And, in the view of the facts of geology, it follows that all living animals and plants are the lineal descendants of those which lived long before the Silurian epoch.
Here is a plain issue, and one, as has been said, to be discussed without prejudice. That the innumerable[{207}] forms of organic life should thus have been genetically derived one from another, is no more difficult to conceive than that they should have come into existence at all. Moreover, it appears to our minds almost a first principle that natural law must suffice to account for the phenomena of nature from beginning to end, and that any system is self-condemned which finds anywhere in these phenomena evidence of a non-natural, or supernatural, interposition. Has not such a theologian as Suarez, following St. Augustine, laid it down as an axiom[243] that God does not directly interfere with the operations of Nature, when He can effect His purposes through natural causes? Undoubtedly, too, it is difficult for our minds to imagine in what way, except through genetic evolution, the successive production of more and more developed types could be effected.
But, as has before been observed, what seems to us probable is not therefore proved to be true. What we want are facts, and by facts we must be ready to abide. At the same time, it is not very easy to understand the supreme importance which evolutionists generally appear to attach to the descent of all living creatures from some one original, and their abhorrence of the idea that the power, whatever it was, which first produced life, may have operated repeatedly, at different epochs, to repeat the production. It seems to be assumed that this must imply "miracle"[{208}] and interruption of the continuity of Nature, to admit which is irrational and unscientific. But since life did unquestionably once originate somehow, which Science makes no attempt to deny, why should it be so improper to suppose that it originated more than once, at various times and in various forms, and that, consequently, genetic descent with modification, or "Evolution," is not the explanation of typic development? As Sir J. W. Dawson writes[244] concerning the oyster tribe, whereof two species are found in the Coal Measures (one European and the other American), and a continuous succession of species ever since:
All these species may have proceeded from one origin, by descent with modification, or, on the other hand, the same causes which led to their origination in the Carboniferous may have operated again and again.
It must, however, be remembered that, if the theory of genetic descent with accumulation of minute modifications be the true explanation of the production of new forms, it necessarily follows, that could a complete record be forthcoming of the ancestry of any actual species, there would be found in that pedigree no distinction of species or genera, for no sharply marked lines of limitation would be discoverable. It would be like the case of a man who had been photographed every hour of his life from birth to old age;—immense though the difference[{209}] might be between the two extremes, the gradations of change would at all points pass as imperceptibly into one another as do the phases of the moon. This consideration is both fundamental and obvious, yet it would seem to be almost universally ignored. It appears to be thought that, in order to demonstrate the fact of evolution, all that is needed is to find a form here and there, in some sense intermediate between others,—like the reptilian birds already mentioned. This would imply that the course of Evolution must be like that of an army, making long marches from point to point, and traceable only by the remains of its camp-fires: whereas it should be as that of a glacier continuously creeping on, and leaving its tracks at one point as much as another. What are wanted, therefore, as evidence for Evolution, are not isolated specific forms uniting some characteristics of those which they are supposed to connect,—as Nelson's men-of-war form a stepping-stone between the vessels of the Norsemen and the ironclads of the present day,—but a series sufficient to show, or at least to indicate, that all changes have been gradual and insensible, without the introduction at any point of a new element. To pursue the illustration, such a new element would be gunpowder or steam in the evolution of the battle-ship, for by no mere development could bows or javelins produce a cannon, or sailing ships a steamboat.
Therefore, in proportion as the geological record approaches completeness, its testimony,—if it is[{210}] to be in favour of Evolution—must tend more and more in this direction, and unless, in some instance at least, clear evidence be discoverable of the melting of one form into another, it cannot possibly be said that we have sufficient proof that such a process ever occurred. Mere graduated resemblance of isolated forms does not necessarily imply such transmutation, as we see for example in the methodical progression of shape, exhibited by various crystals, and even more remarkably in the affinities which we can recognize among what we know as elementary substances.
There is another important point to be borne in mind. According to the teaching of Evolutionists such as Darwin or Haeckel,[245] every Species has originated from a single ancestor,—or, as they should rather say, from a single pair.
If this were so, it would necessarily follow that every new form, originating in some particular spot of earth, would very gradually spread thence to other regions, fighting its way along. As Mr. Darwin acknowledges,[246] "The development by this[{211}] means (i.e. Natural Selection) of a group of forms, all of which are descended from some one progenitor, must have been an extremely slow process; and the progenitors must have lived long before their modified descendants."
Of this gradual spread of new types there should, at least in some cases, be some palæontological evidence.
It is likewise by no means easy to understand how species thus generated could stand solitary and isolated from kindred forms in the records of the earth. The pair of individuals which started a new persistent group,—its members all stamped with the same specific characters, while all around were in a state of flux and divergence,—differed from their immediate ancestors, as we have seen, only infinitesimally. They can have differed no more from many of their contemporaries, for all the lines of descent must ramify afresh in each generation, and so form a web rather than anything like a line. It is not very easy to understand how a pair here and there struck root and founded a species, while the thousands which jostled them round about failed to do so, for the others which survived longest must be supposed to have resembled them most nearly, and therefore to have participated in their advantages. At least, we should expect to find around them the débris of the multitude they vanquished in the struggle for existence.