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Animal Behavior

Tool Time, Monkey Style
No nut's too tough for rock-wielding capuchins

Tool use was once touted as a key thing that separates human from beast. But in truth, lots of other animals use tools, from apes to birds to bugs. Recently scientists caught a glimpse of wild monkeys using tools in a surprisingly sophisticated way.

The monkeys, brown capuchins (Cebus apella), tool around in a remote dry forest in northeastern Brazil. After  laying tough-shelled palm nuts on sandstone slabs, the monkeys stand up—sometimes using their tails for support—raise rocks perhaps half their own weight head high, then slam the nuts. Not content with any old hammer, the monkeys will haul a favorite rock to the "anvil" site, says photographer Pete Oxford. They also place nuts in small pits from previous hammering and sniff them between strikes to see if the kernel is exposed yet. Older capuchins are the best nut crackers, but young ones also try their hand.

"These monkeys are acting in ways we once thought only apes did," says primatologist Dorothy Fragaszy of the University of Georgia, who plans to study the monkeys' tool use in detail.

And since capuchins are only distantly related to apes, she says, their ability must have evolved independently.

"Their Schwarzenegger dead lift is amazing to see," says Charles Munn, a zoologist with Tropical Nature (a nonprofit ecotourism group) who first learned of the hammer wielders from locals. "But it's no surprise the monkeys have to work hard to get food in such a marginal, scrubby habitat."

—Jennifer Steinberg Holland

Web Links

Brown Capuchin Monkeys$narrative.html
Partners of organ grinders and stars of film and television, capuchins are the most familiar New World monkeys. Read about their life in the wild at the website of the University of Michigan's Museum of Zoology.

Tropical Nature
Working with local communities and conservation organizations to locate, develop, and market outstanding ecotourism projects that result in forest preservation, Tropical Nature protects prime habitat in Peru, Ecuador, Bolivia, and Brazil—home of the rock-wielding capuchin monkeys.

Free World Map

Watch capuchin monkeys smash nuts—and a misplaced thumb—with rock tools.
RealPlayer  WinMedia

Videography by Charles Munn, Tropical Nature



Beck, Benjamin B. Animal Tool Behavior: The Use and Manufacture of Tools by Animals. Garland Publishing, 1980.
Rowe, Noel. The Pictorial Guide to the Living Primates. Pogonias Press, 1996.
Trivedi, Bijal. "Chimp Nut-Cracking Site Offers Clues to Early Tool Use," National Geographic Today. Available online at


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