This book is a critique of the experiments of recent years that tried to teach language to apes. The achievements of these animals are compared with the natural development of language, both spoken and signed forms, in children. It is argued that ...
the apes in these studies acquired merely crude simulations of language rather than language itself and that there is no good evidence that apes can acquire a language. A survey of the communication systems of apes and monkeys in nature finds that these systems differ from language in profound ways--language is a uniquely human attribute.