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Apes, Language and the Human Mind. Sue SavageRumbaugh, Stewart G. Shanker, and Talbot J. Taylor. New York: Oxford University Press, 1998. 244 pp.
The proportion of the genome that humans and chimpanzees have in common is so great as to be both fascinating and puzzling. Anyone familiar with the behavior of wild chimpanzees cannot fail to be struck, not only by what we have in common, but also by how much we differ. Either we need to be more circumspect in extrapolating from genomic comparisons to the actualities of behavioral development, or we must be more tenacious in insisting on the ubiquity of environmental influences, not just on behavior, but on all aspects of ontogeny. The absence of even the rudiments of language in the natural behavior of chimpanzees invites the speculation that the experience of growing up in a human family might bring to light entirely new patterns of chimpanzee behavior, more human-like than anything seen in the wild. Perhaps they would even develop language? This prospect has inspired several investigators over the past fifty years to undertake the arduous task of raising an ape, either in the home or in an institutional setting, providing at least some home comforts and, above all, ample opportunities to learn language.
Such an undertaking is fraught with innumerable difficulties, both practical and theoretical. Although chimpanzees, like dogs, parrots, and other animals, readily discriminate between speech sounds, and can learn to respond differentially to them, of those listed only parrots imitate speech. Unlike chimpanzees, parrots possess the specialized brain circuitry needed for vocal imitation as a part of natural behavior. The inability of apes to acquire speech is sometimes attributed to an inappropriate vocal tract. Although characteristics of the chimpanzee pharynx probably do limit potential vowel space, this limitation could not itself completely eliminate the ability to imitate speech, any more than a cleft palate or glossectomy could completely eliminate speech in humans (Fletcher 1978). After months of intensive conditioning, one chimpanzee, Viki (Hayes 1951; Hayes and Hayes 1951), began producing novel sounds, eventually shaped by lip manipulation into an acceptable "mama." In the ensuing year or so she added "papa," "cup," and "up" (for a piggy-back ride). After more training Viki began using these words appropriately, although...