Grooming Behavior Among Chimps

Like insect fishing and nut cracking, grooming behavior, which involves one chimpanzee picking insects, bits of dirt, and other matter out of another chimp's coat, varies from group to group. In the mid-1990's, Christophe Boesch, an anthropologist at the Max Planck Institute for Evolutionary Anthropology in Germany, reported that the chimps at Gombe had begun using leaves to squash the small parasites that they pulled from one another's coats. Boesch speculated that the chimps started doing this either because the leaves made it easier to kill the hard-shelled parasites or because the chimps did not like getting their hands messy. In either case, the behavior appeared among a few chimps and then spread throughout the entire troop.

In contrast to the Gombe chimps, Tai chimps remove the parasites, place them on a forearm, smack them with their hand, and then eat them. As with insect fishing, these two approaches to grooming among widely separated groups of chimpanzees are different solutions to the same problem, indicating that group members acquire the particular approach through social learning processes.