premise: Bonobos were separated from the ancestors of the common chimpanzee.
hypothesis: The bonobo ( [ bə.ˈnoʊ.boʊ ] or [ ˈbɒ.nə.boʊ ] Pan paniscus ) , formerly called the pygmy chimpanzee and less often , the dwarf or gracile chimpanzee , is an endangered great ape and one of the two species making up the genus Pan ; the other is Pan troglodytes , or the common chimpanzee . Although the name `` chimpanzee '' is sometimes used to refer to both species together , it is usually understood as referring to the common chimpanzee , whereas Pan paniscus is usually referred to as the bonobo . Along with the common chimpanzee , the bonobo is the closest extant relative to humans . Bonobos live south of the river , and thereby were separated from the ancestors of the common chimpanzee , which live north of the river . Chimpanzees ( sometimes called chimps ) are the species of the great apes in the genus Pan , consisting of the common chimpanzee and the bonobo .