The Old Riddle And The Newest Answer Part 9

XIV

ORGANIC EVOLUTION

We have now considered the question of Evolution in the larger and more fundamental signification of the term to which, as we noted at starting, very different meanings are attached; and at this stage of our discussion it will be convenient to sum up the main conclusions at which we have arrived.

It is, in the first place, unwarrantable to pretend that the discoveries of modern Science, brilliant and marvellous as they undoubtedly are, have thrown any light upon the origin of the Material Universe, or of its forces, or of the laws according to which its operations proceed.

Nor has Science anything to tell as to the origin of life, of sensation, or of reason. Nothing as yet discovered by her, or which she can discern any prospect of discovering, adds aught to our knowledge regarding such points as these.

Therefore, to say that the doctrine of Evolution as affirmed by Science, explains the existence of the world we know, is untrue and unscientific.

Moreover, we have seen that, as a factor without which the Order of Nature is unintelligible, the First Cause to which her existence is owing must be possessed of Intelligence, determining her processes according to its purposes. Hence it follows that no system of philosophy satisfies our reason which would find the ultimate explanation of all things in the forces of matter themselves which it is the province of Science to investigate.

On the other hand, in maintaining that Purpose must needs have acted, we do not a.s.sume to p.r.o.nounce as to the manner of its action. To say that Purpose rules every detail in the making or development of the universe, does not by any means signify that it interferes at every step with the laws of Nature. Rather, these laws are the expression of Purpose,--its machinery to secure its designed result. a.s.suming, for instance, the primeval existence of Professor Huxley's cosmic nebula, so const.i.tuted that the actual world was bound naturally to issue from it, as does a chicken from an egg, or an oak from an acorn,--while we find it inconceivable that such a piece of mechanism should originate without an intelligence to design it,--we have no difficulty in supposing that intelligence to have exhibited itself once for all at the first beginning, and to have fashioned the actual world by shaping the causes or conditions by which it was to be produced, thus making everything, not directly and immediately but as St. Augustine held "_causaliter et seminaliter_."

There remains for consideration Evolution in its narrower sense, in which its operations are restricted to organic nature, such Evolution being commonly, but incorrectly, identified with "Darwinism." Understood thus, "Evolution" signifies no more than that the various species of animals and plants have descended _genetically_ one from another, through a graduated series of intermediate forms which link them together. _Darwinism_ is one particular mode of explaining how such transformations may be accounted for,--namely, by what is known as "Natural Selection." The theory of Evolution, as thus concerned with Organic life in particular, is compendiously described as "Transformism," under which head Darwinism is evidently included.

Transformism makes no pretence to account for the origin of life, whether animal or vegetable. Living things must exist before any question arises as to their trans.m.u.tation. But, given the existence of life, Transformists undertake in the first place to show that Organic Evolution has, as a matter of fact, occurred, and is still in process of occurrence; and secondly, to exhibit the manner in which this process is actually worked out. As to the first point, all Transformists, whether Darwinians or others, are necessarily at one, for the fact of Evolution is equally essential for every explanation of its method. It is when they come to explain in what manner evolutionary transformations have been wrought that Transformists divide themselves into various schools, each of which relies upon some particular factor to furnish the required explanation. Thus besides Darwinians pure and simple, there are neo-Darwinians, Lamarckians, neo-Lamarckians, Weismannists, and others, ascribing the results to physiological selection, s.e.xual-selection, or other forces, rather than natural selection. Of such systems, however, excepting only Darwinism, it will be unnecessary to speak in particular.

The great fundamental question is whether genetic Evolution be really established as a fact,--which, as has been said, equally affects them all--and if it be advisable to treat more in detail of Darwinism, it is not because this does not hold good of it as of the rest--but because this particular system has obtained such a position, is so much in the mouths of men, and has been made the basis of so many and such far-reaching consequences, that it is impossible to pa.s.s it by.

Much the same may indeed be said even of the a.s.sumed fact of Organic Evolution underlying all Transformist theories. This does not affect the fundamental problems with which we are concerned, and leaving untouched, as it does, the question of the origin of Life it makes even less pretence than the cosmic-nebular hypothesis just spoken of to trace the operations of Nature to their ultimate source. It might therefore appear superfluous to devote to it so much attention as, if treated at all, it must needs demand.

But, whatever may thus appear from the point of view of strict logic, it is abundantly evident that in common estimation the a.s.sumed fact of Organic transformation is the foundation-stone of Evolutionary systems of every kind. And not unnaturally; for here at last we have something with which Science can deal, strictly according to her own methods. If she knows, and can know, nothing from actual observation concerning the first beginnings of matter, of the cosmic nebula, or of life, it is quite otherwise with the history of living things since they first appeared, and with the phenomena of life as it exists and is propagated.

Here are questions which are strictly scientific, forming the subject-matter of Palaeontology and Biology, and these Sciences supplemented by others, such as Geology, Physical Geography, and Astronomy, furnish a ma.s.s of evidence bearing upon the subject of Organic Evolution. When therefore the great majority of men of Science, declare that the fact of genetic Transformism is established beyond the possibility of doubt, Evolutionists find themselves supplied with a plausible foothold on which to stand and rest their fulcrum, while, like Archimedes, they proceed to move the world.

That men of Science generally thus agree, cannot be questioned, and although this agreement is by no means so universal as is popularly supposed, there is no doubt that were the question to be settled by enumeration of the authorities on either side, Transformism would win easily. It may also be freely acknowledged, that Transformism in general and Darwinism in particular are theories to which on _a priori_ grounds no exception need be taken, and that, so far at least as concerns their general scope, apart from the origin of Man, no one can reasonably start with a prepossession against them. Nay, we will go farther, and say that to our way of thinking it appears immensely more probable, that things should always have gone on as they go on now, by the operation of the same natural laws, and that specific forms should have been naturally produced, as individuals of a species are produced now, by generation,--rather than that not only repeated acts of specific creation, but any operations totally different from those we witness, should have occurred to interrupt, and as we should judge, to mar, the Law of Continuity.

All this is true. But we are engaged on a scientific enquiry,--and if there be one principle more than another upon which Science insists, it is that we should prove all things, not by authority, but by evidence,--and that we should seek evidence, not in pre-conceived ideas as to what should be, but in observation of what is. Accordingly, while we are most ready to accept Transformism or Darwinism should we find solid reasons for doing so, we are bound, for the sake of Science, to demand unimpeachable proofs before subscribing to doctrines which are made responsible for so much.

Before proceeding farther it will be necessary to exhibit more in detail the exact character of the question we have to discuss.

According to the celebrated "Formula" of Mr. Herbert Spencer--"Evolution is an integration of matter and concomitant dissipation of motion; during which the matter pa.s.ses from a relatively indefinite, incoherent h.o.m.ogeneity, to a relatively definite, coherent heterogeneity; and during which the contained motion undergoes a parallel transformation."

It would be interesting to know what idea this definition conveys to many of those who are in the habit of quoting it, but, so far as organic Evolution is concerned, it must mean that whereas in the earlier and lower forms of life one organ performed many different functions in an imperfect manner, evolutionary development has gradually produced higher forms, in which each function has its special organ, by which it is more perfectly discharged. As an extreme instance of the former condition, the Hydra has but two organs, an outside which respires, and an inside which digests. If it be turned inside out these functions are reversed; the skin becoming the stomach, and the stomach the skin. Thus Evolution has been an ascending process from the lower to the higher, from the less to the more organized.

Such, it must be added, has undoubtedly been the course of life. Amongst plants and animals alike, it began with lower and simpler forms, after which succeeded in due order others more developed and elaborately organized, the order in which they came upon the scene being much the same as that in which we should naturally arrange their specimens in a museum. Thus in the vegetable kingdom, first came such growths as sea-weeds and fungi, followed by ferns and club-mosses,--yews and pines,--and so through gra.s.ses, canes, and palms, to the highest group in which are included our forest trees and the bulk of our garden flowers. In like manner, the animal series,--to mention only leading groups of which evidence is found,--starting with almost structureless _Protozoa_, followed by such forms as starfish and sponges, worms, molluscs and crustaceans, has advanced to vertebrate creatures--fishes, amphibians, reptiles, birds, mammals,--and finally to man.

Thus, in a quite intelligible sense, there has certainly been Evolution, or development,--that is to say, an orderly progression from lower types to higher, throughout the history of life on earth, from its commencement to the present time. But, this is not the point. Was such Evolution or development _genetic_? Was it wrought by descent with modification of form from form? _That_ is what we have to enquire. If this has not been so, there has been no Evolution in the sense intended by Evolutionists.

According to their highest authority, Mr. Herbert Spencer, Evolution means "the production of all organic forms by the acc.u.mulation of modifications and of divergences by the addition of differences to differences."

Beyond all question [he adds] unlikenesses of structure gradually arise among the members of successive generations. We find that there is going on a modifying process of the kind alleged as the source of specific differences, a process which, though slow, does, in time, produce changes--a process which to all appearance would produce in millions of years any amount of changes.[176]

The Transformist doctrine is, therefore, that one species of plants or animals, has in natural course grown out of another, through the aggregation of changes each exceedingly minute. Darwinism adds that the ruling principle of this process is Natural Selection. These are the points on which our enquiry turns, and we may conveniently commence with the second.

XV

DARWINISM

It must first be observed that special consideration of Mr. Darwin's theory is rendered necessary even more imperatively on account of the claims advanced on his behalf by others, than of those to which he himself made any pretence. Without question the idea prevails almost universally, that he has furnished a scientific explanation of all organic phenomena through the operation of purely natural laws, and has thus rendered obsolete the idea that any power beyond Nature is required in order to account for the totality of things, or that there are any features of the world which indicate the operation of intelligent purpose.

That such ideas should be widely prevalent amongst those who, having no special acquaintance with the subject, must depend for their knowledge on the popularizers of Science, is scarcely wonderful, for such teachers, with scarcely an exception, so declare, and occasionally real men of Science lend the weight of their authority to similar statements.

It will be sufficient to cite Professor Haeckel, who writes thus:[177]

It seemed to Kant so impossible to explain the orderly processes in the living organism without postulating super-natural final causes (that is, a purposive creative force) that he said, "It is quite certain that we cannot even satisfactorily understand, much less elucidate, the nature of an organism and its internal faculty on purely mechanical natural principles--it is so certain, indeed, that we may confidently say: It is absurd for a man even to conceive the idea that some day a Newton will arise who can explain the origin of a single blade of gra.s.s by natural laws uncontrolled by design. Such a hope is entirely forbidden us." Seventy years afterwards this impossible Newton of the organic world appeared in the person of Charles Darwin, and achieved the great task that Kant had deemed impracticable.

It is quite impossible to understand how such an a.s.sertion can be made by any one who knows the facts. Not only did Mr. Darwin never profess to have achieved any thing of the kind,--he repeatedly and distinctly disclaimed and repudiated any such supposition. Thus at the very end of his life (August 28, 1881) he wrote concerning one who had spoken of him like Professor Haeckel:

He implies that my views explain the universe; but it is a most monstrous exaggeration. The more one thinks, the more one feels the hopeless immensity of man's ignorance. If we consider the whole universe, the mind refuses to look at it as the outcome of chance.[178] The whole question seems to me insoluble.

But it should not be necessary to appeal to such disclaimers in order to show how absolutely unwarrantable are the pretensions made on Mr.

Darwin's behalf to have solved, or to have attempted to solve, the fundamental problems which scientific research unceasingly suggests but has never been able to elucidate. It should be quite sufficient to examine his theory as it actually is, and although its scope is immensely less ambitious than has been represented, it still occupies, even in its genuine form, a position of sufficient importance to challenge investigation.

Mr. Darwin's famous and epoch-making book, published in November, 1859, was ent.i.tled _On the Origin of Species by means of Natural Selection, or the Preservation of Favoured Races in the Struggle for Life_. In it he undertook to show how from one species[179] of animals or plants, another, quite distinct from it, may be derived by means of processes which go on in Nature every day, through the acc.u.mulation of minute differences occurring in successive generations, and guided to their collective result by the force of "Natural Selection." As man, he argues, has by means of selection been able to produce in a brief s.p.a.ce such astonishing varieties among his domestic animals and plants--as dogs, pigeons, roses or apples,--Nature, with the practically unlimited ages of geological time at her disposal, must be able to produce far greater and more enduring transformations, through the acc.u.mulation of minute differences, such as those upon which man has worked,--if only a factor can be found which amid the infinity of diverse and discordant variations spontaneously occurring, could, like the breeder or the gardener, pick out those leading to one particular result, and thus secure its accomplishment. Such a force Mr. Darwin conceives is found in "Natural Selection," which he thus explains.

The tendency of organic life, whether vegetable or animal, being to propagate itself enormously,--and the life-sustaining capacity of the earth being limited,--it necessarily follows that only a fraction of the creatures which are born can survive to maturity, and that while those best fitted to live will live, those less well fitted will die. Thus, there is set up a constant struggle for existence, in which every advantage, however slight, must tell, so that those possessing such advantages in one generation will be the parents of the next. But in the course of propagation, the offspring never exactly reproduce the parent form, from which they vary, some in one way some in another, and as some of these variations cannot help being advantageous to their possessors in the struggle, we have here the required factor for the production of new forms. Any thus beneficially equipped, (although the variation, and consequently the advantage, must in each instance be exceedingly slight,) will have the chances on their side against their less favoured fellows, whom in the long run they will supplant. And as their offspring, or some of them, will carry the profitable variation somewhat further, the stream of life will thus be set in such a direction as will ultimately bring about what might at first appear impossible metamorphoses.

Thus, to take a simple and favourite ill.u.s.tration,[180] winged insects inhabiting an island far from other land, are liable to be blown out to sea and drowned. It is in consequence, an advantage to them to have their power of flight curtailed, or taken away, and consequently in such situations their wings are generally found to be so reduced as to permit little or even nothing in the way of flying. Or to take an example of another kind,[181] the extraordinary length of neck which characterizes the giraffe enables it to browse on the higher branches of trees inaccessible to other vegetable feeders, and thus gives it an advantage over them in times of drought and scarcity of fodder. It can accordingly be easily understood, how its present structure has resulted from gradual elongations of the neck, each conferring on its possessor a slight advantage.

The work attributed to Natural Selection in such instances, though no doubt highly important, is comparatively facile, and it would be difficult to say that it could not be accomplished. But Mr. Darwin ascribes to the same factor, not merely such modification of existing structures, but the creation of entirely new mechanisms for specific purposes. We have, for instance, heard his description of the eye and its manifold "inimitable contrivances:" yet all these, he persuaded himself, might be thus accounted for. The idea, he confessed,[182] seems at first sight preposterous; yet, though not without much difficulty,[183] he succeeded in convincing himself, that given the rudest and most rudimentary form of eye to start with--no more than a nerve sensitive to light but incapable of forming an image--Natural Selection might develop therefrom, through an infinite series of gradations the inconceivably complex machine that is now found in the higher vertebrates,[184] and the totally different but equally marvellous organs of sight possessed by insects, crustaceans, and other creatures.

In like manner, Mr. Darwin contended, might the most complex and wonderful instincts be generated. As an example may be cited that by which the hive-bee constructs its combs--of which he thus speaks:[185]

He must be a dull man who can examine the exquisite structure of a comb, so beautifully adapted to its end, without enthusiastic admiration. We hear from mathematicians that bees have practically solved a recondite problem, and have made their cells of the proper shape to hold the greatest possible amount of honey, with the least possible consumption of precious wax in their construction. It has been remarked that a skilful workman with fitting tools and measures, would find it very difficult to make cells of wax of the true form, though this is perfectly effected by a crowd of bees working in a dark hive.[186] Granting whatever instincts you please, it seems at first sight quite inconceivable how they can make all the necessary angles and planes, or even perceive when they are correctly made. But the difficulty is not nearly so great as it at first appears: all this beautiful work can be shown, I think, to follow from a few simple instincts.

He accordingly proceeds to argue, that beginning with circular cells, like those of Humble Bees, and progressing through an intermediate form, circular where free, but with flat part.i.tion walls where two or more cells touch one another, it is quite possible to suppose that Natural Selection has effected the whole improvement, those insects which accomplished any advance towards more scientific workmanship, and thus made materials go further, having been able to secure a livelihood better than their compet.i.tors.

Such in brief outline is the Darwinian system, which undertakes to account for all the alleged facts of Organic Evolution by means of the above factor, variously described as "Natural Selection," or the "Survival of the fittest in the Struggle for Existence." It should be remembered, though it is constantly forgotten, that it is this particular theory as to the working-cause of evolutionary transformations which is the essence of Darwinism. Mr. Darwin did not originate the idea of genetic transformism, which is almost necessarily suggested by the systematic development of life-forms to which Geology bears witness. Consequently, long before he came on the scene, the doctrine of transformation had been propounded, especially by Lamarck, and if it had met with no general acceptance, this was chiefly because no force was indicated which seemed to offer a satisfactory account of the mode in which the required changes could have been wrought. Such a force Mr. Darwin's "Natural Selection" was widely taken to furnish, and his theory was eagerly welcomed and adopted by those who only required such a basis on which to ground beliefs to which they were already predisposed, and Darwinism thus obtained that pre-eminent position which it still retains, at least in popular estimation.

Two special arguments may here be mentioned, which, although they really apply to all systems of Organic Evolution, have obtained a prescriptive right to be quoted particularly in favour of Darwinism, their bearing on which is easily seen.

The first is based on the frequent occurrence of "rudimentary,"

"fragmentary," or "vestigial" structures in animals and plants, which, although now seemingly useless, or even harmful, to their possessors, may be a.s.sumed to have been of service to their ancestors, but under changed conditions to have been thrown out of work by Natural Selection, and atrophied by disuse. Such are--the splint-bones of the horse, representing lost digits,--the rudimentary legs of some whales and serpents,--the _mammae_ and mammary glands of male mammals; and in the vegetable kingdom,--the aborted pistil in male florets of some _compositae_,--the useless corolla of certain wind-fertilized flowers, as _plantago_, and indeed the whole floral apparatus of plants which, like Wordsworth's pet the Lesser Celandine,[187] seldom ripen their seeds, but depend on other methods of propagation. The other fact cited on behalf of Darwinism is unquestionably very striking. In the course of their embryonic development, and even in the initial stages of their life after birth, higher animals pa.s.s through various phases in which they exhibit the characteristics of lower forms. Thus all life starts from a cell, in which there is nothing to shew whether it is ever to be anything more than a cell, or is to evolve a plant or animal,--nor, in this latter case, what sort of animal it is to be--a mollusc, for instance, a frog, or a mammal. At a later stage[188] it is impossible to distinguish the embryos of lizards, birds, and mammals except by size.

Even the human fetus at an early period bears vestiges of gill-clefts or arches, pointing to an aquatic existence. When the extremities come to be developed,[189] "The feet of lizards and mammals, the wings and feet of birds, no less than the hands and feet of man, all arise from the same fundamental form." The young of flat-fish such as soles and turbots, when they leave the egg are not flat, but shaped like ordinary fish, and they wear their eyes in the normal fashion, one on each side of their head, not both on the same side like their parents--whose form however they presently by degrees a.s.sume. Young lions and black birds are spotted, showing their affinity respectively to panthers and thrushes--and so on in numberless instances. All such features, it is a.s.sumed, indicate the _phylogeny_ of each animal, or the history of the race to which it belongs. As Professor Milnes Marshall succinctly put the matter:[190]

The phases through which an animal pa.s.ses in its progress from the egg to the adult are no accidental freaks, no mere matters of developmental convenience, but represent more or less closely ...

the successive ancestral stages through which the present condition has been acquired. Evolution tells us that each animal has had a pedigree in the past. Embryology reveals to us this ancestry, because every animal in its own development repeats this history, climbs up its own genealogical tree.