Common chimpanzees (Pan troglodytes) are widespread in the forested parts of West, Central, and East Africa. Pygmy chimpanzees, or bonobos (P. paniscus), are restricted to the swampy lowland forests of the Zaire basin. Despite their names, common chimpanzees are no longer common, and pygmy chimpanzees are no smaller than the other species.

Chimpanzees are partly arboreal and partly ground-dwelling. They feed in fruit trees by day, nest in other trees at night, and can move rapidly through treetops. On the ground chimpanzees usually walk on all fours (knuckle walking), since their arms are longer than their legs. Their hands have fully opposable thumbs and, although lacking a precision grip, can manipulate objects dexterously. Chimpanzees make and use a variety of tools: they shape and strip "fishing sticks" from twigs to poke into termite mounds, and they chew the ends of shoots to fashion fly whisks. They also throw...