_N_ATU__ ~__ v_o_t_ .. ~_~ __ 3t_MA __ R_t_·H __ t%_3 _____________________ E3()()~~E:\/If:\A/~-----------------------------------------45_7 between intelligence and the brain/weight ratio. Self-conscious asides He is equally scathing on the doctrine of encephalization of function, that is that in Stuart Sutherland vertebrate evolution the locus of behavioural functions moves progressively Animal Thought. By Stephen Walker. forward in the brain, particularly into the Routledge & Kegan Paul: 1983. Pp.437. £17.50, $35. forebrain, and neocortex. He points out that the hypothalamus is present in teleost FIFTEEN years ago, my interest in lated in consciousness) and that far from fishes and can be regarded in all vertebrates comparative psychology made it necessary inventing the association of ideas as a as the head-ganglion of the autonomic to keep a number of different animals. A general explanatory principle, he thought it system: its functions do not seem to have distinguished worker in artificial was a thoroughly bad thing and was the shifted. Moreover, although they only intelligence happened to visit me and explanation of the "madness, found in have a rudimentary cortex, birds display asked: "Haven't you got anything better to most men". Darwin was curiously soft on learning abilities in no way inferior to those do than keep a zoo?''. Although at the time animals, ascribing to dogs a sense of of many mammals. his remark seemed to lack a proper humour and a belief in the supernatural. As After an interesting but speculative appreciation of the scientific spirit, the to the behaviourists, they denied thought chapter on the survival value of subsequent history of comparative to both man and animals thus placing them intelligence, Walker concludes with a psychology suggests that he may have had on the same level. survey of perception and memory in more sense than I credited him with. Walker concludes that little reliance can animals and an account of monkeys' use of At that time comparative psychologists be placed on the authorities and that one knowledge and their ability to learn to use were painstakingly measuring the can only decide whether animals think like signs. He is somewhat preoccupied with the performance of different groups of man by examining how far their behaviour notion of conscious thought, and takes as animals on a large number of learning and neuroanatomy are similar to our own. evidence for it the finding that many tasks. They were trying to construct a two­ The idea that similarities in neuroanatomy animals can be trained to wait for a minute by-two table on which the axes represented are relevant to consciousness is not new. or more after having received a signal to tasks and groups, and the cell entries Walker quotes Charles Kingsley satirising respond, and can still make the correct represented performance. Apart from Thomas Huxley who is made to declare reaction. But this surely does not imply that keeping themselves busy, they had two that apes have "hippopotamus majors" in the animal has a conscious memory of the aims. First, by discovering sets of tasks in their brains just like men: signal. Again, recent work on animal which any species that could perform one learning proves that animals do not learn task could perform all the others, they You may think that there are more important merely to make responses on the basis of hoped to infer the nature of the skill needed differences between you and an ape, such as rewards and punishments - they learn for all the tasks in the set. Second, by being able to speak, and make machines, and what sequences of events occur, but this know right from wrong, and say your prayers, examining the neuroanatomical dif­ and other little matters of that kind; but that is a does not demonstrate that they have ferences between the species that could and child's fancy, my dear. Nothing is to be conscious expectancies, even though they could not perform a given task, they hoped depended on but the great hippopotamus test. act as though they do. Indeed one of the to learn about the brain mechanisms main problems with consciousness is that underlying successful performance. For Walker gives a clear account of nobody has been able to suggest any several reasons this laborious approach to comparative neuroanatomy, in which he evolutionary advantage for it. Men can the problem of comparative intelligence displays a pleasing cynicism about the learn and carry out highly skilled and proved a failure. It turned out that in many specious generalizations often drawn in complex motor patterns without being cases whether or not an animal could be that field. Much effort has been wasted conscious of how the movements are trained to perform a task reflected not its measuring brain size and wholly useless executed and it is not apparent why taking own native wit, but the ingenuity of the equations have been produced, such as the certain decisions or using language should experimenter in devising training appro­ formula governing the (approximate) ratio involve consciousness. priate to the animal's natural way of life. of brain weight to body weight, which for Walker is in fact concerned that Moreover, the assumption that the same mammals and birds is E= 0.07°·67 P (where consciousness may be bound up with anatomical part of the brain, as defined by E is the expected ratio and Pis the body language, in which case one would have to its evolutionary origin, has the same role in weight). Some intelligent species such as deny animals conscious thought. But we do all species is false. Removing the man, the crow and the porpoise have a not deny consciousness to infants and on hippocampus in a rat has very different brain weight considerably in excess of that her own account Helen Keller, who was effects on behaviour from those produced predicted by this formula, but measuring deaf, dumb and blind, was conscious by removing it in man. Finally, there is brain size is no more likely to tell us before she learned to communicate. often as wide a range of ability on a given anything significant about how the brain Regardless of language, the similarity task within a group as between groups. works than measuring the size of between human and animal behaviour and Although Stephen Walker sets out to computers is to reveal the programs they neuroanatomy surely justifies Walker in answer the question how far animal and can run. Moreover, the appearance of ascribing conscious thought to primates human thought are similar, he is body weight in the ratio is curious. Birds, and other higher animals, but neither he thoroughly aware of the difficulties that for obvious reasons, are very light, and so nor anyone else is ever likely to penetrate beset comparative psychology. He starts are sharks which have a cartilaginous the thoughts of a lamprey. with a historical review of the opinions of skeleton and therefore turn in a high Animal Thought is a well-written and earlier authorities, which is more brain/body-weight ratio, although they are stimulating book, containing occasional interesting in its asides than in its main regarded as a primitive order of fish. flashes of wit. But it is interesting more for theme. Thus, it is of little consequence that Neanderthal man probably had a higher its obiter dicta and for its way of dealing Descartes thought animals (and machines) ratio than modern man, though he may of with hallowed nonsense than for its main could never have knowledge or language, course have been more intelligent. As message which will surprise few readers. ~ I but it is of interest that Locke formulated Walker remarks, since nobody has the recently rediscovered concept of succeeded in assessing the intelligence of Stuart Sutherland is Director of the Centre for "working memory" (only a small number animals (or man come to that) objectively, Research on Perception and Cognition at the of ideas can be simultaneously manipu- there is no good evidence for an association University of Sussex. © 1983 Nature Publishing Group.