Ape-language specialist Savage-Rumbaugh and science writer Lewin (co-author of Origins with Richard Leakey, 1977) run the superchimp Kanzi past us once again with this latest in the current deluge of books on animal brain power. Kanzi -- already a phenom with Newsweek, Time, and National Geographic covers to his credit -- is an ape with a mind of his own; his facility with communication (via a special keyboard) is a marvel. But Kanzi gets only limited airtime here; he's more like a sideshow barker's prop to entice the customers. The authors spend most of the book going over the history of ape-language research (and it does go back: Samuel Pepys's name is mentioned), briefly rummage in linguistic theory (long enough to unconvincingly trash Noam Chomsky), and visit with other ape subjects. When it comes to the use of language by the great apes, the jury is still out; they might have even gone home. Theorists continue to debate the importance of production versus comprehension, to dispute intentionality, to worry about an ape's reflectiveness. It is to Savage-Rumbaugh's credit that she gives as much importance to glances, gestures, and postures as communicative modes as she does to utterances and keyboard talent. It seems quite clear that the apes have no interest in joining the Yale debating squad, so why put them to that measure? When Kanzi is brought into the story, the tone lightens. He is a clever, humorous, astonishing character, and his developing relationship with Savage-Rumbaugh is where Lewin really shines. The quickly sketched vignettes are uniformly winning: For instance, Savage-Rumbaugh has her keys snatched by an obstreperous member of the ape troupe. She asks Kanzi to get them back. He shuffles over to the offending ape, murmurs in his ear, and the keys are returned forthwith. Call this effort ""Notes Toward an Understanding,"" for every theory is conjecture, but there are also many fine nuggets to be mined.