Championing the ascent of reptiles as much as the descent of man, this thoughtful volume on the evolution of intelligence by Skoyles and Sagan is a welcome addition to the nature/nurture neurophilosophy shelf. The authors take us well beyond the 'usual suspects' listing of gross anatomical brain structure and function of the familiar phyla, traveling a welcome breadth of comparative data to include a wide variety of species (including our earlier selves). Rather than merely outline the familiar shopping list(s) of evolving structures culminating in the development of the modern human cerebral cortex, Skoyles & Sagan do not end with the discussion of its distinctive "associative" or "silent" areas of the brain of old (as so many other authors are still content to do). Instead, and throughout the book's eighteen chapters, we are treated to a series of detailed proposals concerned with the continuously adaptive neural architecture of both the intra- and inter-cerebral structures underlying the evolution human intelligent behavior.
Reminiscent of learning the names of Tolstoy's characters in the early pages of 'War & Peace', one meets here parts of the brain rarely mentioned (let alone claimed to be of any significance in explaining who we are and why we behave as we do). Following the publication of this volume, the long overdue and normally restricted cast of human brain features will now include the structure and functional connectivities of the anterior cingulate, the amygdala, the insula, the orbital and dorsolateral prefrontal cortex of the brain (and these are just a few of the characters amongst many others that might have been introduced here). We may still not be able to agree upon how best to measure intelligence (IQ, in my view, still tautologically measuring 'what IQ tests measure'), but the physiological substrates of the brain supporting intelligent behavior are slowly coming to be located and characterized. Many of the examples and theoretical components put forward may perhaps appear predictable to those familiar with modern paradigms in comparative psychology and the study of intelligent systems (both biological and man-made), but the real strength of this book is to be seen in its successfully discussing adaptive neural systems for the technical non-specialist. The story as told here is a great achievement for a book aimed at the popular science reader.
The basic thesis of the book follows the development of the nervous system in the aftermath of the 'KT event' (coincident with the demise of the reptilian dinosaurs), which favored flexible, mobile species with nocturnal, cold-adaptable behaviors, capable of finding shelter and forage. In contrast, species with relatively reflexive nervous systems, whilst satisfactory when situated in a stable, predictable environment, can often fail to adapt to changes within the time course of sudden catastrophic events. En route to the architecture of the modern human brain, we meet the aetiology of social and emotional life and their associated neural substrata in the prefrontal cerebral and limbic cortex (amongst other structures). The level of neuroanatomical detail is sufficient to provide a coherent and consistent story of successive adaptations leading to the development of 'higher intelligence', but the pathway taken argues not for this result deriving solely from phylogenetic mutation (per se), but, and more importantly, from ontogenetic neural plasticity and enculturation despite the SAME genetic makeup.
If this idea is new, and at first glance appears to be an uncomfortable one, don't panic! If the authors are right, your prefrontal brain cortex will soon get to work in generating some reflex inhibition, allowing one to assess (and reassess) the situation, temporarily delay one's actions, and then to organize and activate novel planned behaviors towards worked goals. Whether the modern human can prove him/herself to be intelligent enough to plan the survival of any future catastrophe (whether it be of our own making or another KT-like event) we will have to wait and see. In the meantime we have in this book, an accessible version of a still-emerging story telling how, and as the solution to what challenges, the intelligence of a variety of species (including modern humans) currently evolved to demonstrate.
Excellently referenced throughout, with bibliography aplenty for those wishing to read more of the detailed research literature, my only gripe with this book would be with its lack of visualization aids for those unfamiliar with the brain areas mentioned. Although the text is sufficiently detailed to allow the reader to construct crude schematics for him/herself (as one may have done in the case of Tolstoy's family trees?), both anatomical and flowchart illustrations might be of help in hastening the orientation of those perhaps new to the anatomy and neurophysiology of the brain.
Whether this would indeed have been the book that Carl Sagan would have written in 1977 had he possessed the vast corpus of knowledge concerning the brain now available, one may only guess? It is my own view that Skoyles & Sagan's title serves more than to merely pay homage to 'The Dragons of Eden', in whose memory this book is in part written.