The Darwinians have coined the words pseudo-teleology and teleonomy to refer to final causes whose existence at the same time they deny. They say that the appearances are deceptive, that the constituents of life are all products of chance; and that what we take for finality* is nothing but the ordering of haphazard building blocks by natural selection . . . As a matter of fact, the terms pseudo-teleology and teleonomy pay tribute to finality, as hypocrisy pays homage to virtue . . . [55] * 'Finality': principle of final cause, i.e., purpose viewed as operative in the universe. 'Teleology': view that developments are due to the purpose or design served by them (Concise Oxford Dictionary).
Yet Jacques Monod was not a hypocrite. He was brilliant in his specialized field, but disarmingly naive concerning the theoretical implications of it -- what his compatriots call a 'terrible generalisateur'. This, of course, applies to many of his eminent colleagues in the neo-Darwinian establishment. Guided -- perhaps unconsciously -- by the maxim that a bad theory is better than no theory, they are unable or unwilling to realize that the citadel they are defending lies in ruins.
X
LAMARCK REVISITED
1
Genetic atomism is dead. As dead as the atomism of nineteenth-century physics, which regarded atoms as hard little indivisible marbles. The living organism is not a mosaic, where each bit is governed by a separate gene, and evolution does not proceed by replacing individual bits in a haphazard fashion until, lo and behold, the image of a fish is replaced by that of an amphibian. In The Ghost in the Machine I compared the present crisis in evolutionary theory with the falling apart of medieval cosmology. The pages that follow carry the argument one step further.
2
In his Evolution Old and New, published in 1879, Samuel Butler wrote: 'Lamarck has been so systematically laughed at that it amounts to little less than philosophical suicide for anyone to stand up on his behalf.' Nearly half a century later, Paul Kammerer, the most brilliant Lamarckian of his time, was driven into bodily suicide by the laughter and hostility of his fellow biologists.* At the time of writing, another fifty years later, Lamarckism is still an emotional minefield, which academics may enter only at the risk of having their reputations and careers blown to bits.**
* The Case of the Midwife Toad is an account of his life and the controversy surrounding his work. ** In France there is more tolerance in this respect; after all, Lamarck was French, Darwin British.
The explosive core of the argument was -- and still is -- a seemingly innocuous postulate: 'the inheritance of acquired characteristics', which Lamarck formulated at the beginning of the nineteenth century, in his Philosophie Zoologique. The term 'acquired characteristics' refers to improvements in physique, skills, or ways of life, which individuals acquire through their efforts to cope with the environment and to exploit the opportunities it offers; in other words, progressive changes which correspond to the vital needs of the species and which -- here's the rub -- are transmitted, according to Lamarck, from parents to offspring through the channels of heredity. Successive generations would thus benefit from the struggles and exertions of their forebears by direct bodily inheritance (and not only indirectly through imitative learning from their elders).
Some early Lamarckians actually believed that a blacksmith's son would be born with stronger than average biceps, without having to develop them by repeating his father's efforts all over again, and that a concert pianist's offspring would inherit some of his father's acquired skill. But neo-Lamarckians abandoned these naive views a long time ago; they hold that only biologically vital characteristics which are acquired in response to intense and persistent pressures of the environment over many generations become eventually hereditary, that is, incorporated into the gene-complex. In spite of this qualification, the essence of Lamarckism is the belief that the efforts of the parents are not entirely wasted, that some of the benefits derived from their experiences and labours are transmitted to their offspring, and that this is the principal active cause of evolution 'from amoeba to man'.
Thus in the Lamarckian view, evolution is a cumulative process, the outcome of the purposeful striving of living organisms (not very different from Monod's teleonomy), whereas in the neo-Darwinian view evolution is an accidental process, in the course of which the parents can transmit through the channels of heredity only what they have inherited themselves, plus some (mostly harmful) aberrations in the genetic material. Thus from the point of view of the offspring, the struggles and achievements of their ancestors were wasted, and amounted, in the words of Ecclesiastes, to mere 'vanity - and chasing the wind'. The two contrasting attitudes can be summed up by two quotations: the first is from Kammerer, the Lamarckian:
It is not merciless selection that shapes and perfects the machinery of life; it is not the desperate struggle for survival alone which governs the world, but rather out of its own strength everything that has been created strives upwards towards light and the joy of life, burying only that which is useless in the graveyard of selection. [1]
The second quotation is from Simpson of Harvard, an eminent neo-Darwinian:
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 . . . Man is the result of a purposeless and materialistic process . . . [2]
It is not surprising that such diametrically opposed attitudes became fraught with emotion, comparable to the theological disputes of the past. As Sir J. A. Thomson wrote in 1908:
The question as to the transmissibility of characters acquired during life by the body of the parent . . . is much more than a technical problem for biologists. Our decision in regard to it affects not only our whole theory of organic evolution, but even our every-day conduct. The question should be of interest to the parent, the physician, the teacher, the moralist, and the social reformer -- in short, to us all. [3]
It is not only of historical interest that Darwin himself remained all his life half a Darwinist and half a Lamarckist. In his The Variation of Animals and Plants under Domestication, published in 1868, and in his notebooks, he gave a whole series of spurious examples of the inheritance of acquired characteristics: 'the cat had its tail cut off at Shrewsbury, and its kittens had all short tails', or 'a man losing part of his little finger and all his sons being born with deformed little fingers', and many similar old wives' tales in which he earnestly believed; and in 1875, towards the end of his life, he wrote to Galton that each year he found himself more compelled to revert to the inheritance of acquired characteristics because chance variations and natural selection alone were apparently insufficient to explain the phenomena of evolution. The examples he quoted were no doubt apocryphal, but they prove that if Lamarckism was 'a disreputable ancient superstition' (as Professor Darlington called it), Darwin himself shared it. [4] And so did Herbert Spencer, the great apostle of Darwinism, who wrote in his Principles of Biology (1893):
Close contemplation of the facts impresses me more strongly than ever with the two alternatives -- either there has been inheritance of acquired characters, or there has been no evolution. [Italics in the original. [5]
Thus in that early period it was possible, and even usual among evolutionists, to be both a Lamarckian and a Darwinian at the same time. With the advent of neo-Darwinism this peaceful coexistence came to an end, Lamarck was excommunicated, and the eclecticism of the early evolutionists was transformed into an attitude of sectarian intolerance.
The ostensible cause of the schism was a doctrine, propounded in 1885, three years after Darwin's death, by the German zoologist August Weismann -- the doctrine of the 'continuity and unalterability of the germ-plasm'. Weismann's 'germ-plasm' is the carrier of the hereditary endowment (today called the 'genetic blueprint'); it is located in the sex-cells -- sperm and ovum -- which are set aside at an early stage in the development of the embryo, isolated from the soma-cells that will give rise to
the rest of the body; and is transmitted to the next generation along the 'continuous germ-tract', unaltered and unaffected by anything that happened to the transient individuals which harboured the immortal plasm in their ovaries and testicles. The doctrine that no 'acquired characteristic' can penetrate the barrier protecting the germ-plasm and alter the hereditary endowment became an integral part of the neo-Darwinist creed, and still is -- brought up to date in Crick and Watson's provocatively named 'central dogma'. It tells us that the DNA chains of heredity in the chromosomes are kept in splendid isolation from the rest of the body, that they are potentially immortal molecular structures, protected from the hazards of life, and passed on, unaltered, from generation to generation, ad infinitum, unless some nasty radiation intervenes. It is a depressing doctrine, whether true or not. The indications are that it is not.
Neo-Darwinism did indeed carry the nineteenth-century brand of materialism to its extreme limits by proclaiming the evolution of man to be the result of 'a purposeless materialistic process', ruled by 'blind chance'. And therein, precisely, lay its perverse philosophical attraction -- in its uncompromising rejection of any trace of purpose in the manifestations of life; in its grim determination to reduce ethical values and mental phenomena to the elementary laws of physics; and to brand those aspects of biology which cannot be thus reduced, as unworthy of scientific attention.
How this metaphysical bias influenced and distorted scientific methodology is illustrated by a hilarious episode rarely mentioned in the textbooks. In order to prove his doctrine that the 'germ-plasm' remained unaffected by acquired characteristics, Weismann amputated the tails of twenty-two successive generations of rats to see whether eventually a tail-less rat would be born. No such rat was born, so Lamarck was refuted. However, as one unrepentant Lamarckian remarked, Weismann might as well have studied the inheritance of a wooden leg. For Lamarck's thesis was that only such acquired characteristics become inheritable which an animal develops as a result of its natural, vital needs -- and having its tail chopped off can hardly be called a vital need of the rat.
3
Neither Weismann, nor anybody else, has been able to disprove Lamarckian inheritance, because of the inherent difficulty of proving a negative: the Lamarckians could always argue, with perfect justification, that evolution works on an incomparably larger time-scale than a research team, however patient. This was admitted even by staunch Darwinians, such as J. B. S. Haldane:
It must be remembered that however many experiments fail, it is always possible that the effects of acquired characters may be impressed on a species at a rate not susceptible to experimental verification, yet rapid enough to be of importance in geological time.
It is rather amusing to note that Sir Julian Huxley, as we have seen, used exactly the same argument in defence of Darwinian inheritance against its critics: the '"hoary objection" of the improbability of an eye or a hand or a brain being evolved by blind chance has "lost its force" because natural selection is "operating over the stretches of geological time".' [7]
While it was thus impossible to disprove either the Darwinian or the Lamarckian theory by experiment, it turned out to be equally impossible to prove either of them. On the Lamarckian side, the great Pavlov in Leningrad and MacDougall at Harvard attempted to show that the results of conditioning in mice and rats were inherited -- and failed to do so.* On the other hand, the patient labours of the Darwinian geneticists on thousands of generations of Drosophila have also failed to produce any evolutionary improvement. As far as the direct experimental evidence is concerned, the two sides might have called it quits.
* Perhaps closest to such proof came Karnmerer's controversial experiments, described in The Case of the Midwife Toad and J. McConnell's experiments on Planaria. [8]
If the neo-Darwinians nevertheless carried the day -- for the time being -- the reason was, apart from metaphysical bias, that they were apparently able to offer 'modern', scientific explanations of some aspects of the evolutionary process, which the Lamarckians were unable to do. The discovery of Mendel's laws, the statistical approach to genetics, and lastly the 'breaking of the genetic code', each looked at first like an added confirmation of Darwin's prophetic foresight (forgetting his own lapses into Lamarckism). The mechanism of evolution which he had proposed may have been crude, in need of modifications and refinements; but the Lamarckians could not offer any mechanism at all in keeping with modern biochemistry. Random mutations in the chromosomes, triggered by radioactivity or noxious chemicals, were prima facie scientifically acceptable as a base for natural selection. But no acceptable hypothesis was forthcoming to explain how an acquired bodily or mental feature could alter the 'genetic blueprint', contained in the micro-structure of the chromosomes. So once more the principle prevailed that a bad theory is better than no theory, and Lamarckism acquired the stigma of a 'disreputable superstition' because it postulated a principle in nature without being able to offer a mechanism, in terms of contemporary science, to account for it.
This situation, however, has many precedents in the history of science. When Kepler suggested that the tides were caused by the attraction of the moon, even Galileo dismissed the idea as an 'occult fancy' because there was no conceivable mechanism which could explain action-at-a-distance. Later on, some of Newton's most eminent contemporaries rejected universal gravity because it meant, in his own words, 'grappling with ghost fingers at distant objects' and thus contradicted the laws of mechanics. Mutatis mutandum, Lamarckism was rejected because the proposition that the experiences acquired by the living organism could influence the structure of its hereditary chromosomes contradicted the laws of genetics summed up in the 'central dogma'.
In actual fact the central dogma succumbed in less than twenty years after its proclamation under the weight of rapidly accumulating new evidence. On 25 June 1970, the New Scientist (which does not go in for sensational headlines) announced: 'Biology's Central Dogma Turned Topsy-Turvy' and The Times Science Report followed suit: 'Big Reverse for Dogma of Biology'. [9] The experimental work, which overturned the central dogma (and which six years later was rewarded by a Nobel Prize)* is too technical to be detailed here; suffice it to say that it established beyond dispute that in certain bacteria the 'hereditary blueprint' can be altered by the incorporation of agents of external origin (viruses), which may have harmful or benign effects. [10] Or, as Grassé summed it up:
These results demonstrate that there exists a molecular mechanism which, in certain circumstances, supplies information from outside to the organism and inserts this information into the organism's genetic code. This is of immense importance to evolutionists." * Shared by Temin, Baltimore and Dulbecco
It is indeed. This is why I called molecular genetics a Trojan Horse inside the citadel.
It would, of course, be silly to jump to the conclusion that because viruses can produce hereditary changes in a cell, therefore continued piano practice by the parents will make them beget musical prodigies. Nevertheless, the discoveries of molecular genetics in the course of the last decade have finally demolished Weismann's doctrine of the 'unalterability of the germ-tract' and modified its modern version, the 'central dogma'. Taken in conjunction with the criticisms discussed earlier on, they may signal the beginning of the end of neo-Darwinism as represented in contemporary textbooks. Darwinian selection no doubt plays a part in the evolutionary process, but only a subordinate part (comparable to the action of the selective weedkiller) and there is a growing realization that there must be other principles and forces at work on the vast canvas of evolutionary phenomena. In other words, the evidence indicates that evolution is the combined result of a whole range of causative factors -- some known, others dimly guessed, yet others so far completely unknown.
4
In The Case of the Midwife Toad I suggested that within that wide range of causative factors a 'modest niche might be found for a kind of modified "mini-Lamarckism" as an explanation for some limited and rare evolutionary phenomena
'. [12] In the light of recent developments I am no longer sure that the niche must be so modest, and the phenomena so rare. It would of course be absurd to revert to the naive version of Lamarckism which Darwin himself embraced. As said before, Lamarckism only makes sense if the inheritability of acquired characteristics is confined to such bodily features and skills which organisms acquire in response to persistent pressures and challenges of the environment over many generations.
This limitation is essential, and the reasons for it can be explained by a simple analogy. Our sense organs for sight and hearing act like narrow slits or filters which admit only a very limited frequency range of electro-magnetic and sound waves. But even this reduced input is too much for us to cope with. Our minds would cease to function if we bad to attend to each of the millions of stimuli which -- in William James's classic phrase -- constantly bombard our receptor organs in a 'blooming, buzzing confusion'. Thus the nervous system and the brain itself function as a multilevelled hierarchy of filtering and classifying devices, which eliminate a large proportion of the input as irrelevant 'noise', and assemble the relevant information into coherent patterns before it is presented to consciousness.* A typical example of this filtering-and-synthesizing process is what psychologists call the 'cocktail-party phenomenon' -- our remarkable ability to isolate and attend to a single voice from the medley of sounds impinging on the ear-drum.
Janus: A Summing Up Page 22