite fishing—around termite mounds. But few have witnessed the chimps in action.

The new video cameras revealed chimps using one short stick to penetrate the aboveground mounds and then a "fishing probe" to extract the termites.

For subterranean nests the chimps use their feet to force a larger "puncturing stick" into the earth, drilling holes into termite chambers, and then a separate fishing probe to harvest the insects. Often the chimps modified the fishing probe, pulling it through their teeth to fray the end like a paintbrush. The frayed edge was better for collecting the insects.

"It's exciting to watch these chimps do something that we've seen only people do before—use their feet to push the stick into the ground as a farmer might do with a shovel," said Pat Wright, a primatologist with the New York State's Stony Brook University.

Termite Hunting, Tough Act To Follow

The chimps use one particular tree species—Thomandersia hensii—to fashion their puncturing sticks and an herb—Sarcophrynium spp.—for their fishing probes.

The preference for these trees suggests that chimps not only know which raw materials are best suited for each task but also travel to seek them. The chimps arrive at the termite nests with the appropriate tools in hand, said co-author Dave Morgan, a conservationist with Cambridge University in the U.K. and the Bronx-based Wildlife Conservation Society in New York.

Termite fishing is much tougher than one might think, said co-author Crickette Sanz, an anthropologist at Washington University in St. Louis, Missouri. Sanz and Morgan both tried fishing for the insects.

After cracking through the sunbaked mounds or subterranean chambers with twigs or sticks, fashioning a good fishing probe is a challenge. The chimps even use special techniques for pulling the aggressive soldier termites off the end of the probe. "We were less successful than most of the [chimp] youngsters—this is a complex skill that is developed with years of practice," Sanz said.

The video showed infants watching closely as mother chimps skillfully extract sticks swarming with large, shiny black termites. Through these social interactions, tool-using behaviors and techniques are passed from one individual to the next—what many scientists believe to be the hallmark of culture.

The research was funded in large part by the National Geographic Society's Expeditions Council and the Wildlife Conservation Society.

New Technology Better for Chimps

Both the findings and the methods used to conduct the research are novel, said Agustin Fuentes, an anthropologist and primatologist at the University of Notre Dame in Indiana, who reviewed the research. "This is the first time we have seen chimps using multiple tools for a single task," he said.

The other noteworthy feature is the technology—motion-triggered cameras—Sanz and Morgan used to spy on the chimps at six termite mounds.

"The videos are very impressive—121 examples of chimps using more than one tool at termite mounds. These chimps are in one of the most remote rain forests in the world. No one has ever viewed them so closely—the results are very exciting and very new," Wright said.

At other study sites in Africa, like Jane Goodall's famed Gombe site, the chimps are habituated to humans. "At Gombe, there are at least one or two people who follow the chimps around their entire lives. So that's got to have some sort of impact," Fuentes said. "Sanz and Morgan used video analysis to minimize the impact on the chimps and bypass the habituation."

But as the cameras were watching the chimps, the chimps were also inspecting the cameras. Many of the apes stopped in their tracks when they first saw the camera units—but the responses were very different between individuals. Some immediately retreated. Others walked right up to the camera and peered into the lens.

Close Encounters With a Camera

One infant gained a little more courage with each visit to the nest. The first time he saw the camera, he approached and looked into the lens. The second time, he sat in front of the camera and tried to press his finger through the glass. On his third visit, he tried to insert a puncturing tool into the lens.

"We were very humored and a bit worried during his last visit, when he brought another infant to inspect the camera," Sanz said.

The cameras were the brainchild of electrical engineer Steve Gulick, director of Wildland Security, a Brooklyn-based organization that develops antipoaching technology. Gulick often lends his talents to conservation projects.

When Gulick heard what Sanz and Morgan wanted to study, he rigged up a single camera near a termite mound. The camera worked well, and five additional cameras were fixed within a 100-square-kilometer (40-square-mile) radius.

The study reinforces the notion that tool use began long before humans walked the planet. Humans, chimps, and orangutans all used wood and bone tools, suggesting that tool use originated with a common ancestor more than 12 million years ago, Fuentes said.

The researchers are expanding their camera array to more chimp communities to observe differences in tool use.

There is tremendous pressure to document these chimpanzee cultures quickly. The animals are endangered by a burgeoning trade in their meat and outbreaks of viruses such as Ebola. The forests in which they reside are threatened by logging interests.

"Humans are extraordinary tool users. Examining these behaviors in our closest living relatives provides insights into the material culture and social traditions of our species," Sanz said. "As these forests vanish so do our opportunities to document the unique cultures that reside within them. We are quickly losing these apes that we hardly know."

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