THE DRAGONS OF EDEN: Speculations on the Evolution of Human Intelligence

Carl Sagan, Our Man in Exobiology (life Out There), here expresses his thoughts about life Here, specifically Intelligent life. Engaging and gifted as an astronomer, Sagan admits to amateur status in the neurosciences. We must concur. He enthusiastically adopts Paul MacLean's concept of the triune mind--an old reptilian layer (site of aggression, ritual behavior, territoriality) overlaid with limbic lobe (site of passions), and topped by neocortex, the rational mind. It is true that there are old and newer parts of the brain but this model, with its suggested specificities and internal wranglings, is by no means accepted canon, even as loose metaphor. Sagan rides it for all it's worth, however, seeing dreams as an aspect of our reptilian (or ""Dragon"") mode, making comparisons with the Freudian triad (ego, id, superego), and wondering about racial memories, rites, and rituals as residua of these older brains within us. He frequently refers to anecdotes or the myths of Genesis to illustrate his ideas. The result is a book which is mostly speculative and could mislead an innocent reader who knows Sagan's excellent credentials as an astronomer and a prime mover in the Mars lander projects. The last part, dealing with computer intelligence, games one can play with computers, and other interesting tidbits about information storage (truly in ""bits""), is sound and interesting. For the rest, caveat emptor.