ABSTRACT
Before bonobos were well known, chimpanzees were assumed to provide a good model of the ancestral state. Then, following an early ‘scala naturae’ argument by Coolidge (1933), Zihlman and her colleagues proposed bonobos to be more similar to the common ancestor, on the basis that they were “the most generalized of the African apes and have many ‘primitive’ features, particularly the shorter humerus relative to femur” (Zihlman and Cramer, 1978:92; see also Zihlman, 1979; Zihlman et al., 1978). Although Zihlman’s idea provoked considerable research into the comparative morphology of African hominoids, it has been neither fully supported nor fully refuted. The consensus is much as Wood (1994b:31) concluded, “it is at present unclear with
which of the two extant species of Pan the modern H. sapiens should be compared.”
