Janus: A Summing Up

by Arthur Koestler

  * Cf. Ch. I, 13.

  Now what the Weismann doctrine, or the central dogma, really amounts to is the postulate that a comparable filtering apparatus must protect the hereditary blueprint in the germ-cells against the 'buzzing confusion' of biochemical intrusions which otherwise would play havoc with the continuity and stability of the species. But that does not necessarily exclude the possibility that some very persistent and vital acquisitions, made by generation after generation, may not gradually seep through the filter and become hereditary. There are, at any rate, some classical examples, quoted over and over again in the literature, which seem to cry out for a Lamarckian explanation because Darwinism has none to offer:

  There is, for example, the hoary problem why the skin on the soles of our feet is so much thicker than elsewhere. If the thickening occurred after birth, as a result of pressure and friction, there would be no problem. But the skin of the sole is already thickened in the embryo which has never walked, bare-foot or otherwise. A similar, even more striking phenomenon are the horny callosities on the African warthog's forelimbs, on which the animal leans while feeding; on the knees of camels; and, oddest of all, the two bulbous thickenings on the ostrich's undercarriage, one fore, one aft, on which that ungainly bird squats. All these callosities make their appearance, as the skin on our feet does, in the embryo. They are inherited characteristics. But is it conceivable that these callosities should have evolved by chance mutations just exactly where the animal needed them? Or must we assume that there is a causal, Lamarckian connection between the animal's need to protect these vulnerable spots and the genetic mutation which satisfies that need? [13]

  These examples, and many others which are too technical to be cited here, have been bandied about by Lamarckians ever since the controversy started; and the Darwinians, unable to offer a satisfactory explanation, consistently evaded the issue, or -- on Samuel Butler's phrase -- kept 'ostrichizing' the evidence. A century after Butler, these evasive tactics still prevail.*

  * The interested reader will find a recent example of it in the discussion which took place at the Alpbach Symposium after Professor Waddingtons paper 'The Theory of Evolution Today', when the hoary tale of the ostrich and the warthog was brought up again by the present writer. [16] It was particularly interesting to note that although Waddington was, as we have seen, highly critical of the synthetic theory, he instantly rallied to its defence when it was attacked from outside.

  It is admittedly difficult to see how an acquired callosity could conceivably produce a change in the chromosomes. But, as Waddington himself pointed out in an earlier book [14], 'even if improbable, such processes would not be theoretically inexplicable. It must be for experiment to decide whether they happen or not'. He even produced a 'speculative model' to show a possible way how changes in the activities of body-cells could affect the gene-activities in germ-cells by means of adaptive enzymes. As he wrote, the model was 'intended only to suggest that it may be unsafe to consider that the occurrence of directed non-random mutations related to the environment can be ruled out of court a priori'. [15]

  5

  It has been known for a long time that the 'Weismann barrier' which supposedly isolates the reproductive cells, the carriers of heredity, from the rest of the body, does not apply to plants; nor to lowly animals such as flatworms and hydra, which can regenerate a whole individual, including its reproductive organs, from virtually any segment of their bodies. Ultimately, biologists will have to face the choice of clinging to the dogma of the 'impenetrable wall' protecting the 'unalterable germ-tract' from the rest of the world, and ascribing all evolutionary alterations of it to pure chance -- or admitting that the wall is porous, a system of fine-meshed filters which permits only selected, vital information to penetrate into the inner sanctum of heredity in the germ-cells. Molecular genetics does not tell us -- as yet -- how this is achieved; but it is a new science in constant flux and it does not exclude a priori the possibility of a phylogenetic memory for vital and recurrent experiences encoded in the chromosomes. How else but through some process of phylogenetic learning and memory-formation could the complex inherited skills of building a bird's nest or weaving a spider's web have arisen? The official theory, as we have seen, has no explanation for the genetics of such inherited virtuosity.

  To recapitulate: one can draw an analogy between the filtering apparatus which operates in the nervous system to protect the mind from irrelevant stimuli, and the genetic micro-hierarchy which protects the hereditary endowment against harmful chance mutations, and coordinates the effects of useful ones. We can now extend the analogy and suggest that there is also a Lamarckian micro-hierarchy at work in the process of evolution, which prevents acquired characteristics from interfering with the hereditary blueprint -- except for those select few which respond to some vital need of the species, originating in sustained pressures by the environment over many generations -- like the thickened skin on the soles of the human embryo. We would thus have a quasi-Darwinian micro-hierarchy, mainly responsible for the immensely rich variations on the same level of the evolutionary ladder, and a quasi-Lamarckian micro-hierarchy, mainly responsible for the evolution to higher levels. And there are no doubt still other causative factors at work, beyond our present horizon.

  Only a fool could deny the revolutionary impact of Darwinism on the outlook of the nineteenth century, when -- as one biologist put it, [17] the educated public was faced with the alternative 'for Darwin or against evolution'. But the narrow sectarianism of the neo-Darwinists of our own age is an altogether different matter; and in the not-too-distant future biologists may well wonder what kind of benightedness it was that held their elders in its thrall. This prognosis is shared by some of the critics I have quoted, and perhaps by the majority of the younger generation. It is certainly significant that even in the Introduction, written by an eminent entomologist, to the Everyman Library's Centenary Edition of Darwin's The Origin of Species, we can hear a note of sharp dissent from the orthodox attitude:

  This situation, where scientific men rally to the defence of a doctrine they are unable to define scientifically, much less demonstrate with scientific rigour, attempting to maintain its credit with the public by the suppression of criticism and the elimination of difficulties, is abnormal and undesirable in science. [18]

  It is perhaps significant that in later Everyman editions of The Origin of Species this introduction no longer appears.

  XI

  STRATEGIES AND PURPOSE IN EVOLUTION

  1

  In Chapter I, 10, I mentioned the classic example of the forelimbs of vertebrates which, whether they serve reptiles, birds, whales or man, show the same basic design of bones, muscles, nerves, etc., and are accordingly called homologous organs. The functions of legs, wings and flippers are quite different, yet they all are variations on a single theme -- strategic modifications of a pre-existing structure: the forelimb of the common reptilian ancestor. Once Nature has 'taken out a patent' on a vital organ, she sticks to it, and that organ becomes a stable evolutionary holon. Its basic design seems to be governed by a fixed evolutionary canon; while its adaptation to swimming, walking, or flying is a matter of evolution's flexible strategy.

  This principle is readily applicable to all levels of the evolutionary hierarchy, from the sub-cellular level to the primate brain. The same four chemical bases in the chromosomal nucleic acid -- DNA -- constitute the four-letter alphabet of the genetic codes throughout the animal kingdom; the same 'make' of organelles function in their cells; the same chemical fuel -- ATP -- provides their energy; the same contractile proteins serve the motions of the amoeba and of human muscles. Animals and plants are made of homologous molecules, organelles, and even more complex homologous sub-structures. They are the stable holons in the evolutionary flux, the nodes on the tree of life.

  The theories of evolution discussed in previous pages are primarily concerned with the nature of evolutionary strategies (Darwinian, Lamarckian, etc.) which made
the higher forms of life branch out of the roots at the base of the hierarchy. But dazzled by the prodigious variety of plants and animals, biologists were inclined to pay less attention to the uniformity of those basic units -- reflected in the phenomena of homology -- and the limitations which it imposed on all existing and possible forms of life on this planet. After all, the basic uniformity of the organelles which constitute the living cell is itself derived from the limitations imposed by the basic chemistry of organic matter such as amino-acids, proteins, enzymes. On a higher level,' the genetic micro-hierarchies impose further constraints on hereditary variations. Still further up the 'great central something' regulates -- in ways unknown to us -- the 'harmonious coordination' of genetic changes. Their combined effect is the evolutionary canon, which permits a great amount of variations, but only in limited directions on a limited number of themes. Evolution is not a free-for-all but -- to revert to our formula -- a game with fixed rules and flexible strategies, played over thousands of millennia.

  To illustrate these somewhat abstract considerations, I shall once more use the example of the Australian marsupials, which I used in The Ghost in the Machine.* I called them an enigma wrapped in a puzzle. The enigma is shown by the drawings on p. 208. The puzzle is why evolutionists refuse to see the problems that it poses.

  * The section that follows is a compressed version of The Ghost in the Machine, pp. 143-6.

  (a) Marsupial jerboa and placental jerboa (b) Marsupial flying phalanger and placental flying squirrel. (c) Skull of Tasmanian wolf and skull of placental wolf (after Hardy).

  2

  The class mammalia has two main sub-classes*: marsupials and placentals. They have evolved, independently from each other, from a common ancestry (the now extinct therapsids, or mammal-like reptiles). The marsupial embryo is expelled from the womb in a very immature state of development and is reared in an elastic pouch attached to the mother's belly. A newborn kangaroo is a half-finished job: about an inch long, naked, blind, its hind-legs no more than embryonic buds. One might speculate whether the human infant, more developed but still helpless at birth, would be better off in a maternal pouch; one is also reminded of African or Japanese women carrying their infants strapped to their backs. But whether the marsupial method is better or worse than the placental, the point is that they differ. Pouch and placenta might be called variations in strategy within the general schema of mammalian reproduction.

  * Not counting the nearly extinct egg-laying mammals, such as the duck-billed platypus.

  The two lines split up, as already said, at the very beginning of mammalian evolution some time before Australia became separated from the Asiatic mainland in the late Cretacean. The marsupials (who had branched out from the common ancestral type earlier than the placentals) got into Australia before it was cut off; the placentals did not. So the two lines evolved in complete separation for about a hundred million years. The enigma is why so many animals in the Australian fauna, produced by the independent evolutionary line of the marsupials, look so startlingly like their opposite numbers among placentals. The drawings on p. 208 show on the left side three specimens of marsupials, on the right the corresponding placentals. It is as if two artists who have never met and never shared the same model, had drawn parallel series of almost identical portraits.

  When Australia became an island, the only mammalian immigrants who had managed to get there in time were tiny, mouse-like, pouched animals, perhaps not unlike the still extant yellow-footed pouched mouse, but even more primitive. And yet these archaic creatures, confined to their island continent, branched out and gave rise to pouched versions of our placental moles, ant-eaters, flying squirrels, cats, wolves, lions, and so on -- each like a somewhat clumsy copy of its placental namesake. Why, if evolution were a free-for-all, why did Australia not produce some entirely different species of animals, like the bug-eyed monsters of science fiction? The only moderately unorthodox creation of that isolated island in a hundred million years are the kangaroos and wallabies; the rest of the fauna consists of rather inferior duplicates of more efficient placental types -- variations on a limited number of themes, within the repertory of the evolutionary canon.

  The only explanation for this enigma which the official theory has to offer is summed up in the following quotation from an authoritative textbook:

  Tasmanian [i.e., marsupial] and true wolves are both running predators, preying on other animals of about the same size and habits. Adaptive similarity [i.e., adaptation to similar environments] involves similarity also of structure and function. The mechanism of such evolution is natural selection. [1]

  And G. G. Simpson, the leading Harvard authority on evolution discussing the same problem, concludes that the explanation is 'selection of random mutations'. [2]

  This is question-begging on a truly heroic scale. We are asked to believe that the vague phrase 'preying on animals of approximately the same size and habits' -- which can be applied to hundreds of different species -- provides a sufficient explanation for the emergence of the nearly identical skulls shown on p. 208. Even the evolution of a single species of wolf by random mutation plus selection presents, as we have seen, insurmountable difficulties. To duplicate this process independently on island and mainland would mean squaring a miracle. The puzzle remains why the Darwinians are not puzzled -- or pretend not to be.*

  * Various terms have been invented to describe this phenomenon such as 'convergence', 'parallelism', 'homeoplasy', but these are purely descriptive, without explanatory value.

  3

  The Australian Doppelgängers lend strong support to the hypothesis that there are unitary laws underlying evolutionary diversity, which permit virtually unlimited variations on a limited number of themes. They include, on the lower levels of the hierarchy, macromolecules, organelles and cells which represent evolutionary holons; higher up, homologous organs such as the vertebrate forelimbs, lungs, and gills, not to mention eyes equipped with lenses -- which have evolved, independently from each other, several times in evolutionary lines as far apart as molluscs, spiders and vertebrates. Still higher up we have to include in the list the more or less standardized vertebrate types exemplified by the drawings. The 'more or less' we can ascribe to variations in evolutionary strategy in a changing environment; but their standardization we can only explain by rules built into the genetic micro-hierarchies which confine evolutionary advances to certain main avenues, and filter out the rest.

  This conception of 'archetypal forms' goes back to the German transcendentalists of the eighteenth century, including Goethe (and eventually to Plato); but it was revived by a number of modern evolutionists who toyed with the idea of 'internal selection' without spelling out its profound implications.* Thus Helen Spurway concluded from the universal recurrence of homologous forms that the organism has only 'a restricted mutation spectrum' which 'determines its possibilities of evolution'. [3] Other biologists have talked of 'organic laws co-determining evolution', 'moulding influences guiding evolutionary change along certain avenues' [4]; while Waddington reverted to 'the notion of archetypes . . . the idea, that is, that there are only a certain number of basic patterns which organic form can assume'. [5] What they are implying (without saying it in as many words) is that, given the conditions on our particular planet, its gravity and temperature; the composition of its atmosphere, oceans and soil; the nature of available energies and raw materials, life from its inception in the first blob of living slime could only evolve in a limited number of directions in a limited number of ways. But this in turn implies that just as the basic pattern of the twin wolves was foreshadowed, or present in potentia, in their common ancestry, so the mammal-like reptile creature must have been potentially present in the ancestral chordate -- and so on back to the ancestral protist, and the first self-replicating strand of nucleic acid.

  * See above, Ch. IX, 7. For an excellent short critical discussion see L. L. Whyte's Internal Factors in Evolution and W. H. Thorpe's review of the boo
k in Nature, 14 May, 1966.

  This seems to be the inevitable conclusion derived from the phenomena of homology -- which Sir Alister Hardy has called 'absolutely fundamental to what we are talking about when we speak of evolution'. [6] If this line of argument is correct, it puts an end to the monsters of science fiction as possible forms of life on earth -- or on other planets similar to it. But it does not mean the opposite either: it emphatically does not mean a rigidly predetermined universe which unwinds like a mechanical clockwork. It means -- to revert to one of the leitmotifs of this book -- that the evolution of life is a splendid game played according to fixed rules which limit its possibilities but leave sufficient scope for virtually limitless variations. The rules are inherent in the basic structure of living matter, the variations are derived from flexible strategies which take advantage of the opportunities offered by the former.

  In other words, evolution is neither a free-for-all dependent on chance alone, nor the execution of a rigidly predetermined computer programme. It could be compared to musical composition of the classical type, whose possibilities are limited by the rules of harmony and the structure of the diatonic scales -- which nevertheless permit an inexhaustible number of original creations. Or it could be compared to a game of chess, obeying fixed rules with equally inexhaustible variations. And lastly -- to quote from The Ghost in the Machine --