The Teaching Gene
- The Evolution of Culture in Animals by John Tyler Bonner
Princeton, 216 pp, £8.10, May 1980, ISBN 0 691 08250 2
It is a pleasure to write about a book that is so well-written. John Tyler Bonner is a biologist who not only knows a great deal about plants and animals but has thought long and carefully about problems of evolution. He has a cool and judicious attitude that allows him to settle contentious questions without fuss. For example, in order to show that ‘there is no need to be tyrannised by words,’ he makes fun of anthropologists who object to the use of such words as ‘slaves’ or ‘castes’ in describing colonies of ants, because it may imply that if these practices are natural to them they are legitimate also for us. The biologist thinks that both the similarities and the differences are so obvious that it is convenient to use the words and ‘unnecessary to drag in all the possible political, psychological, or strictly human nuances’. This question of the use of words is important for Bonner because he proposes to use the word ‘culture’ to cover a great variety of living activities.
In searching for the origin of human culture he enters into several controversial fields. Biologists have recently been worrying again about basic evolutionary problems, including why certain species evolve while others stay the same. In some cases, evolution is so rapid that it can almost be followed in a human lifetime. In the last century, moths became dark in industrial areas but are now getting lighter again as pollution is controlled. Even their behaviour has been reversed, so that they settle on bark of the right colour. On the other hand, geologists searching rocks 25 million years old find ear stones of species of fishes and squids that are still alive today. So for some species evolution is very fast, but others stay the same for very long periods indeed. Can we find evidence as to what speeds up evolution? Could it be the use of the brain to process information?
The question of the speed of human evolution is especially important. Man is undoubtedly very different from even his closest living relatives. Did the changes that produced language, logic, conscience and culture perhaps occur in a few years and if so what caused them to happen? Studies of ancient climates have recently produced evidence of very rapid changes, which also coincide with periods of rapid extinction for many species – for example, during the Ice Ages. So evolutionary history may have included a series of catastrophes and one of these may have occurred close to the origin of man as he is today.
Professor Bonner does not confront these questions of rate of change directly. His concern is to ‘trace the origins of human cultural capacity back into early biological evolution’. He specifically states that he is not a catastrophist and does not believe that, ‘like the Great Flood, culture suddenly appeared out of the blue at a restricted moment in the early history of man’. His following of the track of ‘culture’ leads him right back almost to the origin of life. He finds its antecedents even among plants, bacteria and slime moulds, let alone ants, termites and bees. This may seem to be carrying things too far, but his point is that the capacity for transmission of information by culture depends upon the power to adapt during the lifetime of an individual. He thus distinguishes between ‘a quick flexible response for cultural evolution and a slow ponderous response for genetical evolution’. Even plants can adapt their form to suit the environment. He cites the example of the arrowhead, whose long lovely leaves that one sees waving in many of our streams are quite different from the arrow-shaped leaves of the plants on the bank nearby.
Such examples may seem to have little to do with the subject. The change in the leaves of the plant is not due to the passage of information by culture. But Bonner’s point is that before there can be culture there must be power to respond to that information. Both of these are present when the plant changes its form. Indeed, the capacity to make such adaptive changes in the space of one lifetime is probably universal in living things, though we know little about how these changes happen.
Culture as we usually understand it is, of course, a property of some more complex types of animal. Bonner defines it as ‘the transfer of information by behavioural means, most particularly by the process of teaching and learning’. He gives us a very wide survey of the creatures in which these powers are found, with ingenious explanations of why they are present in some species but not in others. The more elaborate forms of teaching require the use of a system of signs or language. Bonner does not spend much time on discussing how simpler forms of signing developed into human language. He explains how the social insects, especially bees, gain advantages from communication and altruism because their special method of reproduction makes them ‘an extended family’. The controversial question of the importance of ‘kin selection’ figures largely, but Bonner does not venture into the difficult problems of the origins of human altruism.
The pleasure of the book is in the wealth of examples of communication and teaching, many effectively illustrated with drawings or photographs. In each case where groups of individual animals share a ‘culture’ it gives them the power to adapt rapidly to the particular conditions imposed by the environment. Birds that live in thick forests keep together by singing duets, which each pair gradually learns and practises. The parrot’s and mynah bird’s proverbial powers of imitation probably have a similar explanation: these species form close links between mates, which are confirmed and maintained by the duets they sing. But these are examples of transmission of information only between two individuals. They come within Bonner’s definition of culture, but would hardly qualify in the more usual sense of the word. Bonner faces this challenge directly: ‘Many anthropologists and social scientists, of whom M. Sahlins is an eloquent representative, take the view that culture can have no direct genetic determination. It is a new form of social by-product that arose in our early history ... and the simple-minded view that there could be any genetic component is seriously misguided.’ Bonner’s reply is not very convincing. He seems up to this point to rest his case for a genetic component in culture on the fact that one is certainly present in ants and perhaps in the murder of rival males after the takeover of a pride of lions!
He obviously does not mean this to be the only evidence to support his view, which is that ‘the only intolerable position is that of either extreme: that all or no cultural phenomena have a direct genetic involvement.’ In fact, he does not cite much of the evidence – for example, that humans are pre-programmed both to produce and to receive speech. It is plausible to suppose that human habits of logical thought and reasoning are based upon inherited cerebral organisation, but the extent of this is uncertain. In any case, it is quite clear that many human capacities for communication have a hereditary basis, as Charles Darwin showed long ago – for instance, the smile of an infant and his yell of displeasure. Indeed, all powers of learning and teaching must depend upon particular activities of the brain. Each animal species is programmed to learn in its own special way and this must apply also to man. My own view is that humans as social creatures are genetically programmed to learn how to respond to each other.
Bonner begins his final summary of the evolution of culture by reasserting the belief that the grand sweep of evolution involves the opening of new niches, and he instances the colonisation of the land. But this unfortunately overlooks the problem of whether the fossil series show repeated replacement of each type of organism in the same niche. Although some species of fishes have survived for many millions of years, Dr Greenwood of the British Museum has shown that several new species have arisen in African lakes in the last few thousand years. Bonner’s point seems to be that use of the brain to allow transmission of information has enabled change to proceed more rapidly than by alteration of the inherited genome. The examples he gives are all interesting, but in the nature of the case it is difficult to prove the point. He gives good descriptions of several of the classic examples of animal learning by imitation. There is an excellent drawing from Jane Goodall’s photograph of a young chimpanzee learning to dig for ants. Young oystercatchers learn how to open mussels and of course British blue tits have learned to open milk bottles. Perhaps closer to his purpose is the striking picture of a day-care centre of penguins. Where the nesting ground is far from the sea both parent penguins go off to collect food while all the young are left together in one huge creche in the care of a few adults. Unfortunately we do not know how this system of behaviour has come about.
What do all these examples really tell us about the origin of human culture? Unfortunately not much. Bonner believes that the special feature is that ‘man has also greatly improved the art of true teaching’. But how did this come about? The only clue available is the scanty evidence about the increase in size of the brain during the last one and a half million years.
Bonner’s difficulty in discussing the origins of human culture is that he has ‘tried to adhere to biological problems and avoid discussing anthropological and social ones’. He has specifically avoided entering the controversy that has arisen over the tenets of sociobiology put forward by E. O. Wilson and others: ‘battle lines at the juncture between biology and the social sciences have been drawn ... it is important for the biologist to understand that flashes of insight, through the aegis of kin selection, will not solve all problems of the social sciences.’ Nevertheless, the social scientist ‘must face the possibility of some biological information being extraordinarily useful to him’. Let us hope that it will indeed be so. We certainly need all the clues we can find to the discontents that arise from the differences between human cultures. Why do we have this tendency to fall into groups, large and small, with different languages and cultures and often ferocious antagonisms? This is perhaps the most important of all the problems that face mankind. We should not allow ourselves to be so frightened by its actuality that we cease to discuss it rationally. Professor Bonner has given an example of how to proceed, in a book that is both lucid and charming.