Smithsonian National Zoological Park l Friends of the National Zoo



The Think Tank exhibit takes a special look at tool use in chimpanzees. Chimpanzee tool-using ability was first studied almost a century ago, and since then much data have been collected on chimpanzee tool use and problem-solving abilities.

The exhibit shows how chimps use external objects to attain goals such as: stems to "fish" for termites, rocks to open nuts, and grass roots chewed up and then used as sponges. Visitors are also given the chance to "fish" for termites using a variety of grasses, branches, and twigs.

Chimpanzee tool use allows clear inferences of image, intention, and flexibility, showing that it is based on thinking. For example, when a chimpanzee fishes for termites with a grass blade or opens nuts with a rock, we can infer that the chimpanzee has an image of the hidden resource and the right grass blade or rock for the job. Intention is shown in that chimps select and even modify termite fishing tools before they reach a mound. Also, they will use the same rocks for opening nuts over and over again, even carrying the rocks to a supply of nuts. Chimps show flexibility when they modify their fishing tools to be more effective. When Plan A doesn't work, chimps are able to go to Plan B.

Chimpanzees learn to use tools by imitating and practicing what they see. Sometimes mothers will actually correct their young as they learn how to use a tool. There are also different techniques and regional differences in how chimpanzees use tools to accomplish a task. Some chimps fish for termites with delicate grass stems or twigs; others use strong, rigid sticks to break into a termite mound. One behavior, called "pestle-pounding", has been observed in only one small population of chimpanzees. Adults carry large logs to the tops of palm trees, bend the branches apart with their feet, stand up straight, and pound their pestle-log down into the bark. The chimps can then scoop out and drink the juicy pulp.