Adrian Desmond (The Hot-Blooded Dinosaurs) is an engaging English paleontologist not afraid to go out, with others, on an evolutionary limb. Here his concern is how close--truly kindred--are ape and human behavior, given an astonishing 99 percent chromosomal overlap. Challenges to human uniqueness with respect to tool-use, tool-making, and linguistic capacity have been noteworthy in the past decade. At the same time, the observations of Goodall and others have confirmed incidents of infanticide, murder, and cannibalism among chimpanzees in the wild, suggesting that the darker side of man's behavior is also not unique. But this comes later. Much of the book deals with studies of language capacity in chimpanzees and gorillas--via the American Sign Language taught to Washoe and other chimpanzees by the Gardners and their students; the plastic-symbol-manipulating technique pioneered by David Premack with the chimpanzee Sarah; and the ingenious computer-language trainer developed by Georgia State University psychologist Duane Rumbaugh. Desmond makes it clear that there is as much disagreement among the chimp trainers as exists between them and the psycholinguists (Noam Chomsky, Roger Brown, et al.) who hold out for human uniqueness. (The definition of human language, Desmond remarks, tends to change with each demonstration of ape ingenuity.) Desmond comes out on the side of ape competence, especially savoring some of Premack's novel experiments exploring chimpanzee logic and inference. He fairly points out the dangers of cueing, rote learning, and conditioning, and takes some investigators to task for selective reporting--failing to note the gibberish or errors the apes make. What incenses him particularly is the assumption that apes attach human meanings to abstractions like ""please"" and ""sorry."" But here he can be faulted for inconsistency, for while he sharply limits human notions of ""sorry,"" elsewhere he imputes to apes complex, insightful plans, even including ""cheating""--which would make them the very mirror of man. What he wants to do is to establish (if not define) the ""sovereign"" chimpanzee, unique in its own right. One sympathizes with his desire to eradicate the 19th-century onward-and-upward notion of evolution, while at the same time one deplores his all-too-easy acceptance of Marvin Harris' cultural materialism. Clearly, not all the evidence is in; but in bringing us up to date, Desmond has provided a useful handbook with which to follow a lively debate.