The Ghost in the Machine

  * I shall not bother the reader with technical terms like 'homeoplasy', 'convergence', 'parallelism', which are merely descriptive, but not explanatory.

  The conclusion which emerges from all this is that there must be unitary laws underlying evolutionary variety, permitting unlimited variations on a limited number of themes. Translated into our terminology, this means that the evolutionary process, like all hierarchic operations, is governed by fixed canons, and guided by adaptable strategies. The latter are partly (see below) accounted for by the selective pressures of the environment -- predators, competitors, etc.; but the laws which confine possible evolutionary advances to certain main avenues cannot be defined in terms of these external factors which only enter into action after a change proposed by mutating genes has been approved and passed muster at the successive Kremlin gates of the organism's internal controls. These internal controls define the 'evolutionary canon'.

  Several eminent biologists have in recent years toyed with this idea, but without spelling out its profound implications.* Thus von Bertalanffy wrote: 'While fully appreciating modern selection theory, we nevertheless arrive at an essentially different view of evolution. It appears to be not a series of accidents, the course of which is determined only by the change of environments during earth history and the resulting struggle for existence, which leads to selection within a chaotic material of mutations . . . but is governed by definite laws, and we believe that the discovery of these laws constitutes one of the most important tasks of the future.' [13] Waddington and Hardy have both rediscovered Goethe's notion of archetypal forms; Helen Spurway concluded from the evidence of homology that the organism has only 'a restricted mutation spectrum' which 'determines its possibilities of evolution'. [14]

  * For an excellent short critical discussion see L.L. Whyte's Internal Factors in Evolution, and W.H. Thorpe's review of the book in Nature, May 14, 1966.

  But what exactly do these authors mean by expressions like 'archetypal selection', 'organic laws co-determining evolution', 'mutation spectrum', or 'moulding influences guiding evolutionary change along certain avenues'? [15] They seem to mean in fact, without saying it in as many words, that given the conditions on our particular planet, the chemistry and temperature of its atmosphere, and the available energies and building materials, life from its inception in the first blob of living slime could only progress in a limited number of directions in a limited number of ways. But this implies that just as the Australian and European wolf were both potentially foreshadowed in the ancestral mouse-like creature, that creature in turn was foreshadowed in the ancestral chordate, and so on back to the ancestral protist, and the first, self-replicating strand of nucleic acid.

  If this conclusion is correct, it sheds some additional light on man's status in this universe. It puts an end to the fantasies of science fiction regarding future forms of life on earth. But it does not mean the opposite either: it emphatically does not mean a rigidly determined universe which unwinds like a mechanical clockwork. It means, to revert to one of the leitmotivs of this book, that the evolution of life is a game played according to fixed rules which limit its possibilities but leave sufficient scope for a limitless number of variations. The rules are inherent in the basic structure of living matter; the variations derive from adaptive strategies.

  In other words, evolution is neither a free-for-all, nor the execution of a rigidly predetermined computer programme. It could be compared to a musical composition whose possibilities are limited by the rules of harmony and the structure of the diatonic scales which, however, permit an inexhaustible number of original creations. Or it could be compared to the game of chess obeying fixed rules but with equally inexhaustible variations. Lastly, the vast number of existing animal species (about one million) and the small number of major classes (about fifty) and of major phyla or divisions (about ten), could be compared with the vast number of works of literature and the small number of basic themes or plots. All works of literature are variations on a limited number of leitmotivs, derived from man's archetypal experiences and conflicts, but adapted each time to a new environment -- the costumes, conventions and language of the period. Not even Shakespeare could invent an original plot. Goethe quoted with approval the Italian dramatist Carlo Gozzi,* according to whom there are only thirty-six tragic situations. Goethe himself thought that there were probably even less; but their exact number is a well-kept secret among writers of fiction. A work of literature is constructed out of thematic holons -- which, like homologue organs, need not even have a common ancestor.

  * Author of Turandot and many other successful works.

  Three times at least, but probably much more often, eyes with lenses have evolved independently in animals as widely different as molluscs, spiders and vertebrates. Most insects have, unlike the spider, compound eyes, but these are merely modifications of the same optical principle: the smooth-curved surface of the camera lens is broken up into a honeycomb of small corneal lenses, each with its own light-sensitive tube. These are the only two basic types of image-forming eyes* throughout the animal kingdom. But again there are countless variations and refinements, from the 'pinhole eye' of the nautilus which functions on the principle of the camera obscura, without lens, through the rudimentary lenses of starfish, up to the precision mechanisms by which various groups of animals achieve accommodation and focussing of the eye on objects of varying distance. Fishes, perhaps because they have more time on their fins, move the whole lens closer to the retina when focussing on distant objects. Mammals, including man, have evolved a more elegant method of focussing by altering the curvature of the lens -- flattening it for close objects, thickening it for distant vision. Predatory birds have developed an even more effective strategy for keeping the prey in focus while sweeping down on it: instead of adjusting the relatively inert lens, they quickly change the curvature of the more flexible cornea. Another essential refinement, colour vision, also evolved independently several times. Lastly, the gradual shifting of the position of the eyes from the side to the front of the head led to binocular vision -- the fusion of the images in each separate eye into a single three-dimensional image in the brain.

  * As distinct from primitive, light-sensitive units which respond to differences in light intensity, but do not provide pattern-vision.

  The purpose of the preceding paragraph was not to praise the glories of vision, but to point to the remarkable achievements of adaptive strategies making the best of the organism's limited possibilities. The limitations are inherent in the physico-chemical structure of living matter as it exists on earth -- and presumably on any planet whose conditions are remotely similar to those on earth. But there is no limit to what an artist can do with Gozzi's meagre list of thirty-six themes.

  XI

  EVOLUTION CTD: PROGRESS BY INITIATIVE

  When you don't know where a road leads, it sure as hell will take you there. Leo Rosten

  Expressions like 'adaptive strategy' or 'exploiting opportunities' imply an active striving towards an optimal realisation of the evolutionary potential.

  In recent years it has become once more scientifically respectable to speak of goal-directedness in ontogeny -- from the canalisation of embryonic development to the purposiveness of instinctive and learned behaviour. But not so in phytogeny. There the official attitude may still be fairly summarised by the following quotation from G.G. Simpson: 'It does seem that the problem [of evolution] is now essentially solved and that the mechanism of adaptation is known. It turns out to be basically materialistic, with no sign of purpose as a working variable in life history, and with any possible Purposer pushed back to the incomprehensible position of First Cause.' And later on: 'Man is the result of a purposeless and materialistic process that did not have him in mind. He was not planned.' [1]

  However, there is no need to engage in philosophical debate over this kind of pronouncement, because it is based on spurious alternatives. According to Simpson, evolution is either 'basically
materialistic' (whatever that means in this context) -- or else there must be a Purposer, a god; man is either the result of a purposeless process or else he must have been 'planned' from the beginning. But the term 'purpose' in its biological context implies neither a Purposer nor a cut-and-dried image of the ultimate goal to be achieved. The predator setting out on its nightly round does not look for a particular rabbit or hare, he looks for a likely prey; the chess-player cannot generally foresee or plan the ultimate mate situation: he uses his skill to take advantage of the opportunities on the board. Purposiveness means goal-directed instead of random activity, flexible strategies instead of rigid mechanisms, and adaptive behaviour -- but on the organism's own terms: it does not 'adapt' to a freezing environment by lowering its body temperature, but by burning up more fuel. In a word, as E.W. Sinnott wrote, purpose is 'the directive activity shown by individual organisms that distinguishes living things from inanimate objects'. [2] Or, to quote the Nobel Laureate H.J. Muller, 'purpose is not imported into nature, and need not be puzzled over as a strange or divine something else that gets inside and makes life go . . . it is simply implicit in the fact of biological organisation, and it is to be studied rather than admired or "explained" '. [3]

  Let me repeat: to talk of 'directiveness', or purpose in this limited sense, in ontogeny, has become respectable once more; but to apply these terms to phylogeny is still considered heretical (or at least in bad taste). But phylogeny is an abstraction, which only acquires a concrete meaning when we realise that 'phylogeny, evolutionary descent, is a sequence of ontogenies', and that 'the course of evolution is through changes in ontogeny'. The quotations in the previous sentence are actually also by Simpson [4], and contain the answer to his own conundrum about the Purposer behind the purpose. The Purposer is each and every individual organism, from the inception of life, which struggled and strove to make the best of its limited opportunities.

  Acting Before Reacting

  When orthodox evolutionists speak of 'adaptations' they mean, as Behaviourists do when they speak of 'responses', an essentially passive process or mechanism, controlled by the environment. This view may be in keeping with their philosophy, but it is certainly not in keeping with the evidence which shows, to quote G.E. Coghill once more, that 'the organism acts on the environment before it reacts to it'. [5] Coghill has demonstrated that in the embryo the motor-nerve tracts become active, and movements make their appearance, before the sensory nerves become functional. And the moment it is hatched or born the creature lashes out at the environment, be it liquid or solid, with cilia, flagellae, or contractile muscle fibre; it crawls, swims, glides, pulsates; it kicks, yells, breathes, feeds on its surroundings for all it is worth. It does not merely adapt to the environment, but constantly adapts the environment to itself -- it eats and drinks its environment, fights and mates with it, burrows and builds in it; it does not merely respond to the environment, but asks questions by exploring it. The 'exploratory drive' is now recognised by the younger generation of animal psychologists to be a primary biological instinct, as basic as the instincts of hunger and sex; it can on occasion be even more powerful than these. Countless experimenters* -- starting with Darwin himself have shown that curiosity, and the 'seeking out of thrills', is an instinctual urge in rats, birds, dolphins, chimpanzees and man; and so is what Behaviourists call 'ludic behaviour' known to ordinary mortals as playfulness.

  * Cf. The Act of Creation, Book Two, Chapter Eight.

  The exploratory drive has a direct bearing on the theory of evolution. This was realised by at least two eminent biologists at the turn of the century -- Baldwin and Lloyd Morgan -- but was promptly and conveniently forgotten. In recent years, however, this so-called 'Baldwin effect' was rediscovered, independently, by Hardy and Waddington. Let me explain what is meant by an amusing example which Hardy gave at a meeting of the Linnaean Society in 1956. A few years earlier, some clever blue-tits had noticed that the bottles which the milkman left at the doorstep contained a puzzling white liquid, and they discovered a way of getting at it by removing the tops of the bottles with their beaks. The liquid proved to be rather delicious. So the birds learned to deal with cardboard tops, and soon also with metal tops. This new skill soon spread, apparently by imitation, 'right through the tit population of Europe' [6]

  Never again will our milk bottles be safe. However, Hardy continued, if the bottles were living organisms -- a species of clams with an odd cylindrical shell; and if the tits continued to feed on them, then after a while only the 'bottles' with thicker caps would survive, and natural selection would produce a species of 'thick-capped bottles' -- but also perhaps a species of tits with 'more specialised, tin-opener-like beaks for dealing with them'. [7]

  The emergence of thick-capped 'bottle' creatures would illustrate the passive, Darwinian type of evolution through the selective pressure of predators in the environment. But the evolution of tits with more efficient beaks is meant to illustrate a quite different type of evolutionary process, based on the initiative of some enterprising individuals in the species. These discover a new method of feeding, a new skill which, spreading by imitation, becomes incorporated into the species' ways of life. The lucky mutation (or re-combination of genes) which produces beaks appropriate to the new skill comes only afterwards, as a kind of genetic endorsement of the discovery. The initial act in the process, the evolutionary pioneer work, so to speak, was done by the tit's exploratory activities, its curiosity which led it to investigate the environment -- and not merely submit to its pressures. We have seen that the famous typewriter of the monkey is controlled by internal selection; now the machine has been further programmed: the monkey merely has to go on trying until he hits a certain pre-specified key.

  The example of the tin-opener beak is of course imaginary, but the conclusions are supported by many observations. Thus one of 'Darwin's finches' on the Galapagos Isles, C. pallidus, pecks holes or crevices into the tree bark, and 'having excavated, it picks up a cactus spine or twig, one or two inches long, and holding it lengthwise in its beak, pokes it up the crack, dropping the twig to seize the insect as it emerges. . . . Sometimes the bird carries a spine or twig about with it, poking it into cracks and crannies as it searches one tree after another. This remarkable habit . . . is one of the few recorded uses of tools in birds' (Hardy [8]).

  According to the orthodox theory, we would have to believe that some random mutation, by modifying the shape of the bird's beak (which, however, is not very different from the beaks of other finches) caused it to develop its ingenious way of hunting insects. And we would also have to believe that it was the same deus ex machina which forced the tit to open milk bottles. Let us rather agree with Hardy that 'the emphasis in the present-day view must be false'; and that the main causative factor of evolutionary progress is not the selective pressure of the environment, but the initiative of the living organism, 'the restless, exploring and perceiving animal that discovers new ways of living, new sources of food, just as the tits have discovered the value of the milk bottles. . . . It is adaptations which are due to the animal's behaviour, to its restless exploration of its surroundings, to its initiative, that distinguish the main diverging lines of evolution; it is these dynamic qualities which led to the different roles of life that open up to a newly emerging group of animals in that phase of their expansion technically known as adaptive radiation -- giving the lines of runners, climbers, burrowets, swimmers, and conquerors of the air.' [9]

  One might call this the 'progress by initiative', or do-it-yourself theory of evolution. It does not do away with chance mutations, but further narrows down the part played by them in the total picture to that of a lucky hit at a pre-set target, which is sooner or later bound to occur. Once it has occurred, the spontaneously acquired habit or skill becomes hereditary, incorporated into the animal's native repertory: it has no longer to be invented or learned, it has become an instinct, endorsed by the gene-complex.* In fact, the range and importance of random mutations h
as been so much whittled down by the various factors mentioned in this and the previous chapter, that the whole Darwin-Lamarck controversy loses much of its importance.

  * In a series of experiments with Drosophila, Waddington has demonstrated that such 'genetic assimilation' (as he called it) of acquired characters becoming hereditary does indeed occur. This does not necessarily mean, however, that Lamarck was right and that the acquired feature (in this case a change in the fly's wing-structure, produced by exposure of the pupae to heat) was the direct cause of the mutation which made it hereditary after a few generations, so that the wing-change occurred even without heat-exposure. It could be that a few mutant flies were already present in the stock, and were then selected for survival on a Darwinian basis; it could also be that the appropriate mutation arose by chance in the process. Waddington leaves the question open whether he had produced an experimental confirmation of Lamarck, or an imitation of Lamarckian inheritance by means of a Darwinian mechanism; he concludes that 'it would be unsafe to consider that the occurrence of directed mutation related to the environment can be ruled out of court a priori', and that 'it seems wisest to keep an open mind on the subject'. [10] That is a far cry from the almost fanatical attitude of the neo-Darwinian citadel.