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Part I

Part II

Part III

Part IV



     

Part IV:  The Fitness of Living Things: Dauermodifications

Chapter 3

Evidence for Dauermodifications Below Man

     THERE IS A built-in stability accompanied by a responsiveness to environmental pressures in all living things plants, animals, and man. This built-in stability guarantees order and therefore a measure of predictability which provides man with the means of controlling the development of things to his own advantage. Responsiveness, on the other hand, fits all these creations of God to their physical world and to one another, to produce a grand harmony. The former is maintained through nuclear inheritance; the latter is achieved through cytoplasmic inheritance.
     It has always been obvious enough, really. Naturalists of an older generation with Christian leanings saw in the fitness of things evidence of God's directive providence at work. Evolutionists later came to attribute this fitness entirely to the operation of chance, rejecting the idea of direct intervention of the Creator. Today it seems that we may once again be in a position, on the basis of hard evidence, to recognize a mechanism by which both stability and adjustment are combined to allow a measure of freedom of variation in form and function without inviting a total breakdown of order.
     The ability of plants to acquire a new character which enhances fitness, and to pass it on to succeeding generations as long as the environment favours it, has been recognized for many years. It was the transient character of this kind of inheritability that defied explanation in conventional Mendelian terms. Yet it is this transient character which seems so necessary to ensure fitness when environmental conditions change. The environment is changed, not merely when a shift in temperature or humidity occurs, but also when a species is forced to migrate into a new habitat due to the pressure of numbers or other competing forms of life. In

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either case, from the point of view of a particular species, the environment has changed and it is essential that the species adjust or become less fit to survive.
     Julian Huxley many years ago remarked upon the fact that plants are able to make this kind of adjustment when they are transplanted. He noted that dandelions whose natural habitat was lowland country changed their size, form, and proportions surprisingly quickly when transplanted to a higher altitude. (20) But the adjustment was transitory, for if these modified plants were then returned to their former habitat, they quite quickly recovered their previous size and form. This phenomenon is common enough in nature. Since the nuclear genes remain constant, the change in either direction has to be attributed to some factor in the cytoplasm.   
     The change in such a case is rapid but not always immediate, and the reversion to type follows the same course. Such a circumstance can only be accounted for on the basis of some kind of inheritableness, since it is progressive and carried over cumulatively. Had mutations of nuclear genes been involved, the effect would be instantaneous rather than occupying several generations. Slow adjustment, even if it occupies only two or three generations, clearly indicates a carry-over effect which demands explanation in terms of some inheritable influence. These dandelion observations ought to have suggested non-nuclear inheritance, but the climate of opinion did not allow such a suggestion or if it was made, it did not gain a serious hearing.
     Now, for many years there has tended to be far greater popular interest in animals than in plants, because the theory of evolution has occupied such a large place in our thinking and comparatively few people connect the theory with plant life. The renewed possibility of the inheritance of acquired characters in animals has begun to excite more interest in recent times, because it could provide an alternative to natural selection as the modus operandi of progressive change. An increasing number of authorities are having second thoughts about the adequacy of the concept of natural selection today, and cytoplasmic inheritance would seem to provide a new and exciting alternative.
     It often happens that when an idea which has hitherto been repudiated begins to receive more favorable attention, a whole wealth of new evidence in its favour is suddenly discovered. It is certain that a number of authorities whose standing in the scientific community is unchallengeable have for some time been questioning the validity of natural selection as an explanation of the fitness of things. Lucien Cuenot in France,

20. HuxIey, Sir Julian, ref.6, pp.36-37.

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Wood Jones and Sir Alister Hardy in England, W. R. Thompson in Canada, and many others have openly challenged it. (21)
     The factors which cause modification tending to greater fitness are observed in animal species at every level of complexity. The pressures which operate to spark these adjustments are of at least three kinds: climatic (which would include environmental temperature, humidity, altitude, wind, etc.); biotic (other living things which exert selective pressures due to predation, crowding, altered breeding habits, etc.); and edaphic (the nature of the rocks and the soil insofar as they influence the types of food available, their varying nutritional character, and the kind of water).
     Sir Cyril Hinshelwood has shown that even such lowly forms as bacteria respond to such pressures. (22) Various kinds of bacteria will "learn" to cope with a new food or poison and will transmit their acquired biochemical wisdom more or less durably (according to the number of cell generations for which the treatment has been applied) to their descendants. We are only too well aware of the fact that various insecticides applied to plants and antibiotics applied to ourselves tend to lose their potency if they are used in one form for too long a period. The organisms under attack develop an immunity (or fitness, from their point of view) without becoming specifically different at a species level. Only by modifying the treatment every so often can they be held in check by reason of the constant upsetting of the mechanism of adjustment whereby they are able to develop immunity. This is clearly a case of dauermodification.
     But it is not merely in these lower forms of life that we observe this phenomenon. We have a number of instances of species of frogs or salamanders which have gradually spread along either side of some natural barrier such as a mountain or a lake and diverged sufficiently as they spread that, when they were again brought into contact at the far end of the barrier, they show themselves to be no longer a naturally interbreeding community. (23) The two populations that demonstrably began as one are now isolates and

21. See Lucien Cuenot, L'evolution biologique: les faits, les uncertitude. Masson, Paris, 1951; F. Wood Jones, Trends of Life, Arnold, London, 1953; Sir Alister Hardy, The Living Stream, Collins, London, 1965; W. R. Thompson, introduction to Centennial edition of Darwin's Origin of Species, Dent, New York, 1959.
22. Sir Cycil Hinshelwood: quoted by Donald Michie, "The Third Stage in Genetics" in A Century of Darwin, ed. S. A. Barnett, Heineman, London, 1958, p. 65.
23. Frogo: Maynard Smith, The Theory of Evolution, Penguin, Harmondsworth, England, 1958, p. 189; and salamanders, Edward Dodoun, A Textbook of Evolution, Saunders, Philadelphia, 1952, pp. 318,321.
 

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continue to be so even though sharing a single habitat again. This separateness may stem from several causes, depending upon the particular route taken by the migrating sub-populations. A different food supply along the way may induce different tastes that become inherited and persist. This in turn may cause a divergence in body odour (24) or size or coloration or mating calls or other changes (25) which are preserved by the two divergent lines even after they come together again in a single habitat. The new tastes may in no way affect the fitness of the individual, and there will therefore be no immediate pressure tending to its reversion.
     It is clear that such divergent subspecies are still genetically a single species, for it can be shown in many cases that they will interbreed in the laboratory. (26) Yet, for what might be called psychological reasons, (27) they no longer do so in nature. It seems likely that in some instances the single habitat shared by both subspecies will tend to draw them together again; but this does not necessarily happen, since their divergent forms may both be very well-suited to their survival so that there is no pressure driving them toward convergence again. The persistence of the divergent forms under these circumstances is clearly an example of dauermodification. T. M. Sonneborn notes that: (28)

     Differing conditions for mating reactivity (temperature, light), once they arise, constitute such effective barriers to interbreeding that different varieties (of protozoa) can and do intimately coexist in the same body of water without losing their integrity. Even when the mating type specificities are only slightly different and interbreeding is possible, the varieties are found to coexist in the same body of water in nature. From these observations, it would seem that even relatively slight changes in mating type specificity could lead to isolation of a new variety.

     The opposite of a divergence is convergence. In this case, two distinct species which cannot be shown to have a common ancestry may increasingly become alike in form and function as a result of sharing similar needs under similar environmental conditions. Some of the evidence of this well-established phenomenon is
 
24. Dodson, Edward, ref. 23, p. 321.
25. Moore, John A., "An Embryologist's View of the Species Concept" in The Species Problem, edited by Ernst Mayr, A.A.A.S., Washington, D.C., 1957, p.329.
26. Dodson, Edward, ref.23, p.318.
27. See New Scientist, 26 February, 1976, p.439 under the heading "Green Toads Sing their Way through Evolution." The frequency and pitch of the toad's mating call is modified by the range of temperature within which the young are matured, and only toads with the appropriate calls any longer attract one another. The community is therefore broken up somewhat by the effects of different temperatures on the young.
28. Sonneborn, T. M., "Breeding Systems, Reproductive Methods, and Species Problem in Protozoa" in The Species Problem, edited by Ernst Mayr, A.A.A.S., Washington, D.C., 1957, p.233.

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examined in a previous volume in this series. (29) Such a mechanism must also involve the principle of dauermodification; otherwise each generation would have to start from scratch and the offspring would be born without the advantages accruing from their parents' experience. The gains would not be cumulative. But we know that such gains are cumulative, because the neonate is usually found to bear in miniature most of the structures which the adult has acquired to its own advantage. For example, a number of animals which live in and out of water display an alignment of nostrils, ears, and eyes that permits them to submerge themselves almost entirely below the water while yet being able to breathe and see and hear what goes on around them. The hippopotamus and the crocodile are among such animals, and their young are similarly equipped.
     F. Wood Jones wrote eloquently about many of these examples of fitness of animals for the kind of lives they live. But unfortunately he attributed it to what can best be described as a kind of mystical goal-seeking drive in all living things directed toward satisfying needs begotten by the circumstances of ecological demands. He commented: (30)

     Exactly how these could be explained on the supposition that structural alterations are due solely to random genetic variations acted on by "natural selection" determining the "survival of the fittest" in a "struggle for existence" is a thing which seems very difficult to conceive.

     It is a principle broadly applied in the history of the development of scientific ideas that a useful theory is not overthrown by the mere citation of contrary evidence, but only by the presentation of a better theory. Natural selection, rightly or wrongly, is a concept which has much to commend it. It appeals to our sense of the obvious, and in terms of human experience the history of man seems to bear it out. Moreover, it can be made rational justification for the powerful among men to exhibit freely some of the worst aspects of human nature.
     But it is not at all certain that animal nature and human nature are the same. What is appropriate in nature may not at all be appropriate in human society, so that neither the reasonableness nor the unreasonableness of the concept of natural selection in human terms has any real bearing on whether it is an appropriate concept to apply in nature. Man is a fallen creature, and his present behaviour makes him unnatural by almost every

29. 0n this, see "Convergence and the Origin of Man," Part III in Evolution or Creation?, vol.4 in The Doorway Papers Series.
30. Jones, F. Wood, ref. 21, p. 84.

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standard of judgment. We do not find the struggle to survive in nature taking the same form as it does in human society. There is no certainty that nature is ruthless in the sense that human society constantly tends
to be.

     The fitness of things in nature is everywhere apparent. The un-fitness of man is also everywhere apparent.
One would suppose that if man is really part and parcel of the web of nature, he will become increasingly fit by the same kind of dauermodifications. There is some evidence that such modifications do indeed improve man's fitness, but there is the disruptive factor of man's fallen nature constantly placing his survival in jeopardy.

     As we shall see in the next chapter, man shares in the web of life to the extent that dauermodifications at least contribute this much to his well-being, namely, that he is better able to obey the command to fill the earth and subdue it. It is dauermodifications that have enabled him successfully to become truly ubiquitous. He can thrive in any climate. It is a remarkable fact that wherever dauermodifications can be demonstrated in man, they seem to serve this purpose above all which may be one more evidence of benevolent design. 

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Copyright © 1988 Evelyn White. All rights reserved

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