What is adaptation?

Front matter

22102371090

T

Med

Preface

This book is a sequel to another, published two years ago, under the title ‘ The Growth of Groups in the Animal Kingdom/ It is not, however, a continuation of the chief subject of the latter, but of a side issue. On the previous occasion, I expressed the opinion that adaptation did not, in itself, need explanation : but certain critics soon inculcated that it was unwise to make such an assertion, without properly defending it. Consequently, I shall here endeavour to show how the need for an explanation of adaptation has arisen, and why such an explanation seems unnecessary.

Some critics noticed that I was biassed against the selection theory. Indeed, I was careful to say so at the outset. ‘No one should be biassed,’ they advised; ‘ keep your mind open and wait for evidence.’ But they fail to see that the selection theory, whatever its value, is the expression of a certain bias, a certain mental requirement, the need for an explanation of adaptation.

The tone of much of the criticism, directed against my last book, was as follows — “The selection theory is settled, you cannot alter it. If you have anything to say about evolution, you must take that theory for granted. Even the leaders of the mendelian school ‘ accept the

VI

PREFACE principle of natural selection in its wider import.’ ”* But this is, I think, far from true. They may perhaps accept the theory in its wider import, whatever that may be ; but they do not accept it in itself, as their writings show.

What is the selection theory ? It does not lie merely in the fact of evolution and in the fact of competition. It lies in the proposition that competition causes evolution and this proposition was made in order to explain adaptation and life in general. It regards organisms as fitting into something, which is called their environment ; somewhat like the wax fits into a seal. It holds that every item in the organism has a corresponding item in the environment, and it holds that this correspondence was brought about by the elimination, from the one side, of all that would not fit. This is the selection theory as commonly understood and it is, I think, impossible for any one person to hold this theory and to believe in the origin from mutants at the same time. Origin from mutants is origin without selection. Darwin himself pointed this out. Some critics carelessly informed their readers that I was ignorant of the fact that Darwin admitted the origin from mutants. I have known it for the last twenty years and I was very careful to say that I knew it, on the second page of my book. Darwin finally admitted that groups of like organisms might sometimes arise directly from sports ; but stated clearly that such events would occur '‘independently of natural selection.” Selection among mutants does not explain adaptation in the least. That is why so many object to

* Sociological Review, July, 1913.

PREFACE

Vll discontinuity in evolution. They need an explanation of adaptation. They see purpose, as a special human attribute, pervading all life and are perplexed thereby.

This book is an attempt to show how such perplexity may be overcome, and that there is nothing in adaptation to be explained. It is not scientific in the usual sense, being influenced considerably by M. Bergson's philosophy.

R. E. L.

Medical College,

Calcutta,

Contents

PAGE

Introduction . i

Chapter I

The relation between adaptation and contrivance, exemplified by contrasting fitness and growth 29

Adaptation causes wonder — The origin of the wonder, which is not

universal 30

Adaptation in its more technical aspects — Adaptation and adaptability — Racial and individual adaptation — The difficulty of explaining the latter 32

The antiquity of adaptability — The personal need of explaining it . 37

The impossibility of unadapted life — Is adaptation superimposed or inherent?— The view that it is superimposed exemplified and discussed — The view that it is inherent advocated, though contrary to the principles of modern science 40

Fitness as egoism 43

Fitness identified with the fact of survival 44

v CHAPTER II

The variety of outlook — The idea of supernature is common to all —

The broad distinction between definite and indefinite conceptions of supernature — The latter exemplified 45

Definite conceptions or explanations of life — Teleology, dominative theism, and the selection theory arise from a similar source and satisfy a similar need 49

Lamarck’s view 54

X

CONTENTS

Chapter III The Origin Of The Need For Explanation

PAGE

Purpose as human and purpose as vital — Fitness as an agency and fitness

as a word — Is the need for explanation real or traditional ? . 56

Teleology and the selection theory are to explain the resemblance between organisms and mechanisms — They therefore depend on the analogy of man the artificer — Hence both are mechanistic in basis — The difference between mechanistic and vitalistic outlook —

The need for explanation arises from wonder at the resemblance between organisms and mechanisms and from nothing else — The mechanist subordinates the whole to the part, hence he is perplexed and needs explanation — The vitalist subordinates the part to the whole and is not perplexed 60

The unity of life, not yet fully admitted — The need for explanation is

the result of not admitting it 65

The vitalistic outlook long established both in the West and the East . 66

Chapter IV Two Views Of Evolution, Summary And Acknowledgment

The two views of evolution, their incompatibility 68

Evolution analogous to constructive process, having therefore a cause

and a climax — Evolution as reality without cause and climax . . 69

Summary of foregoing 73

Acknowledgment 78

Chapter V

The difference between explaining and seeking for an explanation . . 82

Views of supernature — Attempts to know it — The principle of grouping

— Three importa?it instincts or intuitions defined 83

Preliminary defence of the principle of discontinuity as applied to

intuition 86

I

CONTENTS xi

PAGE

Preliminary account of the three intuitions as defined 87

Amplification of each in turn — The first — The second — The third . . 88

The appearance of the three intuitions in the development of the individual — A further defence of them — The second is dualism, the third is monism — The third intuition necessarily accompanies the realization of evolution 95

The importance of intuition in human life — The necessity of regarding

it as discontinuous loo

Various objections considered — The conventionality of the terms birth maturity and species — Can what is here called intuition be implanted by teaching or imitation? — The phrase or means of expression is passed from man to man, but not the intuition — The same intuition may be expressed by two different phrases *103

The validity of these principles, viz. the importance of intuition and the necessity of regarding it as discontinuous, is already largely admitted — Examples of such admissions 105

Examples of the same intuition expressed by two different terminologies 106

Living things are adapted to their surroundings. If they were not so they could not live. It is therefore impossible that they should be otherwise. All are agreed that adaptation is a primary condition of life. This fact, however, does not produce the same effect on all persons. To some, perhaps to most, it appears as a problem requiring solution. That it is possible to look at adaptation without seeing in it a problem, is a fact that needs emphasis.

There is no doubt that we shall gradually attain a deeper insight into life, but we do not know in the least the direction in which we shall move to attain it. It is, therefore, unwise to see a particular problem in that which we do not know, to ask ourselves a particular question concerning it. But this we do, whenever we regard adaptation as a problem. We ask the question — * How is it that the man-like activity called purpose is apparent in every phase of life ? ' It has long been the custom to ask this question, but it is doubtful whether it is more than a custom to do so, at the present day. It is by no means certain that the majority actually feel it as a problem.

There may be but few, who think definitely that adaptation is not a problem ; but there is certainly a

B

WHAT IS ADAPTATION?

tendency among modern biologists to turn from the subject, a feeling that discussion concerning it gives no result.

Some are fully satisfied with the theory of natural selection as an explanation of adaptation. Others, though less satisfied with this theory, defend it on the ground that it is the best available. They find in it a relief from a more obviously anthropic theism which is repugnant to them. But there is, I believe, a third party, who regard the whole subject with indifference and if their point of view were to be more fully expressed, it would be found that they had little or no curiosity concerning the cause of adaptation. This view has the disadvantage of being somewhat indefinite, but when it is supplemented by an understanding of how the problem of adaptation has arisen, it may develop into a conviction that adaptation is not a problem.

We shall consider, then, how the problem has arisen. It is evident that the idea of adaptation, suitability, or fitness, is very ancient, and it seems no less evident that the idea must first have arisen in connection with contrivance. There was a time when man first began to make things, and the things made must often have been related to his essential needs, just as a bird’s nest is related to the need of its builder. The thought, expressed in the words suitable, useful or excellent, must first have arisen in connection with those implements that gave satisfaction and were therefore somewhat permanent. Subsequently, and probably at a much later date, man noticed a similarity between contrivances and organisms, a similarity arising from the fact that both were suited to circumstances. This led to the view of God as artificer. It is difficult to say when this was first thought of. The idea is, of course, very old. Xenophon relates how he heard Socrates discoursing with a pupil about adaptation, “ I no longer have any doubt, replied Aristodemus ; and, indeed, the more I consider it, the more evident it appears to me that man must be the masterpiece of some great artificer.” 1 Although this idea is ancient, it does not appear very prominent until more modern times, as for example in the writings of Paley. Such doctrine is commonly termed teleology. Generally speaking, however, God is far more often represented in sacred writings as king or father, than as artificer.

If it had not been for teleology, it is evident that the theory of natural selection as an explanation of life would be meaningless. This has been emphasised by some of the most strenuous advocates of the selection theory, as well as by their opponents.

It may be that modern scepticism, concerning natural selection, is due to the fact that the younger generation were not sufficiently imbued with teleological principles in their early youth. It is certain that if the theory of selection is to be made intelligible to the fresh mind, the teacher must mention the idea of God as artificer, before introducing the spirit of competition as a substitute for that idea.

Let us take the case of a teacher of biology, whose duty it might be (under the regulations of some University) to introduce the theory of natural selection to minds free from philosophical perplexity. If he is to be intelligible, he must begin by describing adaptation, although

WHAT IS ADAPTATION?

many of his listeners would be acquainted with it in a general way. He must then proceed to show how the theory affords an explanation. But if one of his audience asked why it was necessary to explain this obvious fact, he would find it difficult to reply. He might point out that they had come to him to be taught biology, and that to explain adaptation was one of the customs of that science. Perhaps this would be the best way out of his difficulty, for there is only one other reply, which would lead him into further difficulties. He might say, — * We require it as a substitute for the older explanation, according to which adaptation was caused by an invisible agency, which is comprehensible in so far as it is essentially man-like in ingenuity.’ If to this the pupil replied — * But I was never able to believe that ; of what use then is your substitute to me ? ’ the teacher would find nothing more to say. He may regard such a state of mind as unnatural, because it is unlike his own. He may regard his pupil as insincere, as one purposely falsifying his thoughts in order to attract attention. It is often said that a person holds some such view, for the sake of being peculiar. The saying may be true so far as it goes, but it does not lessen the reality of mental differences. We can forgive anything but insincerity, says some critic, who is lenient to those who wander slightly from his own way of looking at things, but holds those who choose another path to be dishonest. He cannot be like that in reality, so unlike myself, he must be pretending. So we all think at times, when judging others. But let us return to the point Under discussion, the meaning of the word adaptation and its equivalents, purpose, and design.

Some biologists assume a hostile attitude at the sound of the words purpose and design. For example, Adami defined inflammation briefly as “ the local attempt at repair of an injury.” Another author wrote in comment : “ This definition as it stands seems to imply a purposive action which cannot be admitted.” A dozen other examples might be chosen from modern biological literature to illustrate this hostile attitude. In defence of this attitude we are told that to admit design is to ruin science. But this means little. Science is an outcome of man’s restless disposition and will therefore continue to flourish, more especially among those who live outside the tropics.

Let us see what we mean by purpose in the process of inflammation. A man, finding himself exposed to severe weather, will seek shelter. He becomes active in a certain manner for his own benefit. His action is described as purposive ; it is, we may say, typically so. Now let us turn to the other case. A part of a living body, being injured, becomes active in a certain manner. This activity, which is inflammation, is for the benefit of the injured part. But we are told that this activity is not purposive. It is blameworthy to describe it as such. There is, perhaps, no need to assert that the damaged tissue behaves with purpose, but in my opinion, it is utterly unreasonable to assert that the man taking shelter was saved by purpose and at the same time to deny that the tissue was saved by purpose. There is an obvious similarity between the activity of the man and the activity of the tissue. Each behaved in its own manner, for the sake of benefit, in order to continue to

WHAT IS ADAPTATION?

live. If we need a final cause, let us call it x, for the moment, and say that the man was moved by x and the tissue also moved by x, but let us not say that the man moved by purpose and the tissue not by purpose.

Some writers deplore the reintroduction of what they call the mystical element into scientific writings. Any objections brought against the current explanation of evolution are regarded as attempts to reinstate mysticism. The idea of fitness is the essence of the theory of natural selection ; but since fitness is impersonal, some cannot see that it is an entity, as mystical as any other. They speak of fitness as though it were some reality, providing us with an explanation of evolution and adaptation, explaining itself perhaps.

But from the opposite point of view, the theory of natural selection, the basis of which is fitness, does not enlighten us. From this point of view it is inconceivable that there should be a knowable cause of life or evolution.

Those who seek to know the cause of life are under the influence of the thought that a mechanism must be the result of a maker or of a process of manufacture. The teleologist argues that because a watch has had a personal maker, therefore an organism must have had a personal maker. The selectionist argues that because a watch is the result of an intelligible process, therefore an organism must be the result of an intelligible process. The difference between the two arguments is slight in comparison with the resemblance between them.

The fact, that from his earliest days man made tools or simple contrivances, suggested to him that the world must have been made, suggested both the idea of a maker and the idea of making by a process analogous to manufacture. The selectionist implies or even states that domestic pigeons are manufactured, in the sense that they come from the hands of the breeder. Hence, he argues, the same kind of manufacturing process is going on in nature.

Darwin wrote, “ Man does make his artificial breeds, for his selective power is of such importance relatively to that of the slight spontaneous variations/ ’ 2 His meaning is plain. Selection, artificial or natural, is a constructive principle compared with spontaneity which is not a constructive principle. The argument turns on whether breeders make domestic animals or not, and the supposition that they do, arises from the conviction that the forms of life were constructed somehow. But this conviction is not universal, nor can it be acquired by education.

The acceptance of selection, as a universal constructive principle, follows necessarily from a belief in the breeder’s omnipotence — a belief which is due to the need for such a principle, more than to experience. This is illustrated in the following passage, written last year by an eminent zoologist. “ He (Darwin) found that there was no part of an animal or plant which could not be made to vary in any direction which man desired.” 3 Judged from the standpoint of one who is in need of an explanatory principle, the above passage no doubt appears true, but judged merely as a statement of experience, by one who has no such requirement, it appears quite the reverse. Let us examine it for a moment.

WHAT IS ADAPTATION?

There are an immense number of different animals and plants, x. The average number of 4 parts * per individual is large, y. The directions of man’s fancies and desires are also many, z. The above passage states that no less a number than xyz experiments would be performed successfully if attempted, man obtaining his desire in each case. Now, if only ten such experiments had been performed, without a single failure, we should be justified in assuming the probability of the successful performance of the innumerable xyz. But when has one such experiment ever been performed ? The breeder seldom if ever draws up his plan beforehand and works towards its realisation. No one of experience would attempt to make even such a simple contrivance as a horned dog. The cranial peculiarities of domestic animals, which were brought to the public notice as products of the breeders’ constructive skill, were not known to the breeders, even after they had ‘ constructed ’ them, much less before.

It is not easy to find the passage in Darwin’s writings, wherein he made the claim attributed to him in the last quotation. On the contrary, let us see what he thought, in 1878, of the project of raising a fungus-proof potato by artificial selection. “ Altogether the trial would be one requiring much care and extreme patience, as I know from experience with analogous work, and it may be feared that it would be difficult to find any one who would pursue the experiment with sufficient energy.” 4 The doubt whether any one could be found to perform the experiment, is akin to the doubt that it could be performed.

Both teleologist and selectionist see behind the manifestations of life a constructive principle working for an end. Teleology is therefore mechanistic in origin and mechanistic philosophy is teleological. There is no essential difference between them, as others have pointed out. Mechanistic philosophy is usually preferred because it is supposed to be a stimulus. The active mind, however, needs no stimulus. Moreover, it likes to move in its own chosen direction.

Regarding the outlook of teleologist and selectionist as fundamentally the same, there is a great difference between it and another, which may be called vitalistic. From this point of view it is inconceivable that we should know the cause of life and evolution. It is impossible to construct a final or complete cause which is intelligible ; since, in order to be intelligible, any explanation must be constructed out of some idea, the image of some common experience in the daily life of man as he now is. But if our perception of evolution is clear enough, we understand that humanity is in progress. How then can we construct anything complete or final out of that which is in progress, is incomplete, and can have no moment of completion ?

Perhaps the majority of selectionists would say that they do not claim finality for their favourite theory. But that theory has been stretched out and applied just so far as to cover entirely the explanation of the teleologist, to be a complete substitute for it. A narrow-minded selectionist would claim the same degree of finality for his favourite theory, as would an equally narrow-minded teleologist for his. The finality of the selection theory

WHAT IS ADAPTATION?

is displayed in the fact that it was put forward as a substitute for the other view, the first principle of which was its finality.

The vitalist is more impressed by man’s ignorance than are the others. It is scarcely too much to say that he gets from his ignorance of final cause that very satisfaction which the others get from their knowledge of it.

Paradoxical though it may appear, the growth of our knowledge does not seem to lessen our ignorance in such directions, but rather to increase it. To say this is not to decry the pursuit of knowledge, which is very satisfying in itself, besides being praiseworthy and profitable at the present day. Common sense may tell us that to gain knowledge is to diminish ignorance. But that the growth of knowledge increases ignorance becomes obvious, when we compare a man’s outlook with a child’s. A man has more knowledge than a child and a greater sense of ignorance. For some, at all events, it is true that increase of knowledge widens their perception of the unknown, or makes them more aware of their ignorance. Few will deny that Darwin had more experience of nature than the average man, yet his whole writing shows that he felt his ignorance of the subject more than the average man. The relation between patient and physician affords an illustration of this principle. The patient, knowing little or nothing of disease, has usually an exaggerated notion of the physician’s knowledge. The physician at the commencement of his career has often more confidence in his knowledge than after years of experience.

ii

Each new and important discovery does not make one less to be discovered , but makes several more. The field of inquiry widens progressively as knowledge grows.

To explore this widening field we must strike out in various directions. To follow one path through it, a path which leads to the * mystery of mysteries/ may be the choice of some explorers ; but it cannot be the choice of those who see no mystery in the question — ‘ Why or how did purpose, an attribute special to man, come to the whole of life ? ' because it is plain to them that purpose is not an attribute special to man.

This book will be regarded by some as an attempt to make Darwinism appear unnecessary, but the word Darwinism has different meanings, among which one may choose. For my own part, I regard it as the theory of descent accompanied by elimination. Thus, man finds himself widely separated from the rest of the animal kingdom, through the extinction of numerous anthropoid forms. There seems to be no doubt of this and the other distinctive branches of the animal kingdom arrived at their present state in a similar manner. This was the method of origin, but to say that organisms survive because of their fitness in relation to environment and therefore they fit their environment, is to me a custom of language, unquestionable perhaps, but not the expression of important truth that it is to some.

One cannot deny the truth of that which is usually considered to be the essential part of Darwinism, the so-called struggle for existence. The different kinds of organisms are of varying permanence. Some replace

WHAT IS ADAPTATION?

others. That some survive while others perish is an evident truth. It is also true of what we call ideas or intuitions, which may be regarded as expressions of the different kinds of minds. This law of survival has come into prominence through the teaching of Darwin, and as a fact, as a description of events which can be seen to happen, it cannot, I think, be questioned.

No objection can be raised against the efficacy of natural selection, but the very strongest objection may be raised against the infinite extension of that principle. When we think about the efficacy of selection, we call to mind certain occurrences or experiments and thereby become convinced that selection is an efficacious principle. For example, it is well known that when a population has been under a hostile influence for a time it may become changed. It becomes as a whole less susceptible to that hostile influence. The change has no doubt occurred through the elimination of the more susceptible individuals. It was proved by the Plague Commission in India that the rats of a district in which plague had long been endemic were much less susceptible to the disease than those from a district where plague was unknown. Other better-known experiments have shown as well that a race may change as a whole, even in form perhaps, under a hostile influence, for its own benefit.

Let us by all means speak of such experiments as proofs of the efficacy of selection. But now let us consider the advisability of extending the principle of selection until it becomes a complete explanation of the manifold qualities of organisms and of the becoming of new qualities ; that is to say, a complete explanation of life and evolution. An infinite extension of the principle of selection, such as is often advocated, cannot, of course, depend on experience. What then does it depend on ? The answer is obvious. It depends on a certain mental requirement, the well-known need for final explanation. I believe, however, that the need for such explanation, though real in some minds, is traditional or even absent from many others. Its absence, however, is not a part of a general lack of energy or enthusiasm; it implies a want of enthusiasm, merely in one particular direction.

The reader may ask — why, if the selection theory is a source of satisfaction to some, I should wish to oppose it. It is therefore necessary to point out that I am speaking against it only as science. A short experience as a teacher is enough to show that science must be for all. But the selection theory cannot be properly appreciated by all ; only by those who need a final explanation of life. On the first occasion of my introducing the subject to Indian students, I was approached with the request, ‘In regard to natural selection, please write a note on the board.’ The students wanted the words of the formula and I could give them no more. If I said — * the fittest survive, therefore surviving organisms fit their environment,’ some of my listeners might regard it as an important saying, while others might not. With justice might the latter say — ‘ But what has that to do with science ? We have just come from a chemistry lecture where we were shown that water is composed of two gases. Your teaching seems to be of a different order. Where is this fitness you speak of ? ’ Some can see it clearly enough. ‘ Naturally,’ they say, * one kind

WHAT IS ADAPTATION?

replaces another because it is superior or fitter.’ But others cannot grasp either the meaning or value of the word * because ’ in such a connection, and hence the selection theory is not for all, and should not, I think, be taught as science.

If we are to spread Western science over the world, we must at least know the aim of that science. At present there seem to be two distinct aims. The one is towards explanation of life or cosmogony ; the other is towards knowledge of the manifestations of life, with a view to control. Which of these is the higher aim ? Many would say the former. But those who see in any cosmogony a proposition as to how disorder became order, and see also that the apparent necessity for cosmogony arises directly and merely from the fact that man himself is daily converting disorder into order, cannot regard such explanations as the aim of science. Let us set out the rival opinions.