In 1979, Terrace, Petitto, Sanders, and Bever asked “Can an Ape Create a Sentence?” Looking at the evidence from a syntactic, semantic, and conversational point of view, their answer was no. Their conclusion was based on evidence from their own research with a common chimp, Nim Chimpsky, as well as on their analysis of data from other studies of ape language (Gardner & Gardner, 1973; Nova, 1976; Premack, 1976; Rumbaugh, 1977). Our goal in this chapter is to demonstrate that with a different species, the bonobo or pygmy chimpanzee, under a different set of conditions, the answer can be yes.

The study of ape language is important in establishing the evolutionary roots of human language. This is a subject on which there has been tremendous controversy (Bronowski & Bellugi, 1970; Limber, 1977; Petitto & Seidenberg, 1979; Seidenberg & Petitto, 1979; Terrace et al., 1979; Terrace, Petitto, Sanders, & Bever, 1980; Terrace, 1983). Is human language unique? Is it in any sense discontinuous from all that has preceded it in evolution? (See Vauclair, P&G11.) Or can we find the evolutionary roots of human language in the linguistic capacities of the great apes?

The human being is a unique species, but so is each species. In addition to being unique, we have an evolutionary history. Our physical characteristics and our behavior have evolved over long periods of time.

Evolution is conservative: It modifies the material that already exists and builds on it.