Instinct, Environment and Behaviour

Stephen Lea

• Publisher: Psychology Press
• Year: 2015
• Print ISBN: 9781138850439
• eBook ISBN: 9781317531685
• Topic: Psicología
• Subtopic: Historia y teoría en psicología

What can the evolution of animal behaviour tell us about human behaviour? More specifically, how good an account of animal behaviour can we give in terms of evolution, and how do humans fit in with or deviate from the pattern established for other animals?

The biological approach to the study of animal behaviour has important implications for psychology, but it is distinctly different. Originally published in 1984, this book provides a basic introduction to biological theories about behaviour, from the classic ethological tradition of Lorenz and Tinbergen to the later sociobiological approach. The principles of experimentation and research involved are assessed critically, especially with regard to their implications for the study of human behaviour. Written specifically for those with little biological knowledge, this book will still be of interest to students of biology and introductory psychology alike.

1
A biological approach to behaviour

When you are reading a play, do you skip over the list of characters at the beginning, and the instructions for setting the scene? If so, you probably shouldn't read this chapter. It tries to explain what the rest of the book is about.

My aim in this book is to introduce the biological approach to behaviour, usually called 'ethology'. Anyone who uses this approach can be called an 'ethologist', though there are several different kinds of ethologist, with different approaches and interests. 'Ethology' just means the study of behaviour, but it has come to refer particularly to the way of studying behaviour that treats it as a biological entity. Often, it involves looking at the behaviour of animals other than human beings. Although many psychologists would say they study behaviour, they would not usually call themselves ethologists. In effect, ethology is the study of behaviour seen as part of zoology rather than, say, part of social science or philosophy.

Why does ethology matter? The next few sections of this chapter give my answer to this basic question.

Why does behaviour matter in biology?

In the course of this century there has been a sharp increase in the proportion of the total biological effort devoted to behaviour. Why is this? Is it simply a shift of fashion, or the scientific community catching up on a neglected area? Or is there some more fundamental reason? It seems to me that there is, and that it is quite simple. In this century, biology has had what it did not have before, a coherent theoretical basis. That basis is Darwin's theory of evolution by natural selection. This theory is so basic to all biology that anything which matters to natural selection matters to biology. And behaviour matters, crucially, to natural selection. Let us see why this is so.

Vertebrate life began in water. At some point, we suppose, something a little like a modern lungfish became adapted to survive the occasional drying out of the pools it lived in. That much could have been a purely physiological adaptation, but it would have had no interesting evolutionary consequences if there had not also been a change in behaviour: the animal started to move around on dry land, feeding or avoiding predators. From that crucial behavioural step all land vertebrates spring. Without it, there would have been no reason for that primitive protoamphibian to develop anything more than a capacity to survive, passively, out of water for a shorter or longer time.

Almost all other interesting evolutionary developments have a behavioural component in the same sort of way. In terms of evolution, changes in behaviour and changes in anatomical structure or physiological capacity go hand in hand. It is this evolutionary fact that gives behaviour its central importance in modern biology. It also makes it inevitable that a biological approach to behaviour will be an evolutionary approach.

Why does a biological approach matter in psychology?

Why should anyone except a biologist be interested in an evolutionary approach to behaviour? After all, many readers of this book will be psychologists rather than biologists, or lay people not committed to any discipline. Why should the evolution of behaviour matter to them?

The first reason is a negative one. We have to be interested because so many people have been in the past. Explanations and justifications of human behaviour in terms of our supposed evolutionary past, in terms of what other animals from rats and pigeons through geese and gulls to chimpanzees do - these abound in both the popular and the scientific literature. If this book can correct some of the wilder speculations that are at present in circulation, it will have more than served its turn.

More positively, though, an evolutionary explanation is often a plausible starter as a way of accounting for behaviour. Take a contentious example, the tendency for men to be more aggressive than women. Male aggressiveness is an obvious general tendency throughout almost all vertebrates. It may or may not be the case that male humans are aggressive for the same reasons as male chimpanzees, male rats and male mallards; but if we can understand the functions and mechanisms of male aggression in mallards, rats and chimpanzees (and we can), we at least have some hypotheses to start testing in the human case.

But the simplest, and for me the most important, reason for being interested in the evolutionary account of behaviour is simply that we cannot understand what it is to be human unless we know what it is to be other than human. There is no doubt that the human species is unique, if only because every species is unique, but unless we know quite a lot about the other species of animal that share our world, we are likely to be gravely mistaken about the precise nature of human uniqueness.

Four ways of applying the biology of behaviour

Understanding animal behaviour therefore seems to me to be an essential part of understanding ourselves. That is a somewhat rarefied reason for being interested in ethology, however. Are there any more practical gains to be expected from studying animal behaviour? I see four ways in which ethology is an applied science.

The first is limited in scope but is not open to serious dispute. Human beings have to interact with animals in a variety of ways. On farms, in zoos and in wildlife reserves, animals have to be managed, for our purposes and often also for their own good. It should not need arguing that a knowledge of their behaviour can make for better husbandry. An obvious example involves mating behaviours in endangered species: there are many species that will not survive the next few decades unless they can be induced to breed in captivity or near captivity, and unless we know quite a bit about their normal mating procedures, we may be unable to provide the right conditions for that to happen.

A second relatively uncontroversial application of ethology is the use of its experimental and observational methods, originally developed for use with animals, in the study of human behaviour. There has been a spate of this so-called 'human ethology' in the past decade, and some of it at least has been both novel and interesting. We shall see that the ethologist's chief methodological tool is close and detailed observation, and this has also characterized the human ethologists' work. A few psychologists may find the introduction of ethological methods and terminology gimmicky or even threatening, but on the whole this kind of application of ethology is working well, especially in studies of babies and young children.

The third way of applying ethology is closely linked to the second, but is much more controversial. It involves taking over ideas and concepts developed in ethology and incorporating them into psychological theory. There have been some successful transplants along these lines. For example, the concept of'individual distance', the distance which two individuals of the same species always try to keep between each other, started in Hediger's analysis of the behaviour of zoo animals, but (under the alias of 'personal space') it has now acquired a key place within social and environmental psychology. When we look at real examples like this, though, we find that there is not and should not be any automatic acceptance of ethological ideas within psychology. It is only if those ideas prove themselves useful, when tested against human, psychological data, that they are taken up and developed within the mainstream of psychology.

The last and most questionable way of applying ethology is the direct extrapolation of results from studies of animal behaviour to human affairs. It is an immensely attractive game, which any number can play. Robert Ardrey, Desmond Morris, even such paramount figures as Konrad Lorenz and E.O. Wilson, all have published popular or semi-popular books trying to make this kind of extrapolation. It goes on in the sober-sided learned journals as well. It is good fun, for authors and readers alike. It may suggest all sorts of testable hypotheses; it may also raise all sorts of hackles, and both those are often useful things to do. But they are not, in themselves, science, and they should not be allowed to cloak themselves in scientific respectability. They are not science fiction either, but something in between; science myth, perhaps.

Such speculation is quite harmless so long as people recognize it for what it is. There is a certain amount of it in this book, because it is almost impossible to resist the temptation to draw- analogies from what we know about animal behaviour to what we should like to explain about human behaviour. But I have tried to let it be clear when I am stopping being scientific and offering a little fun.

Key concepts of evolutionary theory

I have said that a biological approach to behaviour is bound to be an evolutionary approach. That is in any case what we usually want when we are considering applying ethology to human affairs: evolution offers us answers to some of our most profound questions about ourselves, the questions that begin, 'Why ...?' Why are men more aggressive than women? Why do we smile when we are pleased and frown when we are angry? Why do we, alone among animals, speak? We have seen that we need to be cautious in applying ethology to answer such questions, but that does not mean we should make no attempt to find answers at all.

But if we are going to give evolution a central role in our thinking, we had better make sure that we are operating with the genuine article, not with some half-understood misrepresentation of Darwin's theory. Almost everyone knows roughly what the theory of evolution says, but there are several ways in which that rough understanding needs to be polished up if we are to make sense of either animal or human behaviour.

The first step is to be clear about the meanings of words. 'Evolution' just means gradual rather than sudden formation: Darwin meant that species are formed from other species by a series of linked steps, rather than springing forth from nowhere, or from the hand of God, in the form in which we now see them. By the phrase 'natural selection', Darwin meant that there are natural processes that operate in the same way as human breeders do, perpetuating some lines in preference to others and so producing new varieties of animal. A common way of talking about natural selection is to refer to 'the survival of the fittest'; nowadays, this is simply treated as a definition of'fitness'. To a biologist, a relatively 'fit' animal is simply one that leaves more descendants than some other animal of the same species (which is therefore relatively less fit).

So much for the basic terms of the theory. A few other words crop up so often that they need to be explained here. 'Adaptedness' is the property of being well suited to the environment an organism lives in. It does not mean the same as 'fitness'. The better adapted an animal is, the fitter it is likely to be, but it is possible to be fit without being well adapted, and well adapted without being fit - it all depends on what competition there is. The precise environment to which an animal is adapted is called its 'ecological niche'; a law formulated by Gause (1934) states that no two species can occupy the same niche. A 'selective pressure' is any property of the environment, particularly any property of the ecological niche, that tends to favour one form of a species rather than a different form of the same species; that is to say, it is a factor that makes some animals fit and others less fit. Finally, what precisely do we mean by a 'species'? We say that two animals are of different species if they are normally prevented from breeding together and producing fertile young of both sexes. Biologists will realize that this definition leaks a bit around the edges (what about asexually reproducing organisms, for example?), but it is good enough for this book. It means that the species is the range of gene exchange, and hence the field within which evolution can operate. If one cat's genes undergo a change (what we call a 'mutation'), and this produces a new, advantageous pattern of behaviour in that cat's offspring, then in principle evolutionary processes can spread that new behaviour to all the cats of some generation to come. There is no evolutionary way in which the new behaviour can appear in dogs.

Misunderstandings about evolution

There are several ways in which people thinking about behaviour sometimes misunderstand evolutionary theory. The most basic error is to suppose that evolution will always produce the best possible solution to any environmental problem - in the terms just introduced, that organisms will always be ideally adapted to their ecological niches. This is a mistake in several different ways.

There are, in fact, sound reasons why evolution is unlikely to produce the best possible solution. Chief among them is the fact that it is a historical process. It may not be possible to reach the best possible solution from the point at which an evolutionary-process happens to start. The historical nature of the evolutionary process has been strongly emphasized by Gould and Lewontin (1979), who argue that two species may reach quite different, equally good, solutions to similar problems because they took different evolutionary routes; and that this makes interpretations of species differences in terms of adaptiveness extremely hazardous.

Also, by the 'best possible solution', people often mean what is best for the species as a whole. But evolution does not take place by competition between one species and another. It takes place by competition between one individual and another (or, more precisely, one gene and another) within a species. What evolves will therefore be what is good for individuals, not what is good for the species. This is a central theme of the most recent biological approach to behaviour, known as sociobiology. Earlier authors were not always too clear on it. We shall return to this point many times in the course of this book.

A second misconception about evolution is to suppose that, because the word 'evolution' implies gradual change (it is often opposed to 'revolution'), evolutionary change is going on at a more or less constant rate, with new species being produced at roughly the same low frequency throughout the history of life. But this is not what happens at all. Instead, one species of animals makes a crucial advance, and a great range of species promptly differentiate from it to fill a great number of niches, probably displacing earlier species in the process. Evolution of new species further alters the environment for other unrelated species, and so applies new selective pressures which may trigger off yet more rapid differentiation. Evolutionary biologists think of the history of life as consisting of a series of 'punctuated equilibria', with long periods during which relatively few new species appear followed by 'adaptive radiations' as entire new groups evolve. The fossil record supports this picture.

One final misconception must be nailed before we proceed to look at some criticisms of evolutionary theory. To produce an evolutionary explanation of any behavioural phenomenon is to show that it is 'natural'. That is what the word natural means, if it means anything at all when applied to behaviour. All too often, people will proceed to draw the conclusion that because some kind of behaviour is natural, it must also be morally justifiable or even to be positively sought after, and in any case that it will inevitably occur. In the course of this book, we shall find that it may be natural for men to kill their stepchildren, women to be unfaithful to loyal husbands, children to rob their siblings. Neither I nor any evolutionary biologist is saying that these things are desirable, justifiable or inevitable; simply that they are tendencies that exist in people. Some critics have understood that much, but seem to believe that if such tendencies are natural, the less said about the fact the better. This too is untenable. Unpalatable truths are better faced; then it becomes possible to do something about them. It is scarcely a new idea to western thought that human beings have some deplorable behavioural tendencies, for if we did not we should have no need of moral principles.

Criticisms of evolutionary theory

Although evolution is the central idea in modern biology, that does not mean that it is, or should be, above criticism. The almost religious attachment of some biologists to evolution is inappropriate, for it is conceivable that Darwin's theory could one day be replaced by something else. Even now, in some obscure laboratory, a palaeontologist could be piecing together conclusive evidence that all living species were created a few thousand years ago by genetic engineers from Mars, who then hopped into their flying saucers and flew away, pausing only to scatter a few misleading fossils. Don't laugh: it's a logical possibility. Any scientific theory can always be superseded.

The commonest criticism of evolutionary theory in fact argues that it is losing this provisional quality, which always characterizes scientific ideas, and is becoming a sort of super-flexible dogma, into which any facts whatsoever can be fitted.

This objection must always be borne in mind, as a warning against what we can call 'armchair adaptationism' - thinking up evolutionary explanations for behaviour without considering how they could ever be checked against data. This does indeed lead to a pseudo-science of no interest. The sophisticated way of putting this kind of objection is to appeal to the ideas of Sir Karl Popper (1959) and argue that evolutionary theory cannot be scientific because it is not falsifiable - there is no conceivable set of observations that could show it to be wrong. The Popperian critic of an evolutionary approach to behaviour would say that there is no behaviour for which we could not think up an evolutionary explanation. Once again, this is true if, but only if, we let ourselves slide into armchair adaptation ism. What we have to do is guard, jealously, the empirical content of our theorizing - the extent to which it says something about the real world that is open to an empirical test, that is to being examined by observation and experiment rather than just by logical analysis.

A second kind of criticism focuses either on the idea of gradual change implicit in the word 'evolution', or on the phrase 'natural selection', with its implication that particular, fit individuals (usually the best-adapted ones) will spread their characteristics to succeeding generations. From time to time one hears reports of evidence that species may have developed from each other by sudden jumps, or by purely random changes in the 'gene pool' (the stock of genes represented in the population), and that speciation by either of these routes casts doubt on Darwin's theories. Both these processes are in fact predicted by modern evolutionary theory - they are known as 'saltation' and 'genetic drift' respectively, and both are known to occur. All genetic change must have at least some random component, and we have already seen that new species do not emerge at a constant rate from millennium to millennium. There is room for argument about the quantitative importance of genetic drift and the size of the genetic 'jumps' that make the important contributions to evolution. But the most fervent supporters of drift and saltation do not see themselves as setting up an alternative to Darwinism; on the contrary, some of them claim to be returning to the true s...

Table of contents

• Cover
• Title
• Copyright
• Original Title
• Original Copyright
• Dedication
• Contents
• Preface
• 1 A biological approach to behaviour
• 2 Instinct
• 3 The evolution of instincts
• 4 The evolution of societies
• 5 Males, females and offspring
• 6 Learning, intelligence and culture
• 7 The talking animal
• Suggestions for further reading
• References and name index
• Subject index