We have first to note that in various ways the action of natural selection has been profoundly modified in the course of the development of mankind from a race of inferior creatures. One of the chief factors in the production of man was the change that occurred in the direction of the working of natural selection, whereby in the line of man's direct ancestry the variations in intelligence came to be seized upon, cherished, and enhanced, to the comparative neglect of variations in bodily structure. The physical differences between man and ape are less important than the physical differences between African and South American apes. The latter belong to different zoölogical families, but the former do not. Zoölogically, man is simply one genus in the old-world family of apes. Psychologically, he has travelled so far from apes that the distance is scarcely measurable. This transcendent contrast is primarily due to the change in the direction of the working of natural selection. The consequences of this change were numerous and far-reaching. One consequence was that gradual lengthening of the plastic period of infancy which enabled man to became a progressive creature, and organized the primeval semi-human horde into definite family groups. I have elsewhere expounded this point, and it is known as my own especial contribution to the theory of evolution.
Another associated consequence, which here more closely concerns us, was the partial stoppage of the process of natural selection in remedying unfitness. A quotation from Herbert Spencer will help us to understand this partial stoppage: "As fast as the faculties are multiplied, so fast does it become possible for the several members of a species to have various kinds of superiorities over one another. While one saves its life by higher speed, another does the like by clearer vision, another by keener scent, another by quicker hearing, another by greater strength, another by unusual power of enduring cold or hunger, another by special sagacity, another by special timidity, another by special courage.... Now ... each of these attributes, giving its possessor an extra chance of life, is likely to be transmitted to posterity. But" it is not nearly so likely to be increased by natural selection. For "if those members of the species which have but ordinary" or even deficient shares of some valuable attribute "nevertheless survive by virtue of other superiorities which they severally possess, then it is not easy to see how this particular attribute can be" enhanced in subsequent generations by natural selection.[2]
These considerations apply especially to the human race with its multitudinous capacities, and I can better explain the case by a crude and imperfect illustration than by a detailed and elaborate statement. If an individual antelope falls below the average of the herd in speed, he is sure to become food for lions, and thus the high average of speed in the herd is maintained by natural selection. But if an individual man becomes a drunkard, though his capabilities be ever so much curtailed by this vice, yet the variety of human faculty furnishes so many hooks with which to keep one's hold upon life that he may sin long and flagrantly without perishing; and if the drunkard survives, the action of natural selection in weeding out drunkenness is checked. There is thus a wide interval between the highest and lowest degrees of completeness in living that are compatible with maintenance of life. Mankind has so many other qualities beside the bad ones, which enable it to subsist and achieve progress in spite of them, that natural selection—which always works through death—cannot come into play.
Now it is because of this interval between the highest and lowest degrees of completeness of living that are compatible with the mere maintenance of life, that men can be distinguished as morally bad or morally good. In inferior animals, where there is no such interval, there is no developed morality or conscience, though in a few of the higher ones there are the germs of these things. Morality comes upon the scene when there is an alternative offered of leading better lives or worse lives. And just as up to this point the actions of the forefathers of mankind have been determined by the pursuit of pleasure and avoidance of pain, so now they begin to be practically determined by the pursuit of goodness and avoidance of evil. This rise from a bestial to a moral plane of existence involves the acquirement of the knowledge of good and evil. Conscience is generated to play a part analogous to that played by the sense of pain in the lower stages of life, and to keep us from wrong doing. To the mere love of life, which is the conservative force that keeps the whole animal world in existence, there now comes gradually to be superadded the feeling of religious aspiration, which is nothing more nor less than the yearning after the highest possible completeness of spiritual life. In the lower stages of human development this religious aspiration has as yet but an embryonic existence, and moral obligations are still but imperfectly recognized. It is only after long ages of social discipline, fraught with cruel afflictions and grinding misery, that the moral law becomes dominant and religious aspiration intense and abiding in the soul. When such a stage is reached, we have at last in man a creature different in kind from his predecessors, and fit for an everlasting life of progress, for a closer and closer communion with God in beatitude that shall endure.
Footnotes
[2] Biology, i. 454.
