Darwinism, as popularly understood, is the theory that “men are descended from monkeys,” and in general that the higher forms of life are descended from the lower, and it is regarded as Darwin's epoch-making work and his chief merit—or fault according to the point of view—that he established the Theory of Descent. This is only half correct, and it leaves out the real point of Darwinism altogether. The Theory of Descent had its way prepared by the evolutionist ideas and the speculative nature-philosophy of Goethe, Schelling, Hegel and Oken; by the suggestions and glimmerings of the [pg 089] nature-mysticism of the romanticists; by the results of comparative anatomy and physiology; was already hinted at, at least as far as derivation of species was concerned, in the works of Linné himself; was worked out in the “zoological philosophies,” by the elder Darwin, by Lamarck, Etienne Geoffrey St. Hilaire and Buffon; was in the field long before Charles Darwin's time; was already in active conflict with the antagonistic theory of the “constancy of species,” and had its more or less decided adherents. Yet undoubtedly it was through and after Darwin that the theory grew so much more powerful and gained general acceptance.
Darwinism and Teleology.
But the essential and most characteristic importance of Darwin and his work, the reason for which he was called the Newton of biology, and which makes Darwinism at once interesting and dangerous to the religious conception of the world, is something quite special and new. It is its radical opposition to teleology. Du Bois-Reymond, in his witty lecture “Darwin versus Galiani,”[4] explains the gist of the matter. “Les dés de la nature sont pipés” (nature's dice are loaded). Nature is almost always throwing aces. She brings forth not what is meaningless and purposeless, but in great preponderance what is full of meaning and purpose. What “loaded” her dice like this? Even if the theory of descent be true, in what way does it directly [pg 090] help the purely scientific interpretation of the world? Would not this evolution from the lowest to the highest simply be a series of the most astonishing lucky throws of the dice by which in perplexing “endeavour after an aim,” the increasingly perfect, and ultimately the most perfect is produced? And, on the other hand, every individual organism, from the Amœba up to the most complex vertebrate, is, in its structure, its form, its functions, a stupendous marvel of adaptation to its end and of co-ordination of the parts to the whole, and of the whole and its parts to the functions of the organism, the functions of nutrition, self-maintenance, reproduction, maintenance of the species, and so on. How account for the adaptiveness, both general and special, without causæ finales, without intention and purposes, without guidance towards a conscious aim? How can it be explained as the necessary result solely of causæ efficientes, of blindly working causes without a definite aim? Darwinism attempts to answer this question. And its answer is: “What appears to us ‘purposeful’ and ‘perfect’ is in truth only the manifold adaptation of the forms of life to the conditions of their existence. And this adaptation is brought about solely by means of these conditions themselves. Without choice, without aim, without conscious purpose nature offers a wealth of possibilities. The conditions of existence act as a sieve. What chances to correspond to them maintains itself, gliding through the meshes of the sieve, what does not perishes.” It is an old idea of the [pg 091] naturalistic philosophies, dating from Empedocles, which Darwin worked up into the theory of “natural selection” through “the survival of the fittest” “in the struggle for existence.” Of course the assumption necessary to his idea is that the forms of life are capable of variation, and of continually offering in ceaseless flux new properties and characters to the sieve of selection, and of being raised thereby from the originally homogeneous to the heterogeneous, from the simple to the complex, from the lower to the higher. This is the theory of descent, and it is, of course, an essential part and the very foundation of Darwin's theory. But it is the doctrine of descent based upon natural selection that is Darwinism itself.
The Characteristic Features of Darwinism.
We do not propose to expound the Darwinian theory for the hundredth time; a knowledge of it must be taken for granted. We need only briefly call to mind the characteristic features and catchwords of the theory as Darwin founded it, which have also been the starting points of subsequent modifications and controversies.
All living creatures are bound together in genetic solidarity. Everything has evolved through endless deviations, gradations, and differentiations, but at the same time by a perfectly continuous process. Variation continually produced a crop of heterogeneous novelties. The struggle for existence sifted these out. Heredity [pg 092] fixed and established them. Without method or plan variations continue to occur (indefinite variations). They manifest themselves in all manner of minute changes (“fluctuating” variations). Every part, every function of an organism may be subject individually to variation and selection. The world is strictly governed by what is useful. The whole organisation as well as the individual organs and functions bear the stamp of utility, at least, they must bear it if the theory is correct. In the general continuity the transitions are always easy; there are no fundamentally distinct “types,” architectural plans, or groups of forms. Where gaps yawn the intermediate links have gone amissing. There is no fundamental difference between genus, species, and variety. Even the most complicated organ such as the eye, the most puzzling function such as the instinct of the bee, may be explained as the outcome of many more primitive stages.
The chief evidences of the theory of descent are to be found in homologies, in the correspondences of organs and functions, as revealed by comparative anatomy and physiology, in the recapitulation revealed by embryology, in the structure of parasites, in rudimentary organs and reversions to earlier stages, in the distribution of animals and plants, and in the possibility of still transforming, at least to a slight extent, one species into another, by experimental breeding.
Transformation and differentiation go on in nature as a vast, ceaseless, but blind process of selection. In [pg 093] artificial selection evolution is secured by choosing the most fit for breeding purposes; so it is secured in natural selection by the favouring and survival of those forms which are the most fit among the many unfit or less fit, which happened to be exposed to the struggle for existence, that is, to the competition for the means of subsistence, to the struggle with enemies, to hostile environment, and to dangers of every kind. The adaptation thus brought about is of a purely “passive” kind. The variations arise fortuitously out of the organism, and present themselves for selection in the struggle for existence; they are not actively acquired by means of the struggle. The secondary factors of evolution recognised are: correlation in the growth and in the development of parts, the origin of new characters through use, their disappearance through disuse (Lamarck), the transmission of characters thus acquired, the influence of environment and sexual selection.[5]