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Darwin convinced the scientific world that 'descent with modification' (i.e. evolution) was (and still is) a fact. This conviction has remained steady and almost universal; but his proposal about the mechanism involved (natural selection) has been through great vicissitudes. Early in the last century (the 20th), its acceptabilty fell to a low level, mainly owing to the influence of Mendelian genetics. Then in the 1930's a reconciliation took place and the Synthetic Theory (Neo‑Darwinism) became established as the scientific orthodoxy. It is still based on natural selection. However, considerable difficulties remain, stressed particularly by non‑specialists. The biblical doctrine does not stand or fall, however, with the fortunes of the theory.
The plant and animal worlds (especially the latter) exhibit a fantastic amount of variety. Organisms of all sizes, shapes, structures, textures, habits and life‑histories throng the meadows, forests, deserts, mountains, rivers, lakes, caves, shorelines, oceans, and aerial spaces of our marvellous world, and throng them in a richness impossible fully to comprehend. Where did all this diversity come from? It is a natural question, and from quite early days there have been two answers.
On the analogy of things like mineral substances and metals and precious stones, the diverse organisms it has been thought, have always shown the specific distinctnesses that they now show. This is the view commonly called 'Special Creation'. On the other hand, on the analogy of human life, where offspring can differ considerably from their parents and where men and women from distant climes differ even more, it has been thought that in the course of time organisms have diversified in a continuous fashion as one generation succeeded another. This second answer is favoured by the fact that it is based on a closer analogy than the first; it compares living things with living rather than with non‑living. But for centuries it lacked popular appeal because within the time available for personal observation ‑ the mere threescore years and ten ‑ species don't seem to change. Cats remain distinctly cats, and mice mice. It became much more plausible and attractive when the view gained ground that the earth had had a much longer history than had hitherto been thought. Then indeed the stage was set for it to make rapid progress. Today it is without doubt the majority view among scientists. The enormous variety of living things is due to what Darwin called 'descent with modification'. It is this process of slow but vast diversification, generation by generation, over usually long periods that is commonly denoted by the word 'evolution'.
Evolution in this sense is by no means a new idea. It can be traced back in a very rudimentary form even to the Greeks, who seem to have thought of most things. Much later we find men such as Robert Hooke the microscopist (1635‑1703), Goethe the poet and nature philosopher (1749‑1832), and Buffon the encyclopaedist of natural history (1707‑1778) toying with it. Darwin's grandfather Erasmus Darwin (1731‑1802) went further, but suggested no mechanism. It was 'the greatest systematist of his age', the Frenchman Jean Baptiste Lamarck (1744‑1829), who first put forward a detailed theory of how evolution might be accounted for. His theory, now often referred to as 'the inheritance of acquired characters', or of 'the effects of use and disuse', still in fact attracts spasmodic support; indeed Darwin himself invoked it for cases his own theory seemed unable to accommodate. But for the most part it has been discarded. Nevertheless, as the first serious theory of evolutionary mechanism it is worth pausing for a moment to look at it. It proceeds on the following lines.
Consider a blacksmith. He develops his muscles by hard work. Part of the muscular improvement (the theory supposes) passes on by physical inheritance to any children later borne to him, and so the community concerned slowly becomes more muscular.
The trouble with this attractive and easily‑comprehended theory is twofold. First, in spite of intensive search there is no well‑authenticated evidence that characteristics acquired in this way are ever physically transmitted, and there is a great deal of evidence that they are not1. Second, knowledge of the origin, development, minute structure, and preservation in the body of the germ cells reveals no plausible way in which they might be influenced to pass the characteristics on. True, these objections may not be absolutely final: but today they weigh very heavily indeed with the great majority of biologists. Even in his own day Lamarck's theory gained little support; its status remained purely speculative.
Darwin's theory, which came a half‑century later, was very different. Darwin set enormous store on evidence, and held speculation on a tight rein. His theory thus rested on an altogether more secure basis than Lamarck's. It can be illustrated as follows. Among the blacksmith's sons some would chance to have better muscles than others and these would be the ones who tended to follow his trade. In the course of many generations repetition of this pattern would ensure that the blacksmith community became generally more muscular. The result would look the same as that predicted by Lamarck's theory, but the mechanism would be quite different.
Darwin's theory is thus, in its essentials, very simple; it is quite within the power of the layman to appreciate. It starts from two common observations: that offspring vary in unpredictable ways from their parents; and that normally each generation produces more offspring (in lower organisms often vastly more) than can survive and reproduce. This leads to a metaphorical 'struggle for existence' among the progeny of each generation; heritable variations, where beneficial to successful reproduction and survival, dictate the direction in which the population as a whole changes. Two points should be noted especially. First, Darwin regarded the variations involved as random in direction, unrelated that is to any pre‑determined or purposive direction of evolutionary movement. Second, he thought of this evolutionary movement as being directed automatically towards a single result, success in engendering viable offspring. Together, these two points meant that any characteristic of a living organism (lungs to breathe air, warm‑bloodedness, even eyes to see) which could plausibly be regarded as conferring on its possessor an advantage in raising a large healthy family would ipsofacto be explainable as the outcome of an unthinking principle ('natural selection' Darwin called it) acting on variations attributable to chance alone. This devastating conclusion (very different from Lamarck's) worried Darwin himself, and no wonder. It apparently leads inevitably to the conclusion that human life itself has come to be through a process fundamentally meaningless; man must struggle as best he can to give it meaning. But in Darwin's day this verdict was still over the general horizon, and so was not at once overmuch troublesome.
This is not the place to answer the glib and shallow philosophy of 'Evolutionism' to which the undoubted strength of Darwin's biological arguments has lent great support; that is done elsewhere in this essay. Here we are discussing the details of the theory itself. Darwin was a superb naturalist; highly observant, painstaking, industrious, single‑minded, honest, cautious, with a vast capacity for absorbing and weighing his facts. The passage of time has served only to confirm his reputation, and his lasting fame is assured and well‑deserved. He knew there were great gaps in the scientific evidence for his theory, and he was prepared to face them. One of the principal turned on the question of the origin and heritability of the all‑important variations; and as this has had a profound effect on the subsequent vicissitudes of his theory we must briefly consider it.
Imagine a population of glass bottles, each half‑filled with ink of a different depth of colour; this difference would correspond to the variation between living individuals. The population would 'breed' by the contents of random pairs being mixed and the results shared equally between the two members. (We need not bother to suppose the bottles to multiply and divide as well; this would merely overload the analogy without altering the outcome). This mixing and sharing would be continued again and again with the bottles often changing partners. Clearly, if this process was continued long enough the original state of affairs would give way to one in which all colour variation had vanished. This model in fact illustrates what has been called 'blending inheritance', and it represents the view which was held in Darwin's day of the way in which biological traits are passed on from parents to offspring. Obviously, if it were so, variability would always be tending to disappear, and fairly rapidly too. It constituted a great problem for Darwin, for whose theory as we saw, variability is a prime necessity. He never solved it. Ironically it was solved by the work of Gregor Mendel, a contemporary of his, whose experimental results were unnoticed till 1900, eighteen years after Darwin's death. Ironically too, the science of Genetics to which Mendel's work gave rise, for nearly a quarter of a century threw great doubt on Darwin's theory, which in consequence suffered a partial eclipse. However, we must not mislead; loss of faith in Darwin's personal theory did not mean loss of faith in evolution. That was never the case; confounding the two is a frequent mistake. Since Darwin convinced the world of science that evolution had really taken place, the idea of evolution has always been in the ascendant. It still is, however much biologists (and other scientists) wavered in their convictions for many years as to how it had been brought about.
Mendel's theory, as it is now understood, can be illustrated by slightly modifying our analogy. Imagine the bottles to be half‑filled not with a liquid, but with glass marbles. In some bottles all marbles are colourless; in many others one, or two, of the marbles are black. The bottles are set 'breeding' continuously as before. However long they continue, uniformity of 'colour' throughout the population will never result. At the end. the range in colour will be the same as it was at the start 2. The reason for this is twofold. First, inheritance is here particulate, the marbles are passed on as wholes. Second, owing to the behaviour of the chromosome mechanism (unknown in Darwin's and Mendel's day), the 'genes' (as the marbles can now be called) are always paired, one of each pair coming from one parent and its corresponding partner from the other. The results of Mendel's experiments fitted very well into this scheme, but Darwin's continuous variation didn't. Where did it come in then? It was a long time before the problem was solved, but to cut a long story short it became clear that Mendel had been fortunate in picking rather simple cases for experiment; the difference between his tall and short peas for instance lay in a single gene 3. But characters are often the outcome of the joint interaction of many genes. If colour in the marbles had involved many different sorts of 'black' gene (black 1, black 2, black 3 and so on), all being independent from one another but having additive and 'look‑alike' effects on their host plant, its resultant 'colour' could clearly have varied fairly continuously, even becoming nearly uniform in time.
The establishment of Mendelian genetics on a firm experimental basis (which Darwin's theory in his own hands could hardly have aspired to), led to a long period in which Darwin's ideas were in partial eclipse, and many great names can be cited against them. Evolutionthey still believed, but not Darwinism. It was not until the second quarter of the last‑century (the 1900's) that the apparent antipathy between Darwinism and Mendelian genetics began to be resolved 3. The realization that made this possible was that genes worked together in large numbers; it was the whole 'gene complex' that must be considered, not individual genes acting alone. If a character (like size) is under the control not of one gene only but of a hundred, then clearly heritable variation could be much more continuous. However, things are in general much more complex even than this. The organism is rather like a social gathering, where the behaviour of any one guest may be markedly dependent on who the others are. On one occasion a guest may have a lot to say for himself; on another he may be quite subdued. This realization, as has been remarked, began to transform the impact of Mendelian genetics on Darwin's theory; and somewhere in the 1930's a new Synthetic Theory of Evolution, often called neo‑Darwinism, began to find general acceptance. The outstanding mathematical work of the 'population geneticists', Fisher, Haldane and Sewall Wright, had a great deal to do with this, and today neo‑Darwinism is still the prevailing scientific orthodoxy. What neo‑Darwinism supposes is that natural selection operates on heritable variations due to sudden discontinuous 'mutations' in the genetic material, all intricately interacting within the whole genetic complex or 'genome'; the result understandably sometimes simulates Darwin's continuous variation. The synthetic theory is therefore still justly known by Darwin's name. His key idea (natural selection), and Mendel's, it is believed, have proved not rivals, but partners 4.
Does this mean that the wider scientific fraternity is now satisfied that the answer has been found to the riddle of how evolution has occurred? Before I attempt to answer this question I must disclaim any specialist knowledge. I am a biologist, but I cannot speak as an expert here. However, I will attempt an assessment. It is probably true to say that those whose work is most intimately concerned with the subject ‑ the population geneticists, the evolutionary systematists and so on – do feel satisfied, though they would insist that we have a long way still to go. Other thoughtful biologists and those from disciplines further afield may not be so sure. Many readers will know, for instance, of the sarcastic comments of the cosmologist Sir Fred Hoyle, who uses arguments based on probability but of questionable validity (as indeed many of such arguments are)5.
This rather unsatisfactory position arises like this. Evolution concerns what happened in pre‑history; consequently evolutionary theory (grappling with aeons of time) can never be tested in the way in which theories of brain function or quantum mechanics can. At the end of the day we inevitably find ourselves up against the question, "Do I find this credible?" Consider as an illustration the well‑known case of the origin of the vertebrate eye. Can it really be believed that such an amazing organ, with so many complexly interacting structures and functions working together, has resulted from nothing more than chance variations acted on by the unthinking process of natural selection? Darwin himself, as is well known, stumbled at this suggestion, though he came down finally with the answer "Yes". In theory, as Richard Dawkins well argues, all stages from nothing to the perfect eye can be thought of as worthwhile. He then goes on to quote Fisher 6, that as a mutation becomes smaller in its effects, so the likelihood of its being a beneficial one rises towards 50%; so where's the problem? But as Donald MacKay pointed out, as the mutation becomes smaller and its probability of being a 'good' one rises towards this 50%, so its benefit falls towards zero! An additional and important consideration is that the very same mutation that benefits one function (enlarging say the skin flaps of flying squirrels) may detract from another (weakening its climbing muscles). Dawkins' argument tends to forget these things. But all such suggestions can hardly be proved; they will probably remain to the end of time either credible or incredible. It is pertinent to remark that what one finds oneself able to believe (or forced to disbelieve) is dependent not only on scientific arguments but also on one's basic presuppositions. Are scientific categories for instance ultimate, or are there others behind and beyond them? Is there, or is there not, a Creator? And if there is, how far can naturalism (that is, the common methodology of science) be pursued before it comes up against a final limit? These are not insignificant questions, though they are often treated as such by the intellectually‑blinkered secularist.
The reader who is interested in other difficulties of neo‑Darwinism might consult THE GREAT EVOLUTION MYSTERY by G Rattray Taylor 7. I mention this because the author writes as a convinced secularist, but he does knowledgeably and systematically catalogue the serious problems facing the current orthodoxy.
Of the problems which can be appreciated most easily, that of 'missing links' comes first. Suppose an artist had produced a detailed series of drawings illustrating evolutionary change as Darwin envisaged it, serializing the gradual transformation of a 'fish' into a 'reptile'. The drawings would be meant to represent many possible stages through which the living stream of vertebrate life has smoothly passed. The question is this: why can't we find a series of fossils which, arranged in temporal order, answers to a similar continuous sequence? This is the problem of the missing links. Where are they all? There are cases where the fossil record does yield the sort of thing we want (such as the oysters), and there are cases where two large distinct groups appear to be connected by a more‑or‑less isolated intermediate form (such as the reptiles and the birds with Archaeopteryx between); but these are not very substantial offerings in the face of what the theory seems to demand. The difficulty is by no means a slight one; the usual reply has been that the fossil record is very incomplete. It provoked the eminent palaeontologist and geneticist Richard Goldschmidt to propose his theory of 'hopeful monsters' 8 ‑ that many evolutionary changes (such as the acquisition of hair in mammals, or feathers in birds) took place not in gradual stages by natural selection, but in one fell swoop, by a sort of gigantic genetic leap. More recently has come the theory of 'punctuated equilibria' associated with the names of Niles Eldredge and Stephen J Gould. They suppose that a very common occurrence has been a long period of relative stability (with abundance of fossils) followed by a brief period of considerable and rapid change (leaving few), and followed again by a period of stability. Eldredge's attention had been attracted by a form of trilobite (a sort of giant woodlouse) abundant in a fossil bed suddenly dying out and being replaced by a distinctly different form. Causes for such phenomena have certainly been suggested (the isolation of small populations, or some great catastrophe). But the inevitable credibility problem remains; nothing in the past can be experimentally re‑enacted. 'Punctuated equilibria' appears to many (including Dawkins himself) as an unnecessary suggestion; it is, however, being warmly defended.
Several major themes remain to be briefly mentioned. It may surprise the reader to know that no generally accepted explanation has yet been proposed for the phenomenon of sexuality in plants and animals. Why is this phenomenon so widespread? It is not logically necessary for procreation, in fact many organisms get on quite well without it. To secular biologists, its prominence remains a considerable mystery 9. Another debatable point amongst Darwinists concerns what most people would regard as obvious: is 'progress' a right evaluation of what has taken place during evolution? Dawkins, Atkins and Dennett are quite tongue‑tied on this too 10; the Bible is clear and outspoken. Finally, at the base of the edifice of orthodox theory lie the immense difficulties surrounding the origin of the genetic mechanism itself. For instance. the DNA 'tape' containing the genetic instructions requires enzymatic proteins to fabricate it, but the enzymatic proteins themselves require the DNA tape to fabricate them. How does the whole system get off the ground? Further, how and when did the astonishing mechanisms for its near‑impeccable operation develop, complete with the highly significant 'crossing‑over' between the two strands? There may well be answers to these points coming within the competence of naturalistic science to unravel; but I am not quite so sure about the final one, how the language or 'code' in terms of which the DNA delivers its message, came to be what it is. The biblical theist certainly has to beware of invoking a mistaken 'God of the gaps' solution here and elsewhere; its god is too small! The Bible warns him too that ultimately his mind has final limitations (Deut.29.29) and he must accept them. The secularist also has to beware of giving equally trivial answers, the sort which compel him to lay the matter finally at the feet of the goddess Chance. How does she answer? Easy; by the simple principle of self‑reference. Non‑existent spacetime generates its own dust (up till then also non‑existent), and this dust then returns the compliment! After that everything is simplicity itself. If the reader wishes to follow that up he may do so in two references 11. But he had better get in touch with Douglas Adams first; he will need the latter's 'electric monk' for success; "he was purpose‑built to do your believing for you, and very successful at it"12. For myself, I am fully persuaded that at some point (I am far from prepared to say exactly where), naturalistic science, dependent at rock bottom on the evidence of the physical senses, finally loses its ability to offer any further coherent explanation 13 on such matters of unrecorded history.The positive side of evolution
It would not be fair to leave this account of 'Darwinism Today' without some comments from the opposite angle. My opponents, while intending to be admirers of Darwin are in fact possibly doing his cause a great disservice. The flimsy suggestions Prof Atkins has offered for the very beginning 11, and Dawkins' unattractive attitude to those who differ from him will hardly persuade most readers that they are sound and reasonable advocates. So what are the solid grounds for believing in Darwin's Descent with modification?
The first is the fossil record. This bears irrefutable witness to the fact that a vast range of animal and plant species have existed on the earth of which no living members remain today. Indeed, so great is the variety of fossil forms now known that it is estimated that extinct species outnumber living ones by one hundred to one 14. But the record can hardly be read as indicating an incredibly rich variety at the beginning (the opening week?) of which all but one in a hundred have now died out. It seems much more reasonable to suppose that as some forms died out others replaced them, the number of living forms possibly continuously rising. The theory of evolution makes sense of this; the idea of 'special creation' (as earlier defined)15 doesn't ‑ at least, not without biblically‑unwarranted sophistication.
Another very striking fact about the living world is its unity. This is true in at least two ways. Biochemically, a vast range of molecular groupings and enzymatic systems turns up repeatedly 16; again, genetically the significance of DNA and the genetic code are universal. No doubt a case could be made out for these things being highly desirable (and so explicable) on the basis of 'special creation'; but I must confess they seem to me far more naturally meaningful and comprehensible if living things are related by an evolutionary (but not necessarily a Darwinian) mechanism. Perhaps we could add a third way in which the living world is a unity: systematically. For living things can to a large extent be classified in a hierarchical fashion: species, genera, families, orders and so on. It seems an entirely natural impression that all species of rose say, or of iris, must be related, and not just in the sense that their flowers have the same form, but in the sense (being living things) that their genealogies must join up somewhere as we trace them back. And if genera thus comprise species from a common origin, why shouldn't the same argument hold for genera, families, orders, . . . and where does one stop? And that of course means evolution (though again, not necessarily Darwinian).Conclusion
It is time this chapter concluded. It has attempted to give a fair resumé of the present standing of the currently orthodox theory of evolution, Neo‑Darwinism. It has possibly left perplexity, even uneasiness. Evolution at one moment it may seem to say, is utterly indisputable; it stares you in the face. But the next moment there are some doubts. Why aren't all the great animal and plant phyla seen to join up more obviously in the fossil record? The gaps seem sometimes to be enormous. We find enough significant links (such as Archaeopteryx) to hold out great promise, but hardly enough to satisfy. It is all devilishly teasing! Darwin himself once remarked that the origin of the angiosperms or flowering plants (the reader must forgive my being a botanist) was "an intolerable mystery". It still is, as are many other comparable origins; and that after well over a century and a half of intensive search and research. Then as to mechanism; there seems no acceptable alternative to the synthetic theory. But while the specialists regard it as entirely competent to cope, many highly qualified non‑specialists have the gravest of doubts. At the lower end of the evolutionary ladder, where the debate concerns the origin of life from non‑living matter, there is no consensus. Moreover, the determination to push naturalism to the extreme limit is so great (here as in cosmology) that no end of the controversy with secularism can be seen through the latter's sheer exhaustion. However, the objective of this essay has never been to dislodge Darwinism, not even the dogma of the spontaneous generation of life. It has been to commend the biblical doctrine of creation as still "worthy of full acceptation". That doctrine I have attempted to show, does not stand or fall with the fortunes of evolutionary theory; it completely transcends it. It stands on the authority of the Bible as confirmed by Jesus Christ. The uncertainties and vicissitudes of evolutionary theory are of no more significance to it than are those of gravitational theory. Once we have grasped what the Bible implies by the Sovereignty of God17 over even what men think of as 'randomness' or the 'Dominion of Chance', the intellectual problem (at least) is gone. Only the desire (hardly confessed perhaps even to themselves) to escape from God (Rom.1.28 NIV) stands in the way of men and women receiving the Bible as "God's Word written"18, and ordering their lives by it.NOTES
1 For instance, the failure of the 'foot‑binding' of Chinese women to influence subsequent generations.
2 That is, if there was some device present to limit the number of any particular type found together to two. In the living cell this is the chromosome mechanism; it is omitted here for simplicity.
3 The phenomenon of 'dominance' complicated matters here very slightly.
4 For a popular fair‑minded review see Alan Howard CREATION AND EVOLUTION (Triangle, 1985). A more technical account is J.Maynard Smith THE THEORY OF EVOLUTION (Penguin, 3rd edn. 1975). GOD AND EVOLUTION R J Berry, (Hodder and Stoughton, 1988) seeks to reconcile Genesis and neo‑Darwinism.
5 GOD OF CHANCE, D J Bartholomew (London, SCM Press, 1984)
6 See THE BLIND WATCHMAKER p 231f
7 Secker and Warburg, 1983. Rattray Taylor was a convinced secularist.
8 THE MATERIAL BASIS OF EVOLUTION, Richard Goldschmidt (Yale Univ. Press, 1940)
9 THE SELFISH GENE, pp.43,274. For a longer discussion see THE THEORY OF EVOLUTION, John Maynard Smith, 1975, 3rd edn., Penguin.
10 THE BLIND WATCHMAKER, pp.262f,268. The Bible says something positive on both points: see Gen.2.18 for sexuality and 1.26 for progress.
11 THE CREATION, P.Atkins pp.99,111f,119; CREATION REVISITED p.vii (What amazing dreams!)
12 Dawkins in THE SELFISH GENE, p.330. He is quoting Douglas Adams, DIRK GENTLY'S HOLISTIC DETECTIVE AGENCY, Pan Bks, London. 1988
13 See possibly the phenomenon of language (Gen.1.28; 11.7); also the death of the firstborn (Exod.11); and supremely, the Resurrection of Jesus Christ (1Cor.15.1‑8).
14 Rattray Taylor op. cit. p.86
15 Chap. VI
16 The same twenty or so amino‑acids form the common constituents of proteins from all organisms; they are all in the same (laevo‑) form; ATP is a universal energy metabolite: chlorophyll is related to the haeme of blood; and so on. Not surprisingly, cell ultrastructure shows many universal features too.
17 The references in the Bible are too many to quote, but see Eph.1.11; and Chap.II.
18 Article 20 of the "39 Articles" of the Book of Common Prayer