This is not the place to enter into any elaborate discussion as to the truth of the theory of evolution. Few will be found to deny the statement that it is a theory which does explain Nature as we see it and as we learn its history in the past, but that does not necessarily prove that it is true. St. Thomas Aquinas, dealing with the movements of the planets, makes a very important statement when he tells us, in so many words, that, though the hypothesis with which he is dealing would explain the appearances which he was seeking to explain, that does not prove that it is the true explanation, since the real answer to the riddle may be one then unknown to him. There are, however, one or two points it may be useful to consider before we leave the question.
That evolution may occur within a class seems to be quite certain. The case of the Porto Santo rabbits, one of many cited by Darwin or brought to knowledge since his time, will make clear what is meant. Porto Santo is a small island, not far from Madeira, on which a Portuguese navigator, named Zarco, let loose, somewhere about the year 1420, a doe and a recently born litter of rabbits, which we may feel quite sure belonged to one of those domestic breeds which have all been derived from the wild rabbit of Europe known to zoologists as Lepus Cuniculus. The island was a favourable spot for the rabbits, for there do not appear to have been any carnivorous beasts or birds to harry them, nor were there other land mammals competing with them for food; and, as a result, we are told that they had so far increased and multiplied in forty years as to be described as "innumerable." In four and a half centuries these rabbits had become so different from any European rabbits that Haeckel described them as a species apart, and named it Lepus Huxlei. This rabbit is much smaller than the European form, being described as more like a large rat than a rabbit. Its colour is very different from its European relatives; it has curious nocturnal habits; it is exceedingly wild and untamable. Most remarkable of all, and most conclusive as to specific difference, Mr. Bartlett, the highly skilled head keeper of the London Zoological Gardens, utterly failed to induce the two males which were brought over to those gardens to associate with or to breed with the females of various other breeds of rabbits which were repeatedly placed with them. If the history of these Porto Santo rabbits had been unknown to us, instead of being a matter as to which there can be no doubt, every naturalist would at once have accepted them as a separate species. We need not hesitate, it appears, to do so and to admit that it is a new species which has been produced within historic times and under conditions with which we are fully acquainted. It may, however, be argued, and quite fairly argued, that such a process of evolution, though definitely proved, is a very different thing from such an evolution as would permit of a common ancestry for animals so far apart, for example, as a whale and a rabbit, or perhaps even nearer in relationship, as between a lion and a seal. To discuss this further would require a dissertation on the highly involved question of species and varieties, and that is not now to be attempted. What, however, may be said is that the difficulties presented by what is called phylogeny—that is, the relationships of different classes to one another—are so great as to have led more than one man of science to proclaim his belief that evolution has been poly—and not mono—phyletic. Such is the view which has been enunciated by Father Wasmann, S.J., whose authority on a point of this kind is paramount. It has also been upheld by Professor Bateson, a man widely separated from the Jesuit in all but attachment to science. Professor Bateson summed up his belief in the text which he placed on the title-page of his first great work on Variation: the text which proclaims that there is a flesh of men, another of beasts, another of birds, another of fishes.
Darwin remained to the end of his life undecided between the two views, for he allowed his original statement as to life having been breathed into one or more forms by the Creator, to pass from edition to edition of the Origin of Species. If the polyphyletic theory be adopted, it must be said that the position of the materialist is made far more difficult than it is at present. Let us see what it means. On the materialistic hypothesis, and the same may be said of the pantheistic or any other hypothesis not theistic in nature, a certain cell came by chance to acquire the attributes of life. From this descended plants and animals of all kinds in divergent series till the edifice was crowned by man. I have elsewhere endeavoured to point out all that is involved in this assumption, which, it must be confessed, is a very large mouthful to swallow.
Let us now consider what the polyphyletic hypothesis involves. According to this view one cell accidentally developed the attributes of vegetable life; a further accident leads another cell to initiate the line of invertebrates; another that of fishes, let us say; another of mammals: the number varying according to the views of the theorist on phylogeny. Let us not forget that the cell or cells which accidentally acquired the attributes of life, had accidentally to shape themselves from dead materials into something of a character wholly unknown in the inorganic world. If one seriously considers the matter it is—so it seems to me—utterly impossible to subscribe to the accidental theory of which the immanent god—the blind god of Bergson—is a mere variant. One must agree with the late Lord Kelvin that "science positively affirms creative power ... which (she) compels us to accept as an article of belief." But what are we to say with regard to the series of repeated accidents which the polyphyletic hypothesis would seem to demand? Is it really possible that any man could bring himself to place credence in such a marvellous series of occurrences? Monophyletic or polyphyletic evolution, whichever, if either, it may have been, presents no difficulty on the creation hypothesis.
The Divine plan might have embraced either method. It is not merely revelation but ordinary reason which shows us that the wonderful things which we know, not to speak of the far more wonderful things at which we can only guess, cannot possibly be explained on any other hypothesis than that of a Free First Cause—a Creator.
FOOTNOTES:
[35] The Theory of Evolution. By William Berryman Scott. New York: The Macmillan Co.