Chimpanzee Tool Use and Social Behavior

Although other scientists had previously observed chimpanzees in captivity using tools, Goodall was the first scientist to witness chimps in the wild engaged in that activity. On an October day in 1960, soon after she arrived in the area that is now Gombe Stream National Park, Goodall noticed a rustling in the tall grass on a slope. She crouched to the ground, pulled out her binoculars, and watched as a chimpanzee dipped a grass stem into a termite nest to get at the burrowing insects. Over the next several years, Goodall made many observations of termite and ant fishing and discovered that the entire troop of chimpanzees at Gombe engaged in these behaviors.

Beginning in the 1970's, other teams of scientists began studies of chimpanzee behavior in different regions of Africa. In 1999, seven research teams, under the guidance of Whiten, pooled their data and published their findings in the British journal Nature. The investigators reported 39 different chimp activities that met their definition of culture as behavior that spreads throughout a social group through imitation. The most significant of these behaviors were the use of simple tools and activities related to grooming and courtship. Most importantly, the different groups of chimpanzees took individualized approaches to similar tasks. These variations could not be explained by either genetic or environmental differences, and so they must have spread through imitation and—possibly—intentional teaching.

For example, the scientists described the varying insect-fishing methods used by different chimp groups. They noted that the chimps at Gombe usually use a long stick or stem to extract termites and ants from their nests, and they tend to remove the insects from the probe by swiping their hands along it. Chimps at Tai and at a site called Bossou, in Guinea, are more likely to fish with a short stick and to strip the insects from it with their mouth. Another example of cultural variation in chimpanzees is the use of tools to crack open nuts. At Gombe, though there are plenty of nuts, the chimps haven't learned to open them, despite an abundance of rocks that would be ideal for the task. In contrast, chimps at Bossou use stone “hammers” to crack open nuts on either stone or wood “anvils.” Chimpanzees at Tai also open nuts in this manner, and they often use pieces of wood as well as rocks for their hammers.

According to the scientists, nut cracking by the Tai chimps provides a good example of a behavior that is learned by young chimps through imitation and then practiced by them as adults. While adult Tai chimps expertly open nuts with their hammers and anvils, the young chimps try pounding on nuts with rotten branches, pieces of fruit, and even chunks of termite mounds. They eventually discover that the stones and hard pieces of wood used by the adults work the best.