Broca’s Brain 
by Carl Sagan.
Hodder, 347 pp., £6.95
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When I saw the title of Carl Sagan’s new book, I was troubled. I was afraid he might have followed the path of other scientists who turn to study the brain because they are disillusioned by the inhumanity of physical science. I need not have worried. He remains an enthusiastic astronomer. The title refers to the sprightly opening piece in which he describes a visit to the backstage storerooms of the Musée de l’Homme in Paris. There he happened to come upon the brain, in a bottle, of the famous Dr Broca, who in 1861 first showed evidence of an area in the human brain which controlled speech. The specimen prompted Sagan to speculate that Broca’s memories and insights might still be there in the brain in the bottle. This macabre but imaginative thought is typical of him, and it does indeed prompt reflection in the neuroscientist.

Knowledge is certainly somehow incorporated in the brain. The particular connections that are made there by experience may remain dormant for a lifetime, and then suddenly give rise to a memory of an event that occurred, say, 80 years earlier. The record must be printed in the tissue. Would it even be possible to recover it after death? This rather frightening thought at least reminds us how ignorant we are about memory. We do not know how to look for those connections that make up the memory, nor even whether they truly persist after the brain stops working. But recent advances make it likely that we shall know much more about this, and about many other matters, before many decades have passed.

A recurrent theme of Sagan’s book is that what we have learned from science in recent years is only a beginning, and that the discoveries ahead will be wonderful, beautiful, and useful to mankind. He faces the problems that knowledge brings and even the ‘lurking fear, made explicit in the Faust legend, that some things are not “meant” to be known, that some inquiries are too dangerous for human beings to make.’ But he notes that such fears are characteristic of human beings, that although they may have served an adaptive function in the past, they are now ‘mostly emotional baggage’.

This book of essays contains many examples of his careful and cheerful optimism. Although the pieces are independent, he explains that they have been carefully arranged. The idea seems to be to build up an image of the cautious and reliable scientist, so that the reader is ready to accept his ideas of extraterrestrial life, even though they are speculative. In the early stages, he shows convincingly that he is not simply a credulous believer in strange ideas and paradoxes at ‘the edge or border of Science’. He notes that some pseudoscience is a profitable enterprise and needs to be studied with this in mind: ‘extraordinary claims require extraordinary evidence.’ In this spirit he examines and mostly rejects the claims of astral projection, spirit rapping, mathematical horses, precognitive dreams and paranormal phenomena generally. He is not ready to credit the claims of spiritualists and fork-benders, noting that the latter are quite ‘happy to warp keys and cutlery in the vicinity of scientists … but are greatly affronted at the idea of performance before an audience of sceptical magicians … who understand human limitations and are able to perform similar effects by sleight of hand’. Sagan is not even ready to accept the evidence of UFOs, which must be attractive to him in view of his deep interest in the possibility of life on other planets. His understanding of human nature warns him to look for an explanation of people’s readiness to believe in reports of paranormal and strange cosmic phenomena in the attractions of novelty and ‘the feelings of insight and grandeur they provide’. But he certainly advocates hearing both sides of all such questions.

Many of the later essays deal with questions of space travel, on which he is an authority. With a sound historical sense, he notes that we live in the Golden Age of Planetary Exploration, but also that very much lies before us. He has no doubt that ‘we are set irrevocably, I believe, on a path that will take us to the stars.’ But that does not mean uncritical acceptance of expensive manned missions. He doubts whether spending $200 billion for space stations, or to put man on Mars, is ‘socially responsible’. But such schemes ‘may one day be implemented and there is much that is far reaching and historically significant in them.’ Does this refer to history of the past, or as is more likely, to that of the future?

He believes that we shall obtain great benefits from space and from the search for other intelligences. But the advantages are not spelled out in detail. They include ‘important technology, with applications to many other aspects of our own civilisation. We will have added greatly to our knowledge of the physical universe. And we will have calibrated something of the importance and uniqueness of our species.’

Sagan’s particular preference for immediate exploration is the carbonaceous asteroids that mostly occur between the orbits of Mars and Jupiter, and he would like a manned mission to be sent to one of these. Their organic matter is thought to have been formed in the earliest stages of the formation of the solar system. Study of it would be of great interest for its bearing on the question of the origin of life. Such a landing would be relatively cheap and, as he says, ‘great fun’ – ‘because the gravity field is so low, it would be possible for an astronaut to do a standing high jump of about ten kilometres.’

He is perhaps best known for his interest in attempting to communicate with other worlds. He admits that many questions are unanswered. For instance, if there are such wise intelligences, ‘why have they not restructured the entire Galaxy for their convenience?’ If they are so clever, why have they not come here? This prompts him to the thought that they may have come and gone, and that the fate of all such civilisations is to destroy themselves. But he believes that it is premature to despair of extraterrestrial communication. It may be that we are too stupid to read signs that are already here. Many aspects of the signals we are receiving from quasars and pulsars are not understood, and they may contain the very messages we are looking for from other intelligences.

The last section of the book deals with Ultimate Questions including the existence of God and the origin of the Universe. He gives good accounts of the Big Bang and Constant Creation Theories, but the connections he suggests with theology are rather feeble. He goes to the root of the matter when he says that ‘the way to find out about our place in the universe is by examining the universe and examining ourselves.’ It is a great strength for an astronomer to be ready to consider biological questions. All theories, after all, arise in the human brain and are subject to its limitations. But in his final essay, called ‘The Amniotic Universe’, he pursues this idea to the point of absurdity. He suggests that the various theories of the origin of the universe are conditioned by the experiences of birth, which some psychologists believe control all subsequent thinking. He suggests that we may be so conditioned that we are incapable of constructing a cosmology ‘that is not some mathematical encrypting of our own personal origins’. For example, the preference of some for a Steady State cosmology is a recollection of uterine content. Conversely, the reluctance of some astronomers to accept the idea of a Big Bang that lasts for ever reflects a memory of the trauma of birth, which should be terminated by the bliss of the breast. Some theologians actually prefer this theory because the pains of birth have convinced them that life is evil! And so on. Sagan thinks that the ‘possible connection between psychiatry and cosmology seems very real.’ Perhaps he has ventured here rather too far into neuroscience. But he is a great explorer.

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