Some Irrelevant Questions
Among questions bearing upon it but not directly attacking it has been the discussion of the individual difference. For example, are differences due to individual experiences ever inherited? Or are only inherent differences transmissible? What rôle is played by what one might call “normal,” relatively slight differences, and what by the “sports” and abnormal births in specific change? Do species under stress, and feeding on strange food or living in unaccustomed climates, betray any exceptional tendency to produce abnormality? Have there been, so to speak, storms and riots of variation in some cases? Can differences establish themselves while outer necessity remains neutral? Can variations amounting to specific differences in colour and form arise as a sort of play of the germ plasm and be tolerated rather than selected by nature? In what manner do normal differences arise? What happens to differences in cases of hybridisation? Here are sample questions that have been the seeds of splendid work and great arguments. Some of them were already under discussion in Darwin’s time; he was a pioneer in such explorations; many ideas of his have stood the test of time, and many suggestions he threw out have been disproved. When some casual “may be” of Darwin’s is examined and set aside, it is the custom of polemical journalists to rush about and proclaim to all who may be sufficiently ill-informed to listen that Darwin is “exploded.” Such explosions of Darwin are constantly recurring like gun-fire near a garrison town, and still he remains. None of these subsidiary questions affect the stability of this main generalisation of biology, the Theory of Natural Selection.
The actual attack and testing of the Theory of Natural Selection have yielded negative results. The statement of the theory may have been made finer and exacter, that is all. And yet the conditions of its survival have been very exacting. If the theory is to stand, the whole of plant and animal life in time and space must be arranged in a certain order. It must be possible to replace classification by a genealogical tree. Every form must fall without difficulty into its proper place in that tree. If it is true that birds are descended from reptiles or men from apes, then there must be no birds before the reptiles appear, and no men before apes. The geological record is manifestly a mere fragmentary history, still for the most part unread, but, however fragmentary it is, it must be consistent. One human skull in the coal measures blows the whole theory to atoms. The passage from form to form must be explicable by intermediate types capable of maintaining themselves; there may be gaps in the record, but there must be no miraculous leaps in the story. If an animal living in the air is to be considered as a lineal descendant of some animal living in the water, then the structure of the former bit by bit and step by step must be shown to be adapted, modified, changed about from that of the latter; it must have ears for water-hearing modified for air-hearing, and its heart and breathing arrangements must be shown to be similarly changed over, and so on for all its structure. All these requirements will follow naturally from the necessities of a process of Natural Selection. They follow logically upon no other hypothesis. They are not demanded, for example, by the idea of a Creator continually interfering with and rectifying some stately, unaccountable process of “Evolution,” which seems to be Mr. Belloc’s idea—so far as he ventures to display any idea of his own—in the matter. Such things as vestigial structures and a number of odd clumsinesses in living things—many still very imperfect adaptations to an erect position, for example—become grotesque in relation to such a view. A Creator who put needless or inconvenient fish structures into the anatomy of a land animal and made the whole fauna and flora of the land a patch-up of aquatic forms of life must be not so much a Divinity as a Pedant. But it is the burthen of the whole beautiful science of comparative anatomy that the structure of animals and plants, and their succession in time, fall exactly into the conditions defined by the Theory of Natural Selection. In the most lovely and intricate detail, in a vast multitude of examples, in plants and in animals alike, this theme of the adaptation of pre-existing structure is worked out.
We should in accordance with the Theory of Natural Selection expect to find traces of the ancestral form, not only in the lay-out of the adult animal, but in every phase of its life history, and that, in fact, is just what we do find. There is no more fascinating branch of comparative anatomy than embryology. Each life cycle we discuss tends to repeat the ancestral story, and only under the stress of necessity does it undergo modification at any point. There is little toleration in the life process for unnecessary divergencies. Economies are effected by short cuts and reductions, and special fœtal structures are granted reluctantly. So that even in man we find peeping through the adaptations imposed upon the human type by its viviparous necessities, and in spite of the advantage of every economy of force, memories, for example, of the gill slits, of the fish heart and kidney, of the reptilian skull, of the mammalian tail. I mention this fact in the Outline, and upon it Mr. Belloc comments in a manner that leaves one’s doubts poised between his honesty and his intelligence. He declares, which is totally untrue, that I “repeat the old Victorian tag”—I doubt if there ever was such a tag—that the embryo “climbs up the family tree.” He puts these words in inverted commas as though I have really adopted and used them, and for the life of me it is only by straining my charity to the utmost that I can accept that this was an accident. Of course every text-book of embryology for the last forty years has made it perfectly plain, as I have stated here, that the life cycle can be and is modified at any point, and that an embryo has much more serious work in hand than reciting its family history. It betrays its ancestral origins to analysis; but that is an altogether different matter. Mr. Belloc, however, is so densely ignorant himself upon these questions that he can imagine, or think it worth while to pretend to imagine and attempt to persuade his readers by the expedient of these inverted commas, that I entertain such a view. And then follow this, which I quote that the reader may the better understand a certain occasional acerbity in my allusions to Mr. Belloc:—
“He doesn’t know that Vailleton of Montpellier has knocked the last nail into the coffin of that facile and superficial Victorian shortcut (and blind alley). He has probably never heard of Vailleton, and when he does he will suspect him for a foreigner. That is what I mean by being provincial and not abreast of one’s time.”
It is perfectly true that I have never heard of any Vailleton in biological science. Nor has anyone else. There is “no sich person.” Perhaps Mr. Belloc has not been able to read the manuscript of some adviser, or his memory may have played a trick upon him. Possibly he has in mind that eminent Victorian embryologist, Vialleton, who, so far from being the very newest thing in “European” biology, must now be getting on for seventy. He is half-way back to Haeckel, the originator of the family-tree idea, a German embryologist and not, as a matter of fact, the Victorian English Protestant Mr. Belloc supposes him to be. Possibly years and years ago some French student may have run away with the idea that embryos conscientiously repeat their phylogeny, and Professor Vialleton may have thought it well to discuss this idea in one of his books. It is not an idea I have ever entertained, much less stated, and its only interest here is that it gives Mr. Belloc a chance of showing how rudely he can set out his inaccuracies and his misconceptions.
But this is an incidental comment. I will reserve for my next section a consideration of the remarkable arguments—“crushing arguments” the enthusiastic cross-heads of his editor declare them to be—that Mr. Belloc produces against this view of life as being in a state of change under the action of Natural Selection, that I have put here before the reader.
III
MR. BELLOC AS A SPECIMEN CRITIC OF NATURAL SELECTION
The chief arguments against the Theory of Natural Selection with which Mr. Belloc has favoured us are neatly set out by him in two triads. His passion for orderly arrangement is greater than his logic, and we shall find that the second and third arguments of his second triad are substantially the same. He is rather exceptionally ignorant of modern scientific literature, and his arguments do not cover all the countervailing considerations upon which systematic observation and research work have been based—the speculations of Dr. Fairfield Osborn would have been a godsend for him—but the things he has to say are conveniently simple; they embody some prevalent misconceptions, and they will be useful in accentuating the more salient points in my account of the theory given in my second paper.
He produces first certain remarkable a priori arguments—his “three a prior arguments.” The first is beautifully absurd. It is difficult to believe it is advanced in anything but a spirit of burlesque. He says that an advantage is not an advantage. He says that an advantage does not give an advantage unless it is combined with other advantages. You will think I am misrepresenting him. Then please read this:—
“(1) The advantageous differences making for survival are not of one kind in any particular case, but of an indefinitely large number (e.g., climate getting colder needs not only warmer coat, but power to digest new food, protective colouring so as not to show dark against snow, etc., an indefinitely large number of qualities). Now the chance of all being combined (and co-ordinated) in a single individual, without design, accidentally, let alone of their thus appearing in many individuals accidentally and without design, approximates to zero.”
This is, so to speak, the short uncompleted form of the first argument. It is expanded later to a copiousness too great to admit of quotation. This expansion carries the statement right to its conclusion, that only an individual possessing all the possible differences that are advantageous at any particular time can survive. Otherwise its differences have no “survival value.” They may be advantages, but not sufficient advantages to score an advantage. I know this sounds tipsy, but there it is in black and white in Mr. Belloc’s wonderful Article V for any one to consult. It follows plainly that, except for a miracle, every species must be exterminated in every generation. I can see no other way out of it. No individual, he declares, can survive without the full set of advantageous differences, and the chance of any individual having the full set of advantageous differences, he declares after some abstruse verbal gestures, is zero. There is Mr. Belloc with his unfailing logic, his clear mathematical demonstration, and all the rest of it. There is the lucid Latin mind shining above my Nordic fog! Yet the previous generation got along without any of the set! And species do survive.
Did Mr. Belloc imagine he was saying something else? It is not for me to speculate. Helping out an antagonist in a controversy is apt to be resented. He has, I think, simply got into a muddle here, and he is not sufficiently self-critical to get out of it again. So he tries to muddle through. It is quite reasonable to say that when a species is under stress of changing conditions it is usual for the need for adaptation to be felt upon a number of points and not simply upon one, and that, since every advantage counts, the individuals with the greatest combination of advantageous differences have the best chances. But that does not alter the fact that even a single advantage is an advantage. What happens in nature is not an extermination of all who are not completely in the fashion of the new differences. That seems to be Mr. Belloc’s idea, but it is a wrong idea. What does happen is a diminution in each generation of the number of the disadvantaged in relation to the number of the advantaged. That is quite another affair. Mr. Belloc has not grasped this. His third a priori argument shows as much even more plainly than his first, and to that I shall presently come.