Despite Googling quite a bit, "John McCrone" seems to have very few traces; he appears to be a journalist of some sort, yet was noted in one place as being something of a "crank". This, coupled with his odd endnotes (they flow along generally with the text, by page number, giving a sense of where he picked up bits of info, but not actually referencing much) and the fact that way too many of them indicate "mostly my own speculation" (which is dandy if you're an "expert" in a particular field, but I could pull the same quality of speculations out of "my hat" which doesn't mean they're worth building a book on), made me wonder while reading this just how worthwhile this was.
This is not to say that what McCrone has postulated in The Ape That Spoke isn't plausible, it's just not terribly well supported. He does go back to some very basic forms of life, sea slugs, for example, to show how "learning" can happen in even reasonably uncomplicated neural system, and projects this into the various predecessors of man, and his model of "nets" has a ring to truth to it, it's just that the feel of the book is like that of "armchair cosmologists" who posit theories divorced from the rigors of mathematics or the applicable physics.
The book, generally speaking, moves from early hominids, noting comparative brain size to other apes, and through the various developmental stages leading up to humanity. There were a few physiological bits in here that I'd not heard of before (such as the voice box not "dropping" in the throat in children until about age 1, allowing them to swallow and breathe at the same time for nursing, or how the human oral cavity is particularly arched, compared to our close relatives, allowing for more complicated speech, etc.), which would have been more persuasive had the referencing been more traditional. One of the fascinating concepts is that "inner speech" provided a "time delay" mechanism that allowed the developing human mind to become self-reflective, constantly watching (and labeling) what had just happened in the flow of processed experiences.
Interestingly, McCrone seems to hold that consciousness is solely a "process" of the biological equipment, and the times of mental quietude (the "Now" of Tolle or samadhi experience of Zen and other disciplines) is simply returning to an animal-like blankness and that there is nothing there but the constant mental chatter.
As fatalistic as that sounds (and, admittedly, it echoes some concepts of the fascinating Zen Physics book I've referenced previously), McCrone does suggest that the human brain is malleable enough (he gives examples of how various areas of the brain have developed very recently to process speech, etc.) to be adapting to new technological realities, giving examples that were quite prophetic in 1991 (which was, after all, the year that the Web was first launched, and the cutting edge chip was the 486!)."... our sense of being conscious is an active process rather than some phantom object. Consciousness is the label for what we experience when the brain repeatedly matches incoming nets and memory to put together a string of understanding. As soon as the brain stops working - or even drops below a certain threshold of activity - consciousness evaporates. Consciousness is not something inside our heads that does all our experiencing of life for us. It is simply the description of the stream of recognition flashes that take place as long as our brains are at work ..."
Again, there is a lot to think about in this book, but, due to the caveats noted, there was the feeling hanging over it that one might just be following the blitherings of some guy a couple of stools down the bar, rather than a sober discussion of the possibilities suggested by current knowledge. However, if this sparks your interest, it does appear to be out of print but you can get a "very good" used copy of the hardcover (I have a paperback version which I suspect was a bookclub imprint of the fist US edition) for a penny (an even $4 with shipping), so there's no major reason not to pick up a copy if it sounds like something you'd like to check out.