Bonobos, or pygmy chimpanzees, are similar to Chimpanzees in many ways.  Because of this similarity, I am only detailing some of the differences below.  Currently, Bonobo populations number less than 20,000 individuals.

     Bonobos live near and along the Zaire river in the lowland rainforests and swamp forests.  Bonobos can be distinguished from chimpanzees by their more slender frame, longer hind limbs, shorter clavicle, and smaller molars. Bonobos are generally smaller than chimpanzee and are also less dimorphic-- males only 30% heavier.

dimorphism \Di*mor"phism\, n. [Cf. F. dimorphisme.] 1. (Biol.) Difference of form between members of the same species, as when a plant has two kinds of flowers, both hermaphrodite (as in the partridge berry), or when there are two forms of one or both sexes of the same species of butterfly. dimorphism is the condition of the appearance of the same species under two dissimilar forms. --Darwin.

     Bonobos live in multi-male, bisexual communities, or "unit-groups," which range in size from 50-120 individuals. Subgroups of from 1-70 individuals are also seen, usually consisting of matrifocal subunits. The communities are closed social networks within which individuals forage partly independently. In a Bonobo society, it is seen that females play the dominant role.  Bonobos societies are different from those of many other primates in that transfer between groups is done by the females and not the males. Females leave natal groups as older juveniles or in early adolescence (7-9 yrs) and transfer to another unit-group, in which they breed and grow old. Older females maintain strong bonds with their grown adult sons and occupy the highest ranks among the females of the group. Males, on the other hand, stay in their natal group and acquire rank based on their mother's rank. Intercommunity relations are antagonistic.

     Bonobos have abundant, mutual precopulatory and copulatory signals, variable copulatory postures, and more prolonged copulations than most other primates. No birth seasonality is apparent. Females have midcycle sexual swellings of the perineal region to show sexual receptivity.  Bonobos have some kind of sex almost every day. Females are in heat for three-quarters of their cycle, and many of them copulate even when not in heat, a sexual pattern more like human females than that of any other mammal. Though common chimpanzees only have sex to reproduce, Bonobos share all kinds of sexual pleasures.