Chapter 5: The Process Theory of Evolution and Notes on The Evolution Of Mind by C. H. Waddington
C. H. Waddington taught and did research at the Department of Genetics in the University of Edinburgh. He died in 1975.
The Theory of Evolution has undergone rapid changes during this century. Some of these changes seem to me to be drastic enough to qualify as alterations of paradigm in the sense of Kuhn. Certainly the change at the beginning of the century was of that nature. Previous to that time any theories of heredity which existed -- there was nothing very highly developed -- were in terms of statistical aggregates. For instance, Pearson and Galton had some sort of theories based on the resemblances and differences between collections of individuals standing in different relations to one another, as sibs, cousins and so on. The introduction of Mendelism changed the emphasis entirely from a consideration of populations in statistical terms to a consideration of the offspring resulting from individual crosses between identified individual parents. It was by experiments of this kind that genes were identified and the process of gene mutation discovered. Evolution was not of major interest to most of these biologists, but insofar as they had a theory of it, it was a theory in terms of mutations of individual genes, carried by individual organisms and submitted to natural selection. It was not until some two decades later that the people started seriously to consider evolution, when of course it became clear that they had to think in terms of populations of individuals. However, the first workers in this field, such as Haldane and Fisher from the theoretical point of view, and biologists such as Timofeef-Ressovsky, Dubinin and others, in practical field investigations, were still thinking mainly in terms of individual genes. This was the phase of evolutionary thinking about which the term neo-Darwinist was first used. However, this first phase fairly rapidly was superseded by a second, in which Sewall Wright and Theodosius Dobzhansky were the two key figures, both of them insisting on the importance of thinking of populations of many genes, as well as populations of many individuals. This can properly be called neo-Darwinism of the second and fully developed kind.
A characteristic of all this neo-Darwinist thinking is that it effectively did not pay any attention to the phenotype. In its mathematics, the selection coefficients are attached to genes or genotypes. Now, selection of course does not act directly on genes or genotypes, but on phenotypes, and in the formation of these phenotypes environmental factors have an influence as well as genetic ones. I have for many years been trying to introduce a new paradigm which takes the phenotype seriously. Charles Birch seems to think this can also be lumped in together with neo-Darwinism, and speaks of it as part of the orthodox modem theory of evolution. I should like to see it accepted as orthodox, but I do not believe it as yet. Very few other authors, with the exception perhaps of Schmalhausen and a few of his students, have done anything more than pay the merest lip-service to the idea that selection operates on phenotypes. The conventional view surely still is that ‘acquired characters,’ since they are not inherited by individuals, have nothing to do with evolution. Anyone who suggests anything else is dismissed by many leading biologists, such as Monod and Luria, as a Lamarckist if not a Lysenkoist.
This rejection persists because people persist in thinking in terms of individuals rather than of populations. If an individual acquires a character during its lifetime, that does not increase the probability that its offspring will exhibit the character; but if the development of some members of a population are affected by the environment in ways which improve their chance of leaving offspring, this will obviously increase their contribution to later generations, that is to say, their natural selective value; and the frequency of that character in later generations will be increased, not by any physiological or genetical change, but by the operation of selection. In fact we can say that natural selection will favour organisms which acquire useful characteristics.
Now, if one combines this simple fact with a well-known but rather more unexpected one, namely that developmental processes are difficult to alter, one finishes up with a very powerful evolutionary mechanism. Say we have a population of animals which has to meet some new challenge offered to it by an altered environment; there may be some individuals in the population whose development is changed by the environment in a way which makes them better able to deal with the challenge -- they show a capacity for adaptive modification. They will, therefore, be favoured by natural selection. After this selection has gone on for some considerable number of generations, the new pathways of development will have gradually acquired a more pronounced chreodic character, which can itself be difficult to modify. In fact, should the environment now revert to what it was before the whole process started, the organism may well go on developing in the way in which it adapted to the changing environment. This process, which I have called genetic assimilation, gives exactly the same end-result as the theory proposed by Lamarck, at one time espoused by Darwin but rejected by modern biology, of the direct inheritance of acquired characters.
The fact that, by a slightly more sophisticated development of modern biology, we have come across an evolutionary mechanism which can produce the same effect is, I think, not without importance in relation to mind. It shows how a behavioural pattern, which in an earlier evolutionary stage emerged only in the actual presence of a certain environmental situation, might, if it was selected as useful over many generations, become habituated to a chreodic developmental pathway which would operate even in the absence of that environmental situation. It is because of the existence of this mechanism that I am not alarmed by the suggestions, of people like Chomsky, that man has an ‘innate’ capacity for the use of language. If at an early stage in his evolution it was useful for an individual to be able to adapt to a language-using community, i.e., to learn language as fast as possible, selection for this capacity might well have brought about a genetic assimilation of at least the bases for what had originally been only a learned adaptive response.
Another great oversimplification of the neo-Darwinist statement of evolution implies that the thing that is being selected (genotype according to the conventional statement, phenotype as I suggest) finds itself inevitably subjected to certain selective pressures arising from ‘its environment.’ In fact most higher organisms select their environment before they allow the environment to select them. Release a hare and a rabbit in the middle of a field; the rabbit will run off to the hedge and live its life there, while the hare will be content to live its life in the open field. Even plants, in a more rudimentary way, make some sort of selection of the circumstances in which they will develop. If a seed falls on stony ground in the desert, it simply refuses to germinate until the next shower of rain comes along and gives it an environment at least somewhat appropriate to its needs. However, there can be no doubt that this reciprocal relationship of mutual feedback, between an organism which selects an environment and an environment which then selects the most efficient organisms, assumes greater importance as we go higher up the evolutionary scale.
In particular, I think it must be of crucial importance in the evolution of behavioural patterns and of anything which we might call a mind. For instance, at some point in their evolutionary history, the ancestors of horses began to eat primarily the grasses of open plains, and not for instance the leaves of shrubs. They then had to deal with the possibility of being attacked by carnivores, and they came to deal with this threat by running away rather than by standing on their hind legs and trying to fight off the attack with their front feet, as giraffes do, for instance. One might somewhat figuratively say that they had ‘chosen’ to inhabit one type of environment rather than the other, and to adopt one type of strategy against predators rather than another. But, of course, that mode of expression should not be taken to imply a conscious process of choice. However, once evolution had started to go in those directions, this defined the character of the natural selection that would be exerted, and evolutionary changes went on in the same direction for a very long period. The mind of the horse has evolved into that of a plains-dwelling fleet-footed animal, which runs away from its enemies. The mind of the buffalo, on the other hand, is that of a plains-dweller which faces its enemies and charges them.
Such types of animal minds, evolved in relation to a reciprocal interaction between the selection of environment by animal and of animal by environment, are what we refer to rather crudely as instincts. An instinct is a pattern of behaviour which is to a major extent dependent on the hereditary constitution of the animal. It is a mistake, however, to think that it is in all cases wholly dependent on the genetic constitution and that the environment plays no role in shaping the behaviour. I will mention only one example which illustrates two ways in which the environment is important in the development of instinct. Weaver birds build elaborate nests consisting of a completely enclosed nest chamber, approached through a tubular entrance. Each species of weaver birds builds nests of a different shape. I do not know why different species should adopt differently shaped homes, but the fact that they do shows that there is a very strong hereditary element in their behaviour. However, birds build a better finished, and more competently constructed, nest in their second year than they do in their first. There is, therefore, an element of learning involved. Consider the problem of a bird approaching a half-finished nest. It has got to decide just how to weave the piece of straw in its beak in amongst the other pieces of straw. It has been found that there are certain kinds of weaving stitches which it can do, but it never, for instance, ties a proper knot. However, it has always to discover some way of adapting the particular types of weaving process at its command to the particular circumstances which confront it. This involves highly adaptive behaviour -- much more adaptive to the environment than one might imagine if one simply wrote the instincts down as hereditary.
We may say that instinctive behaviour is behaviour related to a rather well-defined goal, but often demanding a more flexible adaptive type of behaviour, including the possibility of learning from experience, in deciding exactly how that goal shall be reached. I myself should not refuse to use the word mind in connection with organisms which showed this type of behaviour. The main point I should like to emphasize is that, in such cases, the goal towards which the instinct drives has certainly not been decided by any conscious choice of the organism, but by this subtle evolutionary process of natural selection within a framework which has been set by the previously existing instinctive behaviour.
But if an animal behaves in accordance with one definite unalterable goal, how much of a mind would we be inclined to attribute to it? Surely, we would not think it was being very clever. In fact, we might be tempted to say it was indulging in ‘mindless repetition.’ We would be much more tempted to think the animal had a worthwhile mind if it had at least two goals, and followed one or the other in appropriate circumstances.
Thus the evolution of the mind must involve not only the formation of a goal, but also the development of alternative goals, and the ability to pick the appropriate goal under particular circumstances.
The problem of mind -- being intelligent -- at this level is not only to find new ways of attaining already accepted goals, but puts a premium on the still greater flexibility of discovering new goals.
I will tell the tale of the evolutionary origin of the birds -- or rather, one of the more plausible tales, because the experts have not yet quite decided exactly how it did happen. But one of the ways it may have happened concerns a group of little reptiles, rather like lizards, which had larger hind legs than forelegs, and which normally ran about on these back legs. Suppose they started using their forelegs to work up speed when they were running away from a nasty bigger reptile who was trying to catch them. And suppose the scales on the arms grew longer, into something a bit like feathers, to help them get the benefit of beating the air effectively to push them along. And natural selection pushed this development further until, one day, some of them found themselves taking off and becoming airborne. It must have been very disconcerting; they probably ran the risk of crashing in considerable disorder, and getting gobbled up. But a really clever little lizard, full of mind, must have said "Hey, we’ve got something here," and set about finding how to fly. To attain this brand new goal, he may have had to change quite a lot of his previous routines; for instance, beating his arm-wings in unison instead of one after the other in time with his legs. In order that such an evolution could be possible, his mind had to be able to do two things. It had to be able to reorganize itself around a new sub-goal, to fly, within its old main goal, to escape; and it had to be able to re-arrange its detailed activities so as to achieve this new sub-goal, to change the timing of its arm movements, for example.
Finally, one might ask the question, out of what kind of stuff is mind constructed? Recently, even those who accept physico-chemical entities as a basis of all scientific knowledge have realized that something more may be involved in them than the properties of mass, energy, etc., attributed to them in classical theory. This further component might be referred to as ‘specificity’ of spatio-temporal configuration. In the last twenty years or so, mathematicians and engineers have attempted to replace the rather undefined term ‘specificity,’ which had been much used by biologists earlier, with a more precisely defined notion of ‘information.’ Unfortunately, in order to achieve a precise definition capable of being utilized in a mathematical logical system, they have ‘purified’ the notion until it has become almost useless in connections with biology, or indeed in almost all contexts except that of messages -- which was the main business of the Bell Telephone laboratories in which the originator of the theory, Claude Shannon, was employed. ‘Information,’ as it emerged into the world of mathematics, is a measure of the degree of selection which has been employed in choosing some particular configuration out of a closed universe of possible configurations. It is concerned only with the specificity within a particular universe of possible specificities. For instance, the amount of ‘information’ contained in the letter A is less if it is chosen out of the English alphabet of 26 characters than if it is chosen out of the Russian alphabet with 29. Moreover, the amount of ‘information,’ in this sense, has nothing whatever to do with bringing about any action outside the closed universe; that is to say, it has nothing to do with ‘meaning,’ in any sense of that term. The information content of a message written in English words is just the specificity of the string of letters in which the words are spelt. Consider the two messages:
MEET HIGH MARKET TWELVE TEN
MEAT HIGH MARKET TWELVE TON
The differences in ‘information’ are simply that the third letter from the beginning is an E in one and an A in the other, and the penultimate letter is E in one and O in the second. ‘Information’ Theory has nothing whatever to say about the fact that the first is obviously about an appointment to meet at the corner of High Street and Market Street, and the second is a message from a wholesaler that the stocks are going off and had better be got rid of as quickly as possible.
This limitation in the meaning of ‘information’ made it possible to develop a mathematical theory which is very useful in connection with transmission of messages along channels, but effectively mined it as a word which is useful to apply in wider contexts. Rather unfortunately, the mathematical theory assigned, to the measure of ‘quantity of information,’ a formula which was identical to algebraic form with one of the most famous formulae of thermo-dynamics, namely that for entropy. This at first led Shannon to identify the amount of information given out by a source with its entropy. Later Warren Weaver developed an alternative interpretation, that the quantity of information contained in a message is the negative of its entropy. It was Weaver’s rather than Shannon’s interpretation which became fashionable, and the new word ‘negentropy’ was invented to mean ‘quantity of information or negative entropy.’
The relevance of all this is that there is no doubt that reactions in living systems are very much concerned with the specificity rather than the mass or energy of the components. It is the specific arrangement of nucleotides along the chain of DNA which determines what that gene will do; it is the specific shape in three dimensions of a protein molecule which determines what sort of enzyme activity it will exhibit, and there are many other examples. For a time it became fashionable to discuss this sort of specificity in terms of negentrophy, and some of the most penetrating minds, when they turned from physics to biology, were deceived for a time. Thus Schroedinger, in his elegant essay, What is Life? in 1944, indulged in aphorisms such as ‘life feeds on negentrophy.’ However, he soon came to realize that this is an inadequate way of looking at the situation, and he withdrew or at least greatly qualified the remark in the later editions of his book.
The main point is that the specificity with which biology is so deeply concerned is not a static specificity, with no meaning outside itself. It is rather the possibility of bringing about, or tending to bring about, a certain type of activity in appropriate things which react with it. It is, in fact, a specificity of instruction, the imparting of one particular program, or algorithm. Several authors, including, for instance, H. C. Longuet-Higgins, insist that language has basically to do with programs or instructions, rather than with imparting descriptions from which nothing follows.
Of course, the word ‘information,’ as it is used in ordinary speech, often has some implication that the information will be useful as a guide to action. But it is pretty ambiguous in this context. In fact, during World War II, there was a useful distinction made in the slang of the RAF, which distinguished the ‘info,’ a lot of boring rigmarole about useless facts, from the ‘gen,’ the real stuff you needed to know to tell you how to operate. When we say that biological systems work by means of the programs or instructions incorporated in their components, this is a long-winded way of saying that it’s the gen, not the info, that matters for them. It is not negentropy they feed on, but it might have made some sort of sense to call it gentrophy, if I may coin an unnecessary word.
It is not only biological systems that feed on gen. There are some physico-chemical systems, which no one would dream of calling living, which very clearly do so too (possibly they all do, but I will not pursue this point here). Consider the minerals making up that, at first sight, boring material, clay. They have been discussed in some detail from this point of view by Cairns Smith in his book, The Life Puzzle. Clay minerals consist of crystals in which atoms of silicon, oxygen and a number of metals, such as aluminum, iron and various rarer and less frequent ones, are arranged in a three-dimensional lattice. The lattice is such that at any given time in the growth of the crystal its boundary is a flat two-dimensional plan, with a particular arrangement of these atoms at certain points on it. Now, the forces at work are not terribly choosy about which particular atom goes into which place. At one particular point on the surface there might be an atom of aluminum or alternatively there might be an atom of iron, or some other substance. "Ha!" the information theorists will say, "This surface can encode a great deal of ‘information’." So it can, but the point is that this is not mere info, it is gen. If there is iron instead of aluminium at point X, and the crystal is in a solution which allows it to grow by the deposition of a new layer of atoms on top of the old one, it is much more likely that another iron atom will take this place in the lattice of the next layer. The presence of iron at X is an instruction for building the next layer.
Whatever we imagine the first living systems to have been like, they must have been even more deeply involved in a traffic of instructions. Any type of hereditary material, be it DNA or anything else, which can be transmitted from one ancestral system to two or more daughter systems, must in effect contain instructions for its own copying. Moreover, in all the living things as they are on this earth, the copying system is carried out by mechanisms, such as enzymes, which operate by means of instructions built into them. Finally, systems which we consider worthy candidates to be granted the name ‘living’ differ from things like clay minerals in that they contain instructions, not only for copying, but for the elaboration of structures which can actively Operate on surrounding materials. These new embodiments are what geneticists speak of as the phenotype. The crucial role of instruction-generated phenotypes as a fundamental aspect of living systems has been a dominant theme in recent discussions of the theory of general biology (see the four volumes entitled Towards a Theoretical Biology, edited by C. H. Waddington, Edinburgh University Press).
The early stages in the evolution of life, therefore, involve not only physico-chemical mass, energy, atoms and so on, but also specific instructions. We find the firmest evidence of mind when we look at the other end of evolution, as in our ‘occasions of experience,’ and we are again, of course, fundamentally involved in a traffic of instructions. A knower does not merely sit down before the known and observe it without consent or response. On the contrary, he brings to it certain predispositions, or interests, and observes certain characteristics more than others. The content he finds in the occasion demands a response. As Popper has put it, the ‘prior knowledge’ with which he comes to the occasion is such that what he receives from it is not mere information but instructions or challenges.
In the light of this discussion, the evolution of mind appears as a transition from the instructional traffic involved in the very simplest living things, or even in the pre-biotic systems such as clays, to the much more complex traffic of instructions involved in our own occasions of experience. We can see two ends of the evolutionary range in similar terms. We have evaded the dilemma of considering the beginning of the evolutionary process as depending on nothing but atoms, forces and physicochemical factors, and the other end as involving something of a totally different character we call ‘mind.’ One recent author who has advanced a similar view is Stephen Black. In his book, The Nature of Life, he also draws attention to the importance of instructional traffic in all the processes of life (unfortunately he has not escaped from the fashionable convention of speaking of information when what he really means is instructions). His next step, however, is to expand the use of the word ‘mind’ to cover the whole range of situations involving instructional traffic from the very simplest to the most complex. This is hardly satisfactory, since, as we have seen, the simplest such situations occur in things like clay minerals, and it is hardly illuminating to speak of them having minds. When God fashioned us out of clay, he may have picked the right material to start from, but there was still a lot to do. I have briefly discussed earlier in this paper the nature of the evolutionary processes which have led from the simpler situations to the more complex ones.
The editors asked me to provide some account of points made during discussions about evolution and mind. Since pressure of other work has prevented my writing a special essay on this, I have put together the gist of what I said by taking extracts from my contributions to the Gifford Lectures at Edinburgh University in 1971/2 and 1972/3 (The Nature of Mind and The Development of Mind by A. J. P. Kenny, H. C. Longuet-Higgins, J. R. Lucas and C. H. Waddington; Edinburgh University Press, 1972 and 1973).