The bonobo is a great ape endemic to lowland forests south of the Congo River in the Democratic Republic of Congo. Slightly smaller and more gracile than chimpanzees, males weigh ~39 kg and females ~31 kg. They have dark faces from birth (unlike chimpanzees), pink lips, a central hair parting, and longer limbs relative to body size. Bonobos are notable for their relatively peaceful, matriarchal society in which females form strong coalitions and social tensions are frequently resolved through affiliative sexual behaviors between all age-sex combinations. They are primarily frugivorous, supplementing with leaves, pith, invertebrates, and occasionally small mammals. They are highly arboreal but travel between food patches on the ground via knuckle-walking. Vocal communication is high-pitched. Females have a gestation of ~240 days and produce one offspring every 4–5 years. They can live over 40 years. Bonobos are considered a model for studying the evolution of cooperation and conflict resolution. They are Endangered due to bushmeat hunting, habitat loss, and civil conflict in their limited range.