Corballis presents a plausible evolutionary mechanism to explain the tight linkage between cerebral lateralization for language and for handedness in humans. This argument may be bolstered by invoking Stokoe's notion of semantic phonology to explain the role of Broca's area in grammatical functions.

This paper points to the need in ape language research to shift from experimentation to ethnography. We cannot determine what goes on inside the head of an ape when it communicates with a human being, but we can learn about the nature and content of the communication that occurs in such face-to-face interaction. This information is fundamental for establishing a baseline for the abilities of an ape-human common ancestor.