George John Romanes

“ Of course the theory of descent with adaptive modification has a delightfully simple answer to supply, viz., that when, from changed conditions of life, an organ which was previously useful becomes useless, natural selection, combined with disuse and so-called economy of growth, will cause it to dwindle till it becomes a rudiment. On the other hand, the theory of special creation can only maintain that these rudiments are formed for the sake of adhering to an ideal type. ”

“ On the contrary, there is the best evidence to show that since the first dawn of life in the occurrence of the simplest organisms, until the meridian splendour of life as now we see it, gradual advance from the general to the special—from the low to the high, from the few and simple to the many and complex—has been the law of organic nature. And of course it is needless to say that this is precisely the law to which the process of descent with adaptive modification would of necessity give rise. ”

“ But when a theory has been raised to such a level of probability as this, it is, for all practical purposes, as good as a demonstration. Thus, in the particular instance before us, even if the sceptical demand for evidence, which from the nature of the case is clearly impossible, were granted, and if we could actually observe the transmutation of species, the fact would not exert any further influence on the progress of science than is now exerted by the large and converging bodies of evidence which leave no other rational theory open to us than that such transmutation has taken place. ”

“ This now seems most absurd to us; but to posterity it will not seem nearly so much so as that, notwithstanding such precedents, persons should still be found to object to Darwin's discovery, not because they were anxious to maintain the dignity of the heavenly bodies, but because they were so ludicrously anxious to maintain the dignity of their own! Good it is for man, puffed up with such silly pride, that Nature teaches him humility. ”

“ For, be it observed, a scientific or natural classification differs very much from a popular or hap-hazard classification, and the difference consists in this, that while a popular classification is framed with exclusive reference to the external appearance of organisms, a scientific classification is made with reference to the whole structure. A whale, for instance, is often thought to be a fish, because it resembles a fish in form and habits; whereas dissection shows that it is beyond all comparison more unlike a fish than it is like a horse or a man. ”

“ I am not intolerant, because I believe that dissent from the general doctrine of evolution can only arise either from ignorance of some special departments of science, or from a bias of feeling against the doctrine—to both of which weaknesses evolutionists can afford to be indulgent. ”

“ Now, if this process of continuously adapting organisms to their environment takes place in nature at all, there is no reason why we should set any limits on the extent to which it is able to go up to the point at which a complete and perfect adaptation is achieved. Therefore we might suppose that all species would attain to this condition of perfect adjustment to their environment, and there remain fixed. ”

“ I have no doubt, however, that the principal obstacle which the doctrine of evolution encounters in the popular mind is not one of reason, but of sentiment. It is thought that the conception of man being a lineal descendant of the monkey is a conception which is degrading to the dignity of the former animal. ”

“ Mivart pointed to this fact as a great difficulty in the way of the theory of evolution by natural selection, because it must clearly be a most improbable thing that so complicated a structure as the eye of a fish should happen to be arrived at through each of two totally different lines of descent. And this difficulty would, indeed, be almost fatal to the theory of evolution by natural selection, if the apparent similarity were a real one. ”

“ For, be it observed, the exception in limine to the evidence which we are about to consider, does not question that natural selection may not be able to do all that Mr. Darwin ascribes to it: it merely objects to his interpretation of the facts, because it maintains that these facts might equally well be ascribed to intelligent design. And so undoubtedly they might, if we were all childish enough to rush into a supernatural explanation whenever a natural explanation is found sufficient to account for the facts. ”

“ However, adopting for the sake of argument this gigantic assumption, let us suppose that God laid down these arbitrary rules for His own guidance in creation, and let us see to what it leads. If, as is assumed, the Deity formed a certain number of ideal types, and determined that on no account should He allow any part of one type to appear in any part of another, surely we should expect that within the limits of the same type the same typical structures should always be present. ”

“ Darwin's theory, or, I may add, with any of the methods and results of natural science. The only position, therefore, which I here desire to render plain is that, if the doctrine of evolution is seen to be established by sufficient evidence, and therefore the causes which it sets forth are recognised as adequate to furnish a scientific explanation of the results observed, then the pg. 16 facts of organic nature necessarily fall into the same logical category, with reference to any question of design, as that of all or any other series of facts in the physical universe. ”

“ Now, it is perfectly right to draw a clear distinction between a theory and a demonstration; but it is a great mistake to suppose that a theory may then only be admitted by science when it has been demonstrated. Bishop Butler tells us that “Probability is the guide of life,” and not less true is it that probability is likewise the guide of science. ”

“ The Correspondence columns of Nature, while forming a medium of Scientific discussion and of intercommunication among the most distinguished men of Science, have become the recognized organ for announcing new discoveries and new illustrations of Scientific principles among observers of Nature all the world over—from Japan to San Francisco, from New Zealand to Iceland. ”

“ And forasmuch as natural selection may thus continue, ad infinitum, slowly to alter a specific type in adaptation to a gradually changing environment, if in any case the alteration thus effected is sufficient in amount to lead naturalists to denote the specific type by some different name, it follows that natural selection has transmuted one specific type into another. And so the process is supposed to go on over all the countless species of plants and animals simultaneously—the world of organic types being thus regarded as in a state of perpetual, though gradual, flux. ”

“ For the theory shows that if structures admit of being moulded to their special uses by natural selection, the same must be true of instincts; and it is found an easy matter to understand how, by seizing upon and fixing, through hereditary beneficial variations of habit (whether instinctive or intelligent) , natural selection is as competent to fashion the mental structure of an animal as it is to shape its bodily structure into agreement with the external conditions of life. ”

“ So that in the province of human psychology no less than in that of animal, the theory of natural selection, in showing itself competent to explain much which is otherwise inexplicable, is seen to derive a large additional measure of argumentative support. ”

“ But, of course, if the evidence is supposed not to be equal and parallel—i.e., if it is supposed that the theory of natural relation is not so competent a theory to explain the facts of adaptation as is that of intelligent design—then the objection is no longer the one that we are considering. It is quite another objection, and one which is not primâ facie absurd; it requires to be met by examining how far the theory of natural selection is able to explain the facts. ”

“ If so, it appears to me a most unfortunate circumstance, that throughout both the vegetable and animal kingdoms, all cases which can be pointed to as showing ingenious adaptation of the same typical structure to the performance of widely different functions, are cases which come within the limits of the same natural group of plants and animals, and therefore admit of being equally well explained by descent from a common ancestry ”

“ With the general aim of the present abstract being thus understood, I shall start at the beginning of my subject by very briefly describing the theory of natural selection. It is a pg. 3matter of observable fact that all plants and animals are perpetually engaged in what Mr. Darwin calls a “struggle for existence.” That is to say, in every generation of every species a great many more individuals are born than can possibly survive; so that there is in consequence a perpetual battle for life going on among all the constituent individuals of any given generation. ”

“ For, if thepg. 78 theory of special creation is true, I hold that as no one fact can be adduced in its favour, whilst so vast a body of facts can be adduced against it, the only possible explanation of so extraordinary a circumstance is that of a mendacious intelligence of superhuman power carefully disposing all the observable facts of his creation in such a way as to compel his rational creatures, by the best and most impartial use of their rational faculties, to conclude that the theory of evolution is as certainly true as the theory of special creation is conspicuously false. ”

“ In the first place, why is it that some structures are selected as typical and not others? Why should the vertebral skeleton, for instance, be tortured into every conceivable variety of modification in order to make it serviceable for as great a variety of functions; while another structure, such as the eye, is made in different sub-kingdoms on fundamentally different plans, notwithstanding that it has throughout to perform the same function? ”

“ To economise space, I shall not explain the considerations which obviously lead to the anticipation that, if the theory of descent by inheritance is true, the life history of the individual ought to constitute a sort of condensed epitome of the whole history of its descent. But taking this anticipation for granted, as it is fully realised by the facts of embryology, it follows that the pg. 64science of embryology affords perhaps the strongest of all the strong arguments in favour of evolution. ”

“ This being understood, I shall now proceed to render an epitome of the evidence in favour of organic evolution, and I shall do so by classifying the arguments in a way tending to show their distinct or independent character, and therefore calculated to display the additional force which they acquire from their cumulative nature. ”

“ The theory of evolution by natural selection supposes that hereditary characters admit of being slowly modified wherever their modification will render an organism better suited to a change in its conditions of life. ”

“ And this follows, not merely because in every generation it is only the flower of the race that is allowed to breed, but also because if in any generation some new and beneficial qualities happen to appear as slight variations from the ancestral type, these will be seized upon by natural selection and added, by transmission in subsequent generations, to the previously existing type. ”

“ The business of science, as of common life, is to estimate correctly the relative degrees of probability presented by this and that theory or hypothesis; when once a theory or hypothesis is demonstrated it ceases to be a matter of scientific inquiry, and becomes a matter of scientific fact. Thus received, we have to consider the doctrine of evolution as certainly standing in the first rank of scientific theories in respect of probability sustained by evidence, although no lesspg. ”

“ At any rate, to say the least, the law of parsimony forbids us to ascribe such effects to a supernatural cause, acting in so whimsical a manner, when the effects are precisely what we should expect to follow from the action of a highly probable natural cause. The classification of animal forms, indeed, as Darwin, Lyell, and Hæckel have pointed out, strongly resembles the classification of languages. In the case of languages, as in the case of species, we have genetic affinities strongly marked ”

“ But, on the other hand, if all the structures and instincts are supposed to be due to natural selection (whether alone or in conjunction with other natural causes) , we have no need to feel staggered at flagrant cases of imperfection; we have only to wonder at the number of cases in which perfection, more or less complete, has been attained. ”

“ As Darwin observes, “there is hardly a climate or condition in the Old World which cannot be paralleled in the New ... and yet how widely different are their living productions.” And that it is not the suitability of organismspg. 61 to the areas which they inhabit which has determined their creation upon those areas, is conclusively proved by the effects of the artificial transportation of species by man. For in such cases it frequently happens that the imported species thrives quite as well in its new as in its old home, and indeed often supplants the native species. ”

“ Now, in this struggle for existence, which individuals will be victorious and live? Assuredly those which are best fitted to live: the weakest and the least fitted to live will succumb and die, while the strongest and the best fitted to live will be triumphant and survive. ”

“ Similarly in all oceanic islands situated more than three hundred miles from land, no species of the whole class of mammals is to be found, excepting species of the only order of mammals which can fly, viz., bats. And, as if to make the case still stronger, these forlornly created species of bats sometimes differ from all other bats in the world. But can we, as reasonable men, suppose that the Deity has chosen, without any apparent reason, never to create any frog, toad, newt, or mammal on any oceanic island,pg. 55 save only such species as are able to fly? ”