bonobo, smaller of two species of chimpanzee, genus Pan. Whereas the common chimpanzee, P. troglodytes, lives in forests across most of equatorial Africa, the bonobo, P. paniscus (sometimes called the pygmy chimpanzee), is found only in the Congo (Kinshasa) S of the Congo River. The bonobo has a more slender body build than the common chimpanzee, but there is considerable overlap in overall size (head-and-body length and weight) among individuals of the two species.

Bonobos share many behavioral traits with common chimpanzees; e.g., they tend to associate in groups, are day-active, build sleeping nests in trees, and eat mostly fruit and other vegetable matter. Their groups are usually larger than those of common chimpanzees, however, and often the females are closely bonded and tend to dominate males. Moreover, both males and females use sexual contact as a means of communication and a way to ease tensions that might otherwise erupt into conflict. Bonobos are less aggressive than common chimpanzees, and there are fewer conflicts between neighboring bonobo communities. Both bonobos and common chimpanzees have been able to learn the meanings of many human words (although they cannot vocalize them), and they can be trained to communicate with humans by using sign language or symbol boards.

The bonobo is listed as an endangered species. The few thousand that remain in the wild are hunted by humans, and their habitat is being fragmented by encroaching human settlement, agriculture, and logging operations. Bonobos are classified in the phylum Chordata, subphylum Vertebrata, class Mammalia, order Primates, family Pongidae.

Species (Pan paniscus) of great ape. It was once considered a subspecies of the chimpanzee, which it closely resembles in size, appearance, and way of life. Its range, the lowland rainforests of central Congo (Kinshasa), is more restricted than that of the chimpanzee, and it has longer, more slender arms, a more slender body, and a less protruding face. Bonobos eat mainly fruits but also leaves, seeds, grass, and small animals. They form communities of 50–120 individuals. A striking feature of their social lives is that they engage in sexual activity with great frequency, often as a means of settling quarrels, and with little regard for gender or age. Populations are shrinking, largely because of hunting and habitat destruction, and bonobos are an endangered species.

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