Evolution Social and Organic

by Arthur M. Lewis

This instance is moderate compared with multitudes of others. The question then arises as to why, of such a numerous progeny, only a sufficient number reach adult stage as will replace the parent stock so that population remains practically stationary.

Here Darwin became indebted to Dr. Malthus who, but for that indebtedness would have been forgotten ere this. In his “Essay on Population” Malthus points out various “checks” to the increase of population. His main theory was that the population tends to increase more rapidly than the food supply. The Reverend Doctor, having begotten twelve children of his own, felt “called” to point out to British parents the desirability and even necessity of limiting their families in the interest of society. Malthus applied his theory to human society where it is palpably false. Darwin transferred it to the natural world where it proved to be a great truth. The obvious explanation of this paradox is: that man, by agriculture and industry, can increase his food supply to a greater proportion than any probable or even possible increase of population. Animals cannot; their food supply is beyond their control; they have no power to artificially increase the supply. This difference totally destroyed the value of Malthus’ book as a treatise on political economy. His immortality is assured solely because he accidentally contributed a link to Darwin’s chain.

And now Darwin has travelled on his great journey thus far: Animals propagate enormously but their population generally does not increase. The main reason for this, though there are others, is, that their number is limited by the amount of food available. Therefore, if two parents produce ten thousand only two or three individuals will reach maturity: the rest will perish. The remainder of the problem, which still remained for Darwin to solve, was: first, is there any law which determines which shall survive and which shall be destroyed; and second, if there is such a law, will that law explain and thus, at the same time, prove, the origin of new species? It is precisely because Darwin solved both points of this tremendous problem with a clear and irrefutable affirmative that he occupies the foremost place in the annals of science.

Professor John Fiske said: “There is one thing which a man of original scientific or philosophical genius in a rightly ordered world should never be called upon to do. He should never be called upon to earn a living; for that is a wretched waste of energy, in which the highest intellectual power is sure to suffer serious detriment, and runs the risk of being frittered away into hopeless ruin.”

Whether Fiske was right or wrong the only pertinent point here is that Darwin was spared that necessity.

To his great task he brought a patience that is almost without parallel. One of his biographers, Grant Allen, tells us that: “His uncle and father-in-law, Josiah Wedgwood, suggested to him that the apparent sinking of stones on the surface might really be due to earthworm castings. So, as soon as he had some land of his own to experiment upon, he began in 1842, to spread broken chalk over a field at Down, in which, twenty-nine years later in 1871, a trench was dug to test the results. “What other naturalist,” asks Allen, ever waited so long and so patiently to discover the upshot of a single experiment? Is it wonderful that a man who worked like that should succeed, not by faith but by logical power, in removing mountains?”

Darwin studied domestic animals. He observed how many, and how widely different, races there are of horses, dogs, swine, poultry in general and pigeons in particular. In each instance the many varieties are derived from an original common stock, as domestic fowls from the Indian jungle fowl, and pigeons from the old-world rock-dove.

“Derived,” but how—by what process? In the case of domestic creatures this was not difficult to answer. It is accomplished by breeders “selecting” the individuals to be bred from. In the case of pigeons, which Darwin laid particular stress on the fancier seemed to be able to obtain almost any kind of a bird by selecting as parents those pigeons which had the desired characteristics developed to the most pronounced degree, and then again selecting in the same way from their progeny. In this way were produced birds so different from each other and their ancestors as the tumbler, the fantail, the pouter, and about a hundred and fifty other varieties. The same with horses. If the breeder desired draught horses, he selected for parents those animals with massive shoulders and sturdy limbs. When a racer wins a “classic” race, it is at once sent to the stud-farm. Although in the zenith of its powers it races no more; it is “selected” for another and more important role—the reproduction and, it is hoped, the accentuation of the characteristics which enabled it to outrun its competitors.

All this impressed on Darwin’s mind the importance of the word “selection,” which appears in the title of his theory and the subtitle of his epoch-making book. Could it be possible that nature contained some principle or combination of principles, which performed among wild animals a part analogous to that of the breeder, among domestic animals? Darwin discovered that this is precisely what takes place. His famous theory may be formulated under the three following heads:

(1) Heredity.

(2) Variation.

(3) The struggle for existence, with its resultant, survival of the fittest.