"Darwinism"
by Chas. H. Williamson
Found in The McMicken Review, Vol. 6, No. 7, October 1892
One of the most memorable years within the memory of men now living was that in which was given forth to the world that principle which is currently known as “Darwinism.” The great principle of natural selection, as enunciated by Charles Robert Darwin, inaugurated a revolution in natural science, the progress of which has been astonishingly rapid and complete. Not alone has this idea of a progressive unfolding permeated the domain on natural science, but art, poetry, history, economics, and politics have all been discussed, of late years, from this standpoint.
The theory rests on two most important classes of facts, applying to all living organisms. First, a severe and constant struggle for existence is the direct outcome of the rapid multiplication of individuals. Then the question arises, “Why do some live rather than others” “Is not out planet large enough for all?” And the answer given is, “The fittest will survive,” the fittest being “those which are superior in the special qualities on which safety depends.”
The question of heredity plays an important part in this theory. It is a matter of common knowledge that the average quality of domestic plants and animals may be greatly improved by always selecting the best seeds to sow, or the finest and best formed animals to breed from. Still more is this noticeable in man. “How much he looks like his father!” is an expression with which we are familiar, and of whose truth we are convinced. That the struggle for existence is incredibly great may be readily demonstrated. It is known to everyone that a few weeds left to grow in a garden will soon displace all flowers, while they, in turn, will soon be crowded out by other species of weeds. Thus in the course of a few years the entire plant life will be changed. A freshly dug piece of ground was found by Darwin to contain357 seedlings of weeds and other plants, of which less than 295 were destroyed by slugs and insects. The severity of the struggle may be further indicated by calculating the great powers of increase in animals. Columbus, in this second voyage to St. Domingo, left a few black cattle, and yet these animals, which breed comparatively slowly, had increased to such an extent that twenty-seven years later herds from four to eight thousand were not uncommon. A few years after the introduction of rabbit skins into New Zealand no less than seven million skins were exported in a single year. That great fertility if not necessarily essential to rapid increase is shown by the passenger pigeon and the fulmar petrel, two very abundant species, the former of which lays but two eggs and the latter one. As regards the ethical aspect of the struggle for existence, Darwin concludes his chapter on that subject thus: “When we reflect on this struggle we may console ourselves with the full belief that the war of nature in not incessant, that no fear is felt, that death is generally prompt, and that the vigorous, the healthy and the happy survive and multiply.”
The foundation of the Darwinian theory, as has been said, rests upon the variability of species. It has been held that the wide variations of the domestic animals are due to their unnatural surroundings. Facts show this to be erroneous, since animals and plants in a state of nature show great and important variations. Among the lowest animals this is illustrated by the following remark of Carpenter: “The range of variation is so great among the Foraminifera as to include not merely those differential characteristics which have been accounted specific, but also those upon which the greater part of the genera are founded, and even in some instances those of its orders.” In a higher class (a species of insects), a competent authority says: “This species is so variable that it is difficult to find two examples exactly alike.” Among still higher classes, lizards, birds, mammals, many accurate numerical data can be cited to prove a remarkable and extensive variability.
Among domestic animals the generality of variation is amply proven by the experience of breeders, and in this plant world artificial selection has resulted in a complete metamorphosis of the fruits of certain plants, while the flower remains practically constant. This goes to prove that mere cultivation, of even variation of soil and climate, is of little avail unless selection be present to preserve and accumulate the small variations which constantly occur. In this last idea is shown the great power of selection, whether natural or artificial; it becomes important only by its cumulative power. The effect of the struggle for existence, if we assume the conditions to remain unchanged, will be, in a word, to prevent any possible deterioration. Every species will be kept in the most perfect harmony with the conditions of its existence, and thus that health, beauty and enjoyment will be brought about which leads the average observer to suppose that peace and quietude is the order of nature.
The very same process, however, which has thus far kept an animal or plant in the state of greatest perfection, will, if we materially change the conditions, suffice to change the habitus or structure so that they will accord with those changed conditions. Great physical changes, e.g. the elevation of marshes into plateaux and the subsidence of elevation of land connecting continents, would, of course, lead to the extinction of many species and a very great modification of others.
Great divergence in character, as well as in form, may be brought about. This is well illustrated in certain insects in the Island of Madeira, which are almost wingless, while on the continent the same species have well-developed wings. The explanation is as follows: Madeira, whose fertile land lies largely on the coast, is much exposed to oceanic tempests, Hence, wings proving a danger, the shorter-winged individuals would naturally survive these tempests, and the constant preservation of these led, in time to the production of a wingless species. That this is the true explanation, and is not due to any general tendency to abortion of wings in the island, is shown by the fact that some of the flower-frequenting insects, to whom wings, of course, are essential, possess wings even more developed than the same species on the mainland. A strong collateral prop is furnished by the fact that many large and common families are entirely absent in the island. And why? Because the abortion of wings in those cases was accomplished too slowly to prevent the destruction of the insects before they could well establish themselves.
The divergence in character has a double purpose, and leads to a double end. It enables a species, in the process of extinction by enemies, to save itself by taking up new habits or by filling a vacant place in nature. Again (which is less obvious), the greater the diversity of organic life inhabiting a place, the greater is the amount of life which that place can sustain. Hence the long duration of the struggle for existence leads to greater diversity in the area in question. Darwin found a small plot of ground, only three by four feet in size, to contain twenty species of plants, belonging to no less than eighteen species and eight orders.
A curious, though quite obvious, result of the general action of the principle of selection is, that the most closely allied species inhabit countries widely separated. Thus, the closest allies of the European plover are found in North America and Eastern Asia, while the type nearest akin to the European jay is found in Japan.
Among domesticated animals and cultivated plants it is found that a variation of use to the organism at one stage of life occurs in its progeny at the same stage, and that selection may accumulate and perpetuate this variation without modifying other parts. Thus, the silkworm cocoon, the eggs of our poultry, shoots of young vegetables, etc., have been, for man’s purposes, greatly improved. This explains the adaptation of many seeds to different modes of dissemination. Among animals, it explains why certain insects have strong jaws to break the cocoon, and unhatched birds have a hard-tipped beak to break open the egg-shell.
The question naturally arises, “Why, if selection is operative, do the lowest forms of life continue to exist?” And the answer is, they have few or no competitors, and they fill a place in the economy of nature which can not be filled with more highly organized forms. Hence, a motive power being wanting, modification does not take place. As we get higher in the scale, the great gaps separating the mammals, birds, reptiles and fishes, and the complete isolation of the lowest forms of these, indicate a very great and oft-repeated extinction of lower by higher forms.
One of the strongest objections raised against the Darwinian theory was that the variability of organisms occurs in infinitesimal proportions, singly and at considerable intervals. Munerical data have, however, shown this supposition to be erroneous. Another and yet more potent objection was that it is inconceivable how the first beginnings of important organs, such as eyes, ears, wings, the various glands, came about. To this we can only answer, “Beginnings are beyond the pale of science.” Given the starting-point, as seen in the pigment spot of our lowest existing animals, and the steps are readily traceable. At first a simple nerve and a few pigment cells, then a cavity containing a gelatinous mass of a convex form, the first rudiment of the lens; and so on, many stages having of necessity become extinct, owing to the enormous advantage gained by even a small increase in perfection in so important an organ as the eye. The rotation of the eyes of the flat fish is a more difficult, and yet more fully explained, example.
Again, it has been objected that very many useless characters are perfectly permanent and stable. This is, however, to be regarded as due to our yet far from complete knowledge. The great difference in the development of the ears in certain rodents and the tail in larger mammals, the difference in markings in all classes of animals, protective mimicry, and many others, have no all been well explained, and it is probable that all will be explained with our increasing knowledge.
One of the most successful applications of Darwinism to the interpretation of organic phenomena has been that which relates to the colors of animals and plants. The coloring of organisms, considered in pre-Darwinian times as of little importance, was shown by that great naturalist to be a well-marked, conspicuous and stable character, and that, furthermore, it conforms perfectly to the laws of utility as enunciated by him. The Arctic regions afford striking examples of the relations between animal coloration and the general environment. For example, the polar bear, the American polar hare, the snowy owl and the Greenland falcon, all of which have habitats where constant snow prevails, preserve their white color throughout the year; while the Arctic fox, the ermine, and the ptarmigan, which inhabit regions free from snow in summer, retain their white color in winter only. That this is due to selection, and not some chemical action on the skin or some reflex action through vision, is proven by the fact that the raven, a true Arctic bird, retains its black color throughout the year. And the reason is the more obvious when we remember that the raven is a carrion feeder, and has no need for concealment.
Protective mimicry may be regarded as merely an exceptional form of protective resemblance. We may easily conceive how different species in the same group of organisms obtain their protection in different ways. It is found that all cases of protective mimicry occur under quite different conditions, which are: First, that the imitative species occur in the same area and occupy the very same station as the imitated. Second, that the imitators are always more defenceless. Third, that the imitators are always less numerous in individuals. Fourth, that the imitators differ from the bulk of their allies. And lastly, that the imitation, however minute, is external and visible only, never extending to internal character or to such as do not affect the external appearance.
Darwin’s theory of female choice being incompetent to account for the brilliant coloration of higher animals, the preponderance of this in the male, and its display at certain definite periods, the theory which seems to be most in accordance with the facts is in brief this: The fundamental colors of animals are largely protective. In the long course of development, other modes of protection than concealment by harmony of color arose, and thus gave full sway to the development of color due to complex chemical composition. The colors thus produced, modified again and again by natural selection, gradually reached the wonderful development of which we have now so many examples.
Lastly may be considered the applicability of this theory to man. Man’s physical structure is no exception to the law of descent with modification, but in fact is a most excellent example of it. On the other hand, his intellectual and moral nature, while continuously and progressively developed from animal to man, is not developed by natural selection, but finds its origin in the unseen world of spirit.
