Donald's three-stage model of primate evolution begins with a plausible description of primate cognition at the level of chimps. He then proposes the crucial intermediary stage between chimp communication and human language, which he calls mimetic.

As far as I know--I'm not an anthropologist, I'm a cognitive systems theorist--this is an original contribution and is absolutely brilliant because is essentially solves the problem, in broad terms, of how we got from the cognitive processes employed by chimps when they communicate to the human cognitive processes we employ when we acquire and use language.

I have not actually finished the book. He begins with a valuable overview of various aspects of the problem of explaining language and understanding chimp capacity, reviewing theories, anatomy, anthropology, and both psychology and newer work under the heading of neuropsychology. He is a bit weak on the semiotics as far as I'm concerned, but he's working with a confused literature that is also weak. He then proceeds to his three-stage model. I got as far as stage 2, and started branching out from there and have never gotten back to it.

As far as I'm concerned this is the operative model of human evolution as it concerns cognition. ( )