I. The unity of the human race raises some general questions, and entails consequences which we must now examine.
The first question which is suggested to the mind is evidently that oforigin. Without abandoning the strictly scientific aspect of the subject, that is to say, confining ourselves to the results of experiment and observation, can we explain the appearance on our globe of a being which forms a kingdom by itself? I do not hesitate to reply in the negative.
Let us admit at starting that we cannot consider separately the question of the human origin. Whatever may be the cause or causes which preside over the birth or the development of the organic kingdom, it is to them that the origin of all organised and living bodies must be traced. The similarity between all the essential phenomena which they exhibit, the identity of the general laws which govern them, render it impossible to suppose that it can be otherwise. The problem then of the origin of mankind becomes identical with that of all animal and vegetable species.
II. This problem has been approached very frequently and by many methods. But here we can only take into accountthe attempts which have been made in the name of science. Nor can these possess any interest for us until the time when it was at least possible to make a clear statement of the question, which was impossible as long as no clear definition had been given oforganic species. In an historic account of the attempts which have been made to solve the question, it is useless, therefore, to go further back than Ray and Tournefort. The publication of Maillet in 1748 is the first attempt which deserves passing attention.
I do not intend to repeat here the account which I have given elsewhere of the different theories proposed by that talented author, by Buffon, Lamarck, Et. Geoffroy St.-Hilaire, Bory de St.-Vincent, and by Naudin, Gaudry, Wallace, Owen, Gubler, Kölliker, Haeckel, Filippi, Vogt, Huxley, and Mme. Royer. They all have this point in common; they connect the origin of the more highly developed species with transmutations undergone by inferior species. But there the resemblance ceases, and their theories frequently differ entirely on all other points. In short, their ideas may be arranged in two principal groups according as their authors favour arapidor agradual transmutation. The former admit the sudden appearance of a new type produced by a being entirely different: according to them the first bird came from the egg of a reptile. The latter maintain that the modifications are always gradual, that between one species and another a number of links have intervened which unite the two extremes. They consider that types are only multiplied slowly, and by a progressive differentiation.
In reality the first of these two theories has never been stated in such a manner as to form a real doctrine; it has never formed a school. The philosophers who promoted it confined themselves most frequently to pointing out, in a general manner, thepossibilityof the phenomenon, while they attributed it to some accident. At most they invoke in aid of this possibility, some analogies borrowed from the history of ordinary individual development, from that ofalternate generation, or of hyper-metamorphosis; they produce no definite fact in justification of their assertions.
With the exception perhaps of the hypothesis of M. Naudin, which we shall presently discuss, all these theories which favour a rapid transmutation deserve a still graver reproach, that, namely, of neglecting the great general facts exhibited by the organic kingdom. An explanation of the multiplication and the succession of principal or secondary types by some hypothesis is not sufficient. Special account must be taken of the relations which connect these types, of the order which rules the whole and which has been maintained from remote geological periods through all the revolutions of the globe, and in spite of changes in fauna and flora.
Accident, without rule or law, when invoked as the immediate cause of special transmutations, is obviously incapable of explaining this important fact; it gives no explanation whatever of the generality of fundamental types, and of the direct or lateral affinities which exist between their derivatives.
It is different with the theories which favour gradual transmutation. They deal with all these important questions, and give a more or less plausible solution of them. They start from a certain number of principles whose consequences more or less explain the whole question and many of its details. In a word, they constitute genuine doctrines and it is but natural that they should have gained a certain number of adherents.
Unfortunately these theories all have the same radical fault. They agree with a certain number of important facts, connected essentially with the morphology of beings; but they are in direct contradiction with the fundamental phenomena of general physiology, which are no less general or fixed than the former. This contradiction is not evident at first sight. This is the reason why these doctrines have influenced not only the public at large, but even men of the highest intellect, whose sole error consists in their having allowed themselves to consider one side of the question only.
All these theories have been consolidated into the doctrine which rightly bears the name of Darwin. At the hands of this illustrious naturalist, the hypothesis of gradual transmutation has assumed a force and appearance of truth which it never possessed before. Doubtless, long before Darwin, Lamarck had formulated hislaw of heredityand hislaw of development of organs, to which the English naturalist has added nothing; M. Naudin had comparednatural selectiontoartificial selection; Etienne Geoffroy St.-Hilaire had promulgated the principle of thebalance of organs; Serres and Agassiz had recognized in embryogenic phenomena the representation of the genesis of beings. But by taking as a starting point thestruggle for existence; by explaining in this mannerselection; by fixing the results ofheredity; by replacing thepre-established lawsof Lamarck by the laws ofdivergence,continuity,permanent charactersand offinite heredity; by giving by these means an explanation of theadaptationof beings to all the conditions of existence, theexpansive powerof some, thelocalisationof others, the successivemodificationsof all, under the dominion of thelaws of compensation,economyand ofcorrelation of increase; by applying these facts to the past, present and future of animate creation, Darwin has formed a complete and systematic theory, the whole, and often the details, of which it is impossible not to admire.
I understand the fascination exercised by this profound and ingenious conception, which is supported by immense knowledge, and ennobled by his loyal honesty. I should doubtless have yielded as so many others have done, if I had not long understood that all questions of this kind depend especially upon physiology. Now, my attention once aroused, I found no difficulty in recognising the point at which the eminent author quits the ground of reality and enters upon that of inadmissible hypothesis.
I have thought it right to publish my criticisms upon the theory of transmutation, and upon Darwinism in particular. I was authorised to do so by the numerous attacks whichhave often been made, in no measured terms, against what I consider to be the truth, and against every opponent of the new theory. But while refuting theories I have always respected the authors and done justice to their work. I have quoted the good as well as the bad, and have always held aloof from the ardent and lamentable polemics raised by transmutation.
I have had great pleasure, when occasion has offered, in defending the splendid researches made by Darwin in the natural sciences. For this very reason, and at the risk of being considered narrow minded, enslaved to prejudices and unable to leave an old groove, etc., etc., I consider myself entitled to attack Darwinism, if I employ none but the weapons of science.
III. There are some points in Darwinism which are perfectly unassailable. We may consider as the most important thestruggle for existence, andselectionwhich is the result of it. It is not the first time, certainly, that the former has been established, and the important part it has to play in the general harmony of the world has at least been partly comprehended. I will here only recall to the mind of my readers the fables of La Fontaine. But no one had insisted, as Darwin has done, upon the enormous disproportion which exists between the number of births and the number of living individuals; no one had investigated, as he has, the general causes of death or of survival which produce the final result. By pointing out the fact that each species tends to increase in number in geometrical progression, which is proved by the number of offspring to which a single mother can give birth during the whole course of her life, the English naturalist makes it easy to comprehend the intensity of the struggles, direct or indirect, which are undergone by animals and plants against one another and the surrounding world. It is, most certainly, entirely owing to this struggle for existence, that the whole world, in a few years, is not overrun by some species, or the rivers and ocean filled in the same manner.
It is no less evident to me that the survivors cannot always owe their preservation to a combination of happy chances. Among the immense majority the victory can only be due to certain special advantages, which are not enjoyed by those who succumb. The result of thisstruggle for existenceis, then, the destruction of all the inferior individuals, and the preservation of those individuals only which possess some kind of superiority. This is what Darwin callsNatural Selection.
I can scarcely understand how these two phenomena can be doubted or even denied. They do not constitute a theory, but are facts. Far from being repugnant to the mind, they seem inevitable, the consequences follow with a sort of necessity and fatality resembling the laws of the inorganic world.
The termselectiongives rise to criticism, and the language of Darwin, at times too figurative, renders plausible the objection of those who have reproached him with attributing tonaturethe part of an intelligent being. The wordeliminationwould have been more exact. But much of this should have been prevented by the explanations given by the author. Besides, it is evident that the struggle for existence entails the elimination of individuals who are less able to sustain it, and that the result exactly resembles that produced byunconscious human selection. Thenheredityintervenes among beings which are free as well as among those which we bring up in captivity. It preserves and accumulates the progress made by each generation in any direction, and the final result is the production in the organism of certain appreciable anatomical and physiological modifications.
The wordssuperiorandinferiorshould here only be taken as relative to the conditions of existence in which animals and vegetables are placed. In other words the individual which is best adapted to those conditions, will be superior and will conquer in the struggle for existence. For instance, the black rat and the mouse have both to struggle against the brown rat which entered France during the lastcentury from the banks of the Volga. The black rat was almost as large and as strong as his adversary, but less ferocious and less prolific. It has been exterminated in spite of refuges which are inaccessible to its enemy. The mouse, which is much weaker, but at the same time much smaller, can retire into holes which are too small for the brown rat; it has therefore survived the black rat.
Is it possible to admit that selection and heredity act equally upon that indefinablesomethingwhich is connected with the rudimentary intelligence and instincts of animals? With Darwin I unhesitatingly reply in the affirmative. With animals, as with man, all the individuals of the same species have not an equal amount of intelligence and do not invariably possess the same aptitudes; certain instincts, like certain forms, are capable of modification. Our domestic animals furnish a number of examples of these facts. The wild ancestors of our dogs were certainly not accustomed to point at game. When left to themselves and placed under new conditions of existence, animals sometimes change their manner of life entirely. Beavers, from being disturbed by hunters, have dispersed; they have now abandoned the construction of their lodges and dig out long burrows in the banks of rivers. The struggle for existence must have been favourable to the first discoverers of this new method of escaping from their persecutors, and natural selection, while preserving them and their descendants, has converted a sociable and constructive animal into a solitary and burrowing one.
Up to this point it is evident that I agree in all that Darwin has said on the struggle for existence and natural selection. I disagree with him when he attributes to them the power of modifying organised beings indefinitely in a given direction, so that the direct descendants of onespeciesformanother speciesdistinct from the first.
IV. The fundamental cause of the disagreement arises evidently from the fact that Darwin had formed no clear conception of the sense which he attributed to the wordspecies. I have been unable to find in any of his works a single precise statement on this point. The accusation is more severe from being brought with justice against an author who claims to have discovered theorigin of species.
More frequently Darwin seems to adhere to a purely morphological idea, which is also somewhat vague. He often opposesspeciesandrace, which he also callsvariety, but without ever stating clearly what he understands by one or the other. He endeavours, moreover, to bring them together as closely as possible, though occasionally recognising some of the points which separate them. “The species,” he says in drawing one of his conclusions, “must be treated as an artificial combination which is necessary for convenience.” His disciples have followed him faithfully in this direction, and those who use the most explicit language on this subject, join their master in declaring that a species is only a kind of conventional group similar to those which are used in classification. As for races, they are only species undergoing transmutation. Now from what he has already learnt, short though the study has been, the reader knows, I hope, to which view he should adhere, and understands to what confusions such a vague kind of theory must lead.
In spite of the inevitable uselessness of a discussion of this kind, let us follow our adversaries into this unstable ground, and see whethermorphologicalfacts furnish their theory with the least probability.
Darwin himself, on several occasions, states that the result of selection is essentially to adapt animals and plants to the conditions of existence in which they have to live. Upon this point I agree with him entirely. If, however, harmony is once established between organised beings and the conditions of life, the struggle for existence and selection could only result in consolidating it and consequently their action is preservative.
If the conditions of life change they will again come into play in order to establish a new equilibrium, and modifications more or less marked will be the result of their action.But will these modifications be sufficiently great to give rise to a new species? The following fact will serve as a reply.
At the present time there is a stag in Corsica, which from its form has been compared to the badger-hound: its antlers differ from those of European stags. Those who confine themselves to morphological characters, will assuredly consider this as a distinct species, and it has often been considered to be so. Now Buffon preserved a fawn of this pretended species, and placed it in his park; in four years it became both larger and finer than the French stags which were older and considered finer grown. Moreover, the formal evidence of Herodotus, Aristotle, Polybius and Pliny attest that in their time there were no stags either in Corsica or Africa. Is it not evident that the stag in question had been transported from the continent to the island; that under the new conditions the species had undergone temporary morphological modification, though it had lost none of its power of resuming its primitive characters, when placed in its primitive conditions of life?
Are we, then, to conclude that in time nature could have completed the action, and entirely separated the Corsican stag from its original stock? We may answer in the negative, if any weight is to be attached to experience and observation.
Species partially subject to the rule of man furnish a number of facts which enable us to compare the power of natural forces, when abandoned to their own action, with that of man in modifying a specific type. In all artificial races varieties are infinitely more numerous, more varied and more marked than wild races and varieties. Now the result of these transmutations of organisms has only consisted in the formation ofraces, never in the formation of anew species. Darwin himself accepts this conclusion implicitly in his magnificent work on pigeons; for when speaking of theraces of pigeonshe only says that the difference of form is such that if they had been found in a wild state, we should have been compelled to make at least three or four genera of them. The wild rock pigeons, the original stock of all ourdomestic pigeons, only differ, on the contrary, in shades of colour.
The result is always the same, whenever we can compare the work of nature with our own. When he has anything to do with any vegetable or animal species,manalways changes its character, sometimes, after a lapse of some years, the change being much greater than that produced by nature since the species first came into existence. Theeffect of the conditions of life(milieu), of which we will speak presently, thestruggle for existenceandnatural selectionunderstood as I have just described it, the power which man possesses of directing natural forces and changing their resultant, easily explain this superiority of action.
Consequently, without leaving the domain of facts, and only judging from what we know, we can say that morphology itself justifies the conclusion that one species has never produced another by means of derivation. To admit the contrary is to call in theunknown, and to substitute apossibilityfor the results of experience.
Physiology justifies a still stronger assertion. Upon this ground also man is shown to be as powerful as nature, and for the same reasons. With our cultivated plants and domestic animals, it is not only the primitive form which has undergone change, but certain functions also. If we had only enlarged and deformed the wild carrot and the wild radish, it would not have become more eatable. To render it agreeable to our taste, the production of certain substances had to be reduced, and that of others enlarged, that is to say, nutrition and secretion had to be modified. If the functions in wild animal stocks had remained permanent, we should have had none of those races which are distinguished by a difference in the colour of the hair, in the production of milk, in aptitude for work, or in the production of meat. If instinct itself had not obeyed the action of man, we should not have had in the same kennel, pointers, grey-hounds, truffle dogs and terriers.
Nature produces nothing like this. To admit that similarresults will one day follow from the action of natural forces is to appeal to theunknown, topossibility, and runs counter to all laws of analogy, and all the results furnished by experience and observation.
Man’s superiority over nature is quite as clearly shown in the group of phenomena, which relate to the question with which we are now dealing.
We have seen how rare are the cases of natural hybrids among plants themselves; we have also seen that no cases are known among mammalia. Now since man has begun to make experiments in this direction, he has increased the number of hybrids among plants, and among animals also. Moreover, he has succeeded in preserving for more than twenty generations, a hybrid which he has been able to protect from reversion and disordered variation. But we know the care that was necessary to insure the continuance ofÆgilops speltæformis. If this plant had been left to itself, it would soon have disappeared.
The single exception which is known confirms therefore thelaw of sterilityamong species left to themselves. Now this law is in direct opposition to all the theories, which like Darwinism, tend to confuse species and race. This has been clearly understood by Huxley and has caused him to say, “I adopt the theory of Darwin under the reserve that proof should be given that physiological species can be produced by selective crossing.”
This proof has not yet been given, for it is a strange abuse of words to call by the name of species, the series of hybrids whose history I have given above, viz.: the leporides and the chabins. But even if the proof demanded by Huxley were furnished, it does not follow that the greatest objection to the Darwinian theories would be removed.
In fact, in this theory, as in all those which rest upongradual transmutationthe new species derives its origin from avariety, possessing a character which is at first rudimentary, but which is developedvery gradually, making some progress in each generation. The result of this is thatbetween successive individuals the only difference is that ofrace. Now, as we have seen, the fertility among races of the same species remains constant, and consequently, in the hypothesis of Darwin, as in that of Lamarck, etc., the fertile crossings would in every sense of the word constantly confuse the original and the derived species which was in process of formation. The same cause having produced the same effects since the commencement of the world, the organic world would present the greatest confusion instead of its well-known order.
Darwin, then, himself and his most enthusiastic adherents must admit that at some given moment theseracesbecame suddenly incapable of crossing with their predecessors. Whence then arises thesterilitywhich separatesspecies? When, and at what moment will the physiologicalbondbe broken, which unites the original species with its modified descendants, even when this modification is carried as far as the ordinary ox and the niata? What will be the determining cause of this great fact which obtains through the whole economy of the organic kingdom?
In his work upon theVariation of Animals and Plants, Darwin replies: “Since species do not owe their mutual sterility to the accumulative action of natural selection, and a great number of considerations show us that they do not owe it to a creative act, we ought to admit that it has been produced incidentally during their gradual formation, and is connected with some unknown modification of their organisation.”
We have seen that, in the last editions of theOrigin of Species, he refuses to admit that fertility among mongrels is general, taking his stand upon ourignoranceon the subject of crossings between wildvarieties(races).
Thus, in order to admit the physiological transmutation of race into species, a fact which is contrary to all positive facts, Darwin and his followers reject the secular results of experience and observation, and substitute in their place apossible accident, and theunknown.
The Darwinian theory relies entirely upon the possibility of this transmutation. We see upon what data the hypothesis of this possibility rests. Now, in atruly liberal spirit, I ask everyunprejudicedman, however little he may be conversant with science, the question, is it upon such foundations that a general theory in physics or chemistry would be founded?
V. Moreover, the argument, of which we have just seen an example, may be found in every page of Darwinian writings. Whether a fundamental question, such as we have just been examining, or a minor problem, as the transmutation of the tomtit into the nuthatch, is under discussion,possibility,chance, andpersonal convictionare invariably adduced as convincing reasons. Is modern science established upon such foundations?
Darwin and his disciples wish that even our ignorance on the subject of certain phenomena should be considered as in their favour. The question has often been argued on the ground of palæontology, and they have been asked to point out a single instance of those series which ought, according to them, to unite the parent species with its derivatives. They admit their inability; but they reply that the extinct fauna and flora have left very few remains; that we only know a small part of these ancient archives; that the facts which favour their doctrine are doubtless buried under the waves with submerged continents, etc. “This manner of treating the question,” Darwin concludes, “diminishes the difficulties considerably, if it does not cause them to disappear entirely.”
But, I again ask the question, in what branch of human knowledge, except these obscure subjects, should we regard problems as solved, for the very reason that we possess none of the requisite knowledge for their solution?
I do not intend to reproduce here the entire examination which I have made elsewhere of the transmutation theories in general, or of Darwinism in particular. The above observations will suffice, I hope, to show why I could not accepteven the most seductive of these theories. In certain points they agree with certain general facts and give an explanation of a certain number of phenomena. But all without exception attain this result only by the aid of hypotheses which are in flagrant contradiction with other general facts, quite as fundamental as those which they explain. In particular, all these doctrines are based upon a gradual and progressive derivation, upon the confusion of race and species. Consequently they ignore an unquestionable physiological fact; they are entirely in opposition with another fact, which follows from the first, and is conspicuous from every point of view, the isolation, namely, of specific groups from the earliest ages of the world, and the maintenance of organic order through all the revolutions of the globe.
Such are my reasons for refusing my adherence to Darwin’s theories.
VII. The theory of the English naturalist is certainly the most vigorous effort which has been made to trace back the origin of the organic world by processes analogous to those which we have discovered in the genesis of the inorganic world, that is to say, in only having recourse to secondary causes. He has failed, as we see, like Lamarck. These eminent men will be succeeded by others who will attempt the solution of the same problem. Will they be more fortunate?
No one is less inclined than I am to place any limit upon the extension of human knowledge. Yet the extension of our scientific knowledge, in the widest sense of the term, is always subordinate to certain conditions. The most attentive examination, even of a human work, will never teach us anything of theprocesseswhich have permitted its realisation. The cleverest watchmaker, if he has not followed studies perfectly foreign to his vocation, will know nothing of the origin of iron, of its transformation into steel, of the rolling and tempering of a main spring. The minutest study of that metallic ribbon which he knows so well, will tell him nothing of its origin, nothing of the process of its fabrication.To know more he must leave his shop and visit the furnaces, the forges, and the rolling mills.
In the works of nature it is the same. With nature as well as with ourselves, the phenomena whichproduceare very different from those whichpreserve, and from those displayed in theobject produced.
The most complete anatomical and physiological study of an animal or of a full-grown plant will certainly teach us nothing about the metamorphoses of the microscopic cell from which sprang the dog, the elephant, and man himself.
Now hitherto we have only directed our attention to species already formed. We can therefore learn nothing more relative to their mode of production.
But we know that theunknown causewhich has given birth to extinct and living species has been manifested at different times and intermittingly upon the surface of the globe. Nothing authorises us to suppose that it is exhausted. Although it appears to have generally acted at times which correspond to great geological movements, it is not impossible that it may be at work on some point of the earth even at this epoch of relatively profound rest. If this is the case, perhaps some happy chance will throw a little light upon the great mystery of organic origins. But until experience and observation have taught us something, all who wish to remain faithful to true science, will accept the existence and succession of species as a primordial fact. He will apply to all what Darwin applies to his singleprototype; and, in order to explain what is still inexplicable, he will not sacrifice to hypotheses, however ingenious they may be, the exact and positive knowledge which has been won by nearly two centuries of work.