A number of researchers have suggested that neoteny played an important role in the craniofacial evolution of the genus Homo and its close relatives (Abbie, 1947; Bolk, 1926; Brothwell, 1975; de Beer, 1958; Gould, 1977, 2000; Montagu, 1989; Privratsky, 1981; Verhulst, 1999). The same has also been suggested, at least in part, for the evolution of Pan paniscus (the “pygmy chimpanzee” or bonobo) (Rice, 1997; Shea, 1983, 1989, 2000, 2002; see also Coolidge, 1933). Comparisons of fossil as well as extant taxa have been brought to bear on the problem. Rozzi (2000) suggested that changes in molar morphology, from Australopithecus afarensis to the robust australopithecines, may be attributed to neoteny. Antón & Leigh (1998) held that neoteny helps to explain the evolution of craniofacial form from Homo erectus to Homo sapiens. Czarnetzki et al. (2001) invoked neoteny to explain the development of adult Neandertal traits. Finally, Alba et al. (2001) and Alba (2002) characterized the reduced canine size and facial prognathism in both bonobos and Oreopithecus as “paedomorphic,” and Shea (1984, 2000) characterized the “paedomorphic” facial skeletons of bonobos as “neotenic,” relative to a hypothetical Pan troglodytes-like ancestor.
The notion that modern humans and bonobos are neotenic has also come under severe criticism. Shea (1989) contested the neoteny hypothesis for human evolution (as did McKinney & McNamara, 1991 and McNamara, 2002) while upholding neoteny for bonobos. Godfrey & Sutherland (1995, 1996) challenged the evidence brought to bear on the arguments for and against neoteny in both humans and bonobos.