The evidence upon which the doctrine of evolution rests is too extensive and too technical to be even summarized here but it is regarded as trustworthy by most scientists.[[3]] For fifty years it has been studied, discussed, and tested by scholars with the result that educated men are now disposed to accept the doctrine so far as its main principles are concerned although they differ about various details.
It is astonishing how little we know, after all, about the beginnings of things. We do not know when or how life began upon the earth. We do not know the exact origin of man. But we do know that all forms of life and institutions have grown; they were not created in the shape we now have them. All the general laws of life which apply to plants and animals apply also to man. Alike they are born, they are nourished, they mature, and they produce descendants like themselves.
The principle of “natural selection” and the struggle for existence.
The method of evolution, according to Darwin’s theory is based upon the principle of natural selection. It is a well-known law of nature that “like begets like”, in other words that offspring resemble the parent-stock although there may be some individual differences. If it were not so, a definite species would never be perpetuated. All forms of life, moreover, reproduce themselves more or less abundantly. It is said that the progeny of a single starfish exceeds half a million per year. Even the elephants, which are the slowest breeding of all animals, produce a sufficiently numerous offspring to over-run the whole of Africa if every young elephant grew to maturity.
But nowhere does the entire progeny of any organisms, whether plants, animals, or human beings, survive to full growth. If every acorn became an oak tree, there would in time be no room for anything else on the surface of the earth. If every tadpole grew to be a frog, there would be no room for anything else in the waters of the earth. All life, however, is a struggle for existence, a relentless competition for air, sunshine, moisture, and soil on the part of plants, and for food and shelter on the part of animals. The further down we go in the scale of life the more bitter this struggle for existence becomes; small animals eat up the plants; large animals feed on the smaller ones. Higher in the scale, the struggle is not so keen, and among mankind it is the least strenuous of all.
In this struggle for existence, what plants and animals survive? The answer is that those which are best fitted to their environment continue to exist and to reproduce themselves, while those which are more poorly adapted to their environment fall out of the race and disappear. |The survival of the fittest.| In other words natural selection or the survival of the fittest was thought by Darwin to be the principle which determines the course of evolution. The unfit perish and the fit survive, everything depending upon the relative success of the organism in adapting itself to the conditions under which it is endeavoring to live. The clumsy mastodon became extinct; his bones are now relics in museums; but the horse, being fleet of foot, managed to survive. The fit organisms,—plants or animals or human beings,—have survived and have perpetuated the species. They gave to their offspring the traits or qualities which enabled themselves to survive. In that way each generation of organisms became a little better fitted to its environment than the generation which went before. This is a slow process for human beings, of course, for it takes twenty years or more to produce a new generation of men, whereas new generations of birds, reptiles, and lower animals appear every few months. The principle of natural selection, moreover, does not fully account for the form which evolution has taken. Other factors have also been at work, but scientists are not yet agreed as to their nature or importance.[[4]]
Natural selection as applied to the human race.
Now how does the human race figure in all this? Mankind has also been at all times under the necessity of adapting itself to its environment, and in the early stages of human history those who did not successfully adapt themselves went to an early grave. During century after century natural selection and the other factors strengthened the race. As the race grew stronger in intelligence, man undertook to subdue his environment rather than to be subdued by it, and in considerable measure he succeeded. He discovered the art of kindling a fire and made this element his servant in conquering the cold. He domesticated wild animals, made them provide him with milk and meat, and compelled them to carry his burdens. Step by step he mastered the natural conditions which surrounded him. This he did by his ability to work with his fellow-men. Through this power of co-operation he created group organizations—society, the state, and government.
Today the strong assist the weak.
The struggle for existence among men is not now, therefore, as it was in primitive days, a life-and-death competition for food and shelter. Individuals have come to recognize each other’s rights and to seek even their own advantage by co-operation rather than by strife. The association of individuals in the family and the community serves to preserve the weak whom a keen struggle for existence would eliminate. Our whole system of poor-relief, hospitals, and care for the defective is based upon the idea of giving a fair chance to those who otherwise would be crowded out of the struggle for existence altogether. The competition today is not so much between individuals as among groups, small or large, including competition between whole nations of men.