GENESIS OF INTELLIGENCE

Press, 24 June 1978, Page 17

GENESIS OF INTELLIGENCE

The Dragons of Eden: Speculations on the Evolution of Human Intelligence. By Carl Sagan. Hodder and Stoughton. 264 pp. $25.25.

(Reviewed by R. A. M. Gregson) The author, besides being Professor of Astronomy and Space Science at Cornell University, has a distinguished record as a writer on scientific topics that cut across conventional compartments. It was appropriate that he was honoured by being invited to give the first Jacob Bronowski memorial lecture at the University of Toronto in 1975, from which this book grew.

By training, Sagan is a biologist, specialising in the early evolution of life. He has extended his speculation into the intricate and difficult problems about the origins of human intelligence. His professional motivation is partly that in our search for intelligent life in outer space we may be guided in where sensibly to look by what we know of the evolution of intelligence on earth. Those of us who are forced to wait on airports know well that besides softcore erotica the publishing world is currently showering us with pseudoscience and antiscience about visitors from outer space. There is a resurgence of uncritical interest in what Sagan calls “often demonstrably erroneous doctrines that, if true, would betoken at least a more interesting universe, but that, if false, imply an intellectual carelessness . . . not very promising for survival.” Crackpottery, such as the musical preferences of geraniums, psychic surgery, the Bermuda Triangle, or the doctrine of special creation of mankind in spite of our deep relatedness in biochemistry and brain physiology with other animals, are examples of popular mythology. The problem is that the truth is complicated and scattered around with ifs and burs, whereas fiction based on a bizarre mixture of truncated facts

and conjecture is eminently readable because it feels simpler to the reader. We need speculation in science, to stimulate creation and discovery, but we have little need of oversimplication. When human knowledge about man himself has advanced to an order of complexity that bursts the bounds of any paperback, can we still get the problems over to the general reader? Sagan offers one of the best attempts yet. The origins of human intelligence go vastly further back than man, and the detailed structures we carry inside our heads bear features which started with the dinosaurs. The increase in information-carrying capacity of the human brain, beating by a factor of 100 our nearest mammalian rivals, and by over 1000 as compared with the brighter reptiles, is the current end-point of the progress from bacteria. But in man we have the breakthrough to storing information outside ourselves in far greater quantity than we could ever store within. Man is at the extreme in brain mass per body mass, and he has gone on from there. Given these differences in capcity, what can man do that his competitors cannot? Higher primates use language and reason after a fashion; there is not the sharp cut-off between man and the rest which some make an article of faith. Sagan speculates that the gaps which occur between the highest lizards and mammals, and between the highest primates and man, could have arisen precisely because some species selectively exterminated their brightest rivals.

His most novel thesis is that man, in the functioning of the older parts of his brain, has links with behaviour that our prehuman ancestors would have found of survival value. The dragons of Eden come in at this point, preprogrammed into our dreams and nightmares. Sagan also makes much of

the lopsidedness of brain function; his acceptance of the link between quantitative serial thinking in the left hemisphere and parallel artistic creation in the right is a bit too ready, but for the reader who is new to the topic his survey should have decided impact. There is a conflict between the modes of functioning of the older and newer brain; man has not yet matched the use of the brain to the technological world. Sagan traces the consequences of this in resistance to innovation, and in' the selfcontradictory positions, we take over issues such as drugs, education and abortion. The pressures to conform in modern societies decrease the possibility of producing gifted multidisciplinary thinkers; what Sagan calls the reptilian rationalisation of the educational process operates against the use of our most able people. The distinct human quality which leads us to value our lives must be intelligence in a high degree, for there is nothing else which is distinctly and uniquely human. Sagan advances the argument that as the brain activity which supports human cognition does not appear before the end of the first trimester of pregnancy, biology provides us with an acceptable answer to the abortion controversy, which interestingly is that adopted in a number of European countries. Various animals, including dolphins, are more mentally complex and more able to feel and suffer than is the human embryo in its early development. A consistent moral position would include firm strictures against the slaughter of whales, dolphins, apes and sea otters. To behave otherwise is to indulge an appalling human chauvinsim.

The problems of human morality are intertwined with our technological competence and insights; Sagan carries on Bronowski’s message, and provides a needed alternative to close encounters of the empty kind.