"The only book on our origins that will be read 100 years on". Surely not? But this book hides the nuts and bolts of a new answer to an old question that will reshape the sciences of human nature - below I give details and let you decide whether this is indeed the next big thing.
But first that old question: what turned the human brain -- initially evolved 100,000 years ago to be, and only be, a smart hunter-gatherer -- into a brain that in each of us is superfitted for our hi-tech modern life. The problem is an embarrassment to science. No neurologist or paleoanthropologist can explain why your brain so obviously not evolved to read this, does so, like with so many other nonevolved modern skills, with such great finesse. Human evolution lacks foresight and so could have made no preparation. It is a big question. Evolutionary psychology offers no explanation. But the genius of Skoyles and Sagan provides a clear and plausible account.
Before summarizing what that is, a criticism. You start off thinking this is Dragons of Eden: The 25 year Sequel -- but Carl was a science populariser; this book, though averagely well written, lacks illustrations and has rather too many notes and references - more a book for getting out of the library than buying for a holiday read. That said, you soon realize that, with all respect to Carl Sagan, this book is much more important than anything he wrote.
Request, even buy, and get it, for its explanation of that old problem. Chapter 14 lays out its core story one which fits together the jig-saw puzzle pieces that the authors have earlier assembled in chapters 3-13 that describe the latest findings in neuroscience and paleoanthropology. The synthesis they offer is a radically novel, reductive and unexpectedly powerful new neurobiological and anthropological theory of symbolism.
Two theories intertwine. First, that the radical changes in cognition and behavior that make us unique are piggybacked upon earlier evolved primate cognitions and emotions. Symbols - stand-ins - they show are at the heart of the human revolution. Evolved primate cognitions process innate inputs - but culturally transmitted nonevolved signs can co-opt their innate processes. The co-optation just needs (and humans are good at this) the ability to learn abstract associations. When symbols co-opt innate ape psychology, it is like an engine being put into a new chassis -- ape psychology is refitted thus into doing something radically new -- human psychology with all its nonevolved cognitions. For example, the core process of fear in apes uses the innate inputs of snakes, spiders, angry faces and blood. But humans can uniquely hock on novel sign inputs such as swastikas, the radiation sign, evil eyes and the thoughts of God - and so use them to power the radically new behaviors that make us cultural.
But what enables humans to put a new culturally derived `chassis' on the ape brain? Here is their second theory. Symbolic co-optation arose from the prefrontal cortex working memory acting as an abstract association "catalyst" upon neural plastic networks. Many molecules would meet too rarely to react unless another molecule - a catalyst puts them together. The same with the neural connections that underlie the abstract associations of symbolic cognition - the `catalyst' in this case being the working memory of the prefrontal cortex that can 'tutor' new neural links. And the new associations that it creates happen thanks to the recently discovered phenomena of neural plasticity which allows old cognitions to rewire to do radically new tasks. The theory uses bits of already established science. It is theoretical innovation at its best - clear "mechanical" sound processes with no hand waved `dues ex machine' processes. Simple - yet overlooked - perhaps because of the breadth of knowledge they bring together -- by those whose business it is to invent such ideas.
You have to read the argument to appreciate its explanatory power. For a hint, consider how our social attachment is both different and not different from that of other apes. Both ape and human attachment depends upon the same limbic processes. But in nonhuman apes, the inputs to such process arise entirely from the actual physical presence of another individual -hugging, grooming, facial reactions, and the feel of warmth. Symbolic culture puts new a chassis on these limbic processes by adding new inputs such as wedding rings, name changes, and rituals. In doing so, the new `symbolic chassis' enables our ape limbic brain to create human specific forms of social bonds - such as those of marriage, with distant kin, the supernatural and society. This idea is simply an act of genius since reveals how neuroscience and grammatology so easily fit under anthropology and even such fields as cultural studies.
Further, the authors make the breakthrough of showing how what is a transient and private emotion in other apes could by a simple scientifically analyzable process become one that in humans is resistant to separation (symbols can stand-in for missing people and relationships with them), and embedded in communities (symbols allow societies to define relationships and so build up social complexity). One hates the phrase "scientific revolution" or "new paradigm" but these authors have done it - the core problem of our origins has been found. They call their idea, the missing link of human evolution. And they are right.
The resulting approach is not only elegant, simple and powerful - but the stuff of which I bet further science discoveries will be born. It is the first book that can be properly called `neuropaleoanthropology'. It is the beginning of something big. The oddly titled book - a wrong title if there ever was one -- does what evolutionary psychology should have done, but has not - reveal the biological dragons under our anthropological Eden.