_ CHAPTER VII. (Intercalated) Mr. Spencer's "The Factors of Organic Evolution"
Since the foregoing and several of the succeeding chapters were written, Mr. Herbert Spencer has made his position at once more clear and more widely understood by his articles "The Factors of Organic Evolution" which appeared in the Nineteenth Century for April and May, 1886. The present appears the fittest place in which to intercalate remarks concerning them.
Mr. Spencer asks whether those are right who regard Mr. Charles Darwin's theory of natural selection as by itself sufficient to account for organic evolution.
"On critically examining the evidence" (modern writers never examine evidence, they always "critically," or "carefully," or "patiently," examine it), he writes, we shall find reason to think that it by no means explains all that has to be explained. Omitting for the present any consideration of a factor which may be considered primordial, it may be contended that one of the factors alleged by Erasmus Darwin and Lamarck must be recognised as a co-operator. Unless that increase of a part resulting from extra activity, and that decrease of it resulting from inactivity, are transmissible to descendants, we are without a key to many phenomena of organic evolution. UTTERLY INADEQUATE TO EXPLAIN THE MAJOR PART OF THE FACTS AS IS THE HYPOTHESIS OF THE INHERITANCE OF FUNCTIONALLY PRODUCED MODIFICATIONS, yet there is a minor part of the facts very extensive though less, which must be ascribed to this cause." (Italics mine.)
Mr. Spencer does not here say expressly that Erasmus Darwin and Lamarck considered inheritance of functionally produced modifications to be the sole explanation of the facts of organic life; modern writers on evolution for the most part avoid saying anything expressly; this nevertheless is the conclusion which the reader naturally draws--and was doubtless intended to draw--from Mr. Spencer's words. He gathers that these writers put forward an "utterly inadequate" theory, which cannot for a moment be entertained in the form in which they left it, but which, nevertheless, contains contributions to the formation of a just opinion which of late years have been too much neglected.
This inference would be, as Mr. Spencer ought to know, a mistaken one. Erasmus Darwin, who was the first to depend mainly on functionally produced modifications, attributes, if not as much importance to variations induced either by what we must call chance, or by causes having no connection with use and disuse, as Mr. Spencer does, still so nearly as much that there is little to choose between them. Mr. Spencer's words show that he attributes, if not half, still not far off half the modification that has actually been produced, to use and disuse. Erasmus Darwin does not say whether he considers use and disuse to have brought about more than half or less than half; he only says that animal and vegetable modification is "in part produced" by the exertions of the animals and vegetables themselves; the impression I have derived is, that just as Mr. Spencer considers rather less than half to be due to use and disuse, so Erasmus Darwin considers decidedly more than half--so much more, in fact, than half as to make function unquestionably the factor most proper to be insisted on if only one can be given. Further than this he did not go. I will quote enough of Dr. Erasmus Darwin's own words to put his position beyond doubt. He writes:-
"Thirdly, when we enumerate the great changes produced in the species of animals before their nativity, as, for example, when the offspring reproduces the effects produced upon the parent by accident or culture, or the changes produced by the mixture of species, as in mules; or the changes produced probably by exuberance of nourishment supplied to the foetus, as in monstrous births with additional limbs; many of these enormities are propagated and continued as a variety at least, if not as a new species of animal. I have seen a breed of cats with an additional claw on every foot; of poultry also with an additional claw and with wings to their feet; and of others without rumps. Mr. Buffon" (who, by the way, surely, was no more "Mr. Buffon" than Lord Salisbury is "Mr. Salisbury") "mentions a breed of dogs without tails which are common at Rome and Naples--which he supposes to have been produced by a custom long established of cutting their tails close off." {102a}
Footnote {102a} "Zoonomia," vol. i., p. 505.
Here not one of the causes of variation adduced is connected with use and disuse, or effort, volition, and purpose; the manner, moreover, in which they are brought forward is not that of one who shows signs of recalcitrancy about admitting other causes of modification as well as use and disuse; indeed, a little lower down he almost appears to assign the subordinate place to functionally produced modifications, for he says--"Fifthly, from their first rudiments or primordium to the termination of their lives, all animals undergo perpetual transformations; WHICH ARE IN PART PRODUCED by their own exertions in consequence of their desires and aversions, of their pleasures and their pains, or of irritations or of associations; and many of these acquired forms or propensities are transmitted to their posterity."
I have quoted enough to show that Dr. Erasmus Darwin would have protested against the supposition that functionally produced modifications were an adequate explanation of all the phenomena of organic modification. He declares accident and the chances and changes of this mortal life to be potent and frequent causes of variations, which, being not infrequently inherited, result in the formation of varieties and even species, but considers these causes if taken alone as no less insufficient to account for observable facts than the theory of functionally produced modifications would be if not supplemented by inheritance of so-called fortuitous, or spontaneous variations. The difference between Dr. Erasmus Darwin and Mr. Spencer does not consist in the denial by the first, that a variety which happens, no matter how accidentally, to have varied in a way that enables it to comply more fully and readily with the conditions of its existence, is likely to live longer and leave more offspring than one less favoured; nor in the denial by the second of the inheritance and accumulation of functionally produced modifications; but in the amount of stress which they respectively lay on the relative importance of the two great factors of organic evolution, the existence of which they are alike ready to admit.
With Erasmus Darwin there is indeed luck, and luck has had a great deal to do with organic modification, but no amount of luck would have done unless cunning had known how to take advantage of it; whereas if cunning be given, a very little luck at a time will accumulate in the course of ages and become a mighty heap. Cunning, therefore, is the factor on which, having regard to the usage of language and the necessity for simplifying facts, he thinks it most proper to insist. Surely this is as near as may be the opinion which common consent ascribes to Mr. Spencer himself. It is certainly the one which, in supporting Erasmus Darwin's system as against his grandson's, I have always intended to support. With Charles Darwin, on the other hand, there is indeed cunning, effort, and consequent use and disuse; nor does he deny that these have produced some, and sometimes even an important, effect in modifying species, but he assigns by far the most important role in the whole scheme to natural selection, which, as I have already shown, must, with him, be regarded as a synonym for luck pure and simple. This, for reasons well shown by Mr. Spencer in the articles under consideration, is so untenable that it seems only possible to account for its having been advanced at all by supposing Mr. Darwin's judgment to have been perverted by some one or more of the many causes that might tend to warp them. What the chief of those causes may have been I shall presently point out.
Buffon erred rather on the side of ignoring functionally produced modifications than of insisting on them. The main agency with him is the direct action of the environment upon the organism. This, no doubt, is a flaw in Buffon's immortal work, but it is one which Erasmus Darwin and Lamarck easily corrected; nor can we doubt that Buffon would have readily accepted their amendment if it had been suggested to him. Buffon did infinitely more in the way of discovering and establishing the theory of descent with modification than any one has ever done either before or since. He was too much occupied with proving the fact of evolution at all, to dwell as fully as might have been wished upon the details of the process whereby the amoeba had become man, but we have already seen that he regarded inherited mutilation as the cause of establishing a new breed of dogs, and this is at any rate not laying much stress on functionally produced modifications. Again, when writing of the dog, he speaks of variations arising "BY SOME CHANCE common enough with nature," {104a} and clearly does not contemplate function as the sole cause of modification. Practically, though I grant I should be less able to quote passages in support of my opinion than I quite like, I do not doubt that his position was much the same as that of his successors, Erasmus Darwin and Lamarck.
Footnote {104a} See "Evolution Old and New." p. 122.
Lamarck is more vulnerable than either Erasmus Darwin or Buffon on the score of unwillingness to assign its full share to mere chance, but I do not for a moment believe his comparative reticence to have been caused by failure to see that the chapter of accidents is a fateful one. He saw that the cunning or functional side had been too much lost sight of, and therefore insisted on it, but he did not mean to say that there is no such thing as luck. "Let us suppose," he says, "that a grass growing in a low-lying meadow, gets carried BY SOME ACCIDENT to the brow of a neighbouring hill, where the soil is still damp enough for the plant to be able to exist." {105a} Or again--"With sufficient time, favourable conditions of life, successive changes in the condition of the globe, and the power of new surroundings and habits to modify the organs of living bodies, all animal and vegetable forms have been imperceptibly rendered such as we now see them." {105b} Who can doubt that accident is here regarded as a potent factor of evolution, as well as the design that is involved in the supposition that modification is, in the main, functionally induced? Again he writes, "As regards the circumstances that give rise to variation, the principal are climatic changes, different temperatures of any of a creature's environments, differences of abode, of habit, of the most frequent actions, and lastly of the means of obtaining food, self-defence, reproduction," &c. {105c} I will not dwell on the small inconsistencies which may be found in the passages quoted above; the reader will doubtless see them, and will also doubtless see that in spite of them there can be no doubt that Lamarck, while believing modification to be effected mainly by the survival in the struggle for existence of modifications which had been induced functionally, would not have hesitated to admit the survival of favourable variations due to mere accident as also a potent factor in inducing the results we see around us.
Footnote {105a} "Phil. Zool.," i., p. 80.
Footnote {105b} Ibid., i. 82.
Footnote {105c} Ibid. vol. i., p. 237.
For the rest, Mr. Spencer's articles have relieved me from the necessity of going into the evidence which proves that such structures as a giraffe's neck, for example, cannot possibly have been produced by the accumulation of variations which had their origin mainly in accident. There is no occasion to add anything to what Mr. Spencer has said on this score, and I am satisfied that those who do not find his argument convince them would not be convinced by anything I might say; I shall, therefore, omit what I had written on this subject, and confine myself to giving the substance of Mr. Spencer's most telling argument against Mr. Darwin's theory that accidental variations, if favourable, would accumulate and result in seemingly adaptive structures. Mr. Spencer well shows that luck or chance is insufficient as a motive-power, or helm, of evolution; but luck is only absence of design; if, then, absence of design is found to fail, it follows that there must have been design somewhere, nor can the design be more conveniently placed than in association with function.
Mr. Spencer contends that where life is so simple as to consist practically in the discharge of only one function, or where circumstances are such that some one function is supremely important (a state of things, by the way, more easily found in hypothesis than in nature--at least as continuing without modification for many successive seasons), then accidental variations, if favourable, would indeed accumulate and result in modification, without the aid of the transmission of functionally produced modification. This is true; it is also true, however, that only a very small number of species in comparison with those we see around us could thus arise, and that we should never have got plants and animals as embodiments of the two great fundamental principles on which it is alone possible that life can be conducted, {107a} and species of plants and animals as embodiments of the details involved in carrying out these two main principles.
Footnote {107a} See concluding chapter.
If the earliest organism could have only varied favourably in one direction, the one possible favourable accidental variation would have accumulated so long as the organism continued to exist at all, inasmuch as this would be preserved whenever it happened to occur, while every other would be lost in the struggle of competitive forms; but even in the lowest forms of life there is more than one condition in respect of which the organism must be supposed sensitive, and there are as many directions in which variations may be favourable as there are conditions of the environment that affect the organism. We cannot conceive of a living form as having a power of adaptation limited to one direction only; the elasticity which admits of a not being "extreme to mark that which is done amiss" in one direction will commonly admit of it in as many directions as there are possible favourable modes of variation; the number of these, as has been just said, depends upon the number of the conditions of the environment that affect the organism, and these last, though in the long run and over considerable intervals of time tolerably constant, are over shorter intervals liable to frequent and great changes; so that there is nothing in Mr. Charles Darwin's system of modification through the natural survival of the lucky, to prevent gain in one direction one year from being lost irretrievably in the next, through the greater success of some in no way correlated variation, the fortunate possessors of which alone survive. This, in its turn, is as likely as not to disappear shortly through the arising of some difficulty in some entirely new direction, and so on; nor, if function be regarded as of small effect in determining organism, is there anything to ensure either that, even if ground be lost for a season or two in any one direction, it shall be recovered presently on resumption by the organism of the habits that called it into existence, or that it shall appear synchronously in a sufficient number of individuals to ensure its not being soon lost through gamogenesis.
How is progress ever to be made if races keep reversing, Penelope- like, in one generation all that they have been achieving in the preceding? And how, on Mr. Darwin's system, of which the accumulation of strokes of luck is the greatly preponderating feature, is a hoard ever to be got together and conserved, no matter how often luck may have thrown good things in an organism's way? Luck, or absence of design, may be sometimes almost said to throw good things in our way, or at any rate we may occasionally get more through having made no design than any design we should have been likely to have formed would have given us; but luck does not hoard these good things for our use and make our wills for us, nor does it keep providing us with the same good gifts again and again, and no matter how often we reject them.
I had better, perhaps, give Mr. Spencer's own words as quoted by himself in his article in the Nineteenth Century for April, 1886. He there wrote as follows, quoting from section 166 of his "Principles of Biology," which appeared in 1864:-
"Where the life is comparatively simple, or where surrounding circumstances render some one function supremely important, the survival of the fittest" (which means here the survival of the luckiest) "may readily bring about the appropriate structural change, without any aid from the transmission of functionally- acquired modifications" (into which effort and design have entered). "But in proportion as the life grows complex--in proportion as a healthy existence cannot be secured by a large endowment of some one power, but demands many powers; in the same proportion do there arise obstacles to the increase of any particular power, by 'the preservation of favoured races in the struggle for life'" (that is to say, through mere survival of the luckiest). "As fast as the faculties are multiplied, so fast does it become possible for the several members of a species to have various kinds of superiority over one another. While one saves its life by higher speed, another does the like by clearer vision, another by keener scent, another by quicker hearing, another by greater strength, another by unusual power of enduring cold or hunger, another by special sagacity, another by special timidity, another by special courage; and others by other bodily and mental attributes. Now it is unquestionably true that, other things equal, each of these attributes, giving its possessor an equal extra chance of life, is likely to be transmitted to posterity. But there seems no reason to believe it will be increased in subsequent generations by natural selection. That it may be thus increased, the animals not possessing more than average endowments of it must be more frequently killed off than individuals highly endowed with it; and this can only happen when the attribute is one of greater importance, for the time being, than most of the other attributes.
If those members of the species which have but ordinary shares of it, nevertheless survive by virtue of other superiorities which they severally possess, then it is not easy to see how this particular attribute can be developed by natural selection in subsequent generations." (For if some other superiority is a greater source of luck, then natural selection, or survival of the luckiest, will ensure that this other superiority be preserved at the expense of the one acquired in the earlier generation.) "The probability seems rather to be, that by gamogenesis, this extra endowment will, on the average, be diminished in posterity--just serving in the long run to compensate the deficient endowments of other individuals, whose special powers lie in other directions; and so to keep up the normal structure of the species. The working out of the process is here somewhat difficult to follow" (there is no difficulty as soon as it is perceived that Mr. Darwin's natural selection invariably means, or ought to mean, the survival of the luckiest, and that seasons and what they bring with them, though fairly constant on an average, yet individually vary so greatly that what is luck in one season is disaster in another); "but it appears to me that as fast as the number of bodily and mental faculties increases, and as fast as the maintenance of life comes to depend less on the amount of any one, and more on the combined action of all, so fast does the production of specialities of character by natural selection alone become difficult. Particularly does this seem to be so with a species so multitudinous in powers as mankind; and above all does it seem to be so with such of the human powers as have but minor shares in aiding the struggle for life--the aesthetic faculties, for example.
"Dwelling for a moment on this last illustration of the class of difficulties described, let us ask how we are to interpret the development of the musical faculty; how came there that endowment of musical faculty which characterises modern Europeans at large, as compared with their remote ancestors? The monotonous chants of low savages cannot be said to show any melodic inspiration; and it is not evident that an individual savage who had a little more musical perception than the rest would derive any such advantage in the maintenance of life as would secure the spread of his superiority by inheritance of the variation," &c.
It should be observed that the passage given in the last paragraph but one appeared in 1864, only five years after the first edition of the "Origin of Species," but, crushing as it is, Mr. Darwin never answered it. He treated it as nonexistent--and this, doubtless from a business standpoint, was the best thing he could do. How far such a course was consistent with that single-hearted devotion to the interests of science for which Mr. Darwin developed such an abnormal reputation, is a point which I must leave to his many admirers to determine. _