At one time it was very confidently asserted, by many eminent physiologists, that the differences between various branches of the human race were so great, that it was impossible that all should have descended from the same original stock. Probably this opinion is still maintained in some quarters, but of late years views of a diametrically opposite character have been brought forward, and very ably advocated. In proportion as these views are admitted to have in them an element of truth, the importance of the older objection is diminished. It will therefore be unnecessary to dwell upon it. This new view is, that not only all branches of the human race, but all living beings now existing, or that have ever existed on the face of the earth, are descended by the process of "evolution," carried on under what are designated as "natural laws" from some one variety, or small number of varieties of living creatures of the lowest type.
This theory, like that of Laplace, had its origin among the French Academicians, at the close of the last century. Its author was La Marck. According to his view the simplest form of animal life, the "monad," was spontaneously developed by some unknown process. From this monad higher forms of animal life were produced, and the course of development was continued till it finally culminated in man. But it does not appear that La Marck suggested any means by which the various stages of development were brought about, and the view attracted little attention. Some thirty years ago it was revived by an anonymous writer, in a work called "Vestiges of Creation." In this work the idea of spontaneous generation was repudiated. The original monad was supposed to have derived its existence from an act of Creative Power, and to have been then left to work out its own development, by virtue of powers originally implanted in it. All its variations and advances were supposed to be the result of the will and efforts of the creature acting through many generations. Thus the desire and attempt to walk ended in the development of legs, while wings were the final result of its efforts to fly. It was felt, however, that this was by no means a satisfactory account of the state of things, and so the work, though it produced a great sensation at the time, has now been almost entirely forgotten.
Latterly, however, the theory has found a far more able advocate in the person of Mr. Darwin, with whose name it has been popularly identified. By his indefatigable labours a vast variety of facts have been collected and skilfully arranged, to show that all the varieties of life may be satisfactorily accounted for by the continued action, through a long course of ages, of certain natural causes, with the results of which we are familiar, and of which intentional use is continually made by man. Mr. Darwin does not deny the existence of a Creator, but the tendency of his arguments is to prove that His interference was limited to the single act of original Creation; and that from the moment of its creation the world has been a sort of automatic machine, producing its results without any interference from any higher power.
The theory taken as a whole comes into contact with the Mosaic
Record in three points:—
1. As it assumes the possibility that life may be self-originated.
2. As it indicates a mode of procedure different from that given by Moses.
3. As it requires unlimited time.
Of these the last is already disposed of, when the narrative is shown to be capable of an interpretation in accordance with it. The first requires only a brief notice; but the second must be carefully investigated, to separate ascertained truth from inferences which have no sufficient foundation.
The theory of spontaneous generation rests almost entirely upon assumptions. Its only semblance of support from facts is derived from certain experiments of a very unsatisfactory character, which are said to have resulted in the production of some of the lowest forms of animal life. These experiments have been by no means uniformly successful. One or two experimenters have thought that they have succeeded, but not uniformly, while the same process, repeated by men whose scientific and manipulative powers are universally recognized, has never once resulted in any seeming development of life. Even if, however, they had been uniformly successful, there would have been great reason to doubt whether the apparent success was not really a failure—a failure in the precautions necessary to exclude all germs of life from the matter experimented upon. For the lower forms of life are excessively minute; and their germs—eggs, seeds, or spores—must be far smaller. It is known that these are constantly floating in the atmosphere, though, owing to their extreme minuteness, the fact can only be ascertained by the most skilful investigation. And the lower forms of animalcules have a singular tenacity of life; they can pass unharmed through processes which would be fatal to creatures of higher organization. One variety is known to survive entire desiccation; another lives upon strychnine; others bear without injury great extremes of heat and cold; and if this is the case with the mature creatures, it is probable that the germ possesses still stronger powers of vitality. If one acarus can live upon strychnine, then it is not impossible that mineral acids should be harmless to others; the germs might be carried through sulphuric acid in air without coming into contact with the acid, as air would pass through in bubbles, in the centre of which they might be suspended; or if like the diatomaceae, they were coated with silex, they might come into contact with it and resist its action. Thus one of the precautions commonly taken is not certain in its action, and the same might be shown to be true of the others. The theory of spontaneous generation is, in fact, generally repudiated by Evolutionists, and cannot therefore be taken as a starting-point.
We come then to the theory of Evolution with which Mr. Darwin's name is associated. This theory asserts that all the varieties of animal life now existing on the earth, however widely they may differ from each other, are in reality derived from one, or a very few original types; and that in this general statement the human race is to be included. This theory rests upon the following admitted facts.