The inorganic passes into the organic as night passes into day. Where does one end and the other begin? No man can tell. There is no beginning and no ending of either, and yet night comes and goes and day comes and goes—a constant becoming and a constant ending. We are probably in the midday of the life of the globe—life huge and rank and riotous—the youth of life has passed, life more sedate and aspiring and spiritual has come. The gigantic has gone or is going, the huge monsters of the sea and of the land have had their day, man appears at the end of the series of lesser but more complete forms.
Many intelligent persons who have been rocked in the cradle of the old creeds still look upon evolution as a godless doctrine and accuse it of vulgarizing high and sacred things. This state of mind can only be slowly outgrown by familiarizing ourselves with the processes of nature or of the creative energy in the world of life and matter about us; with our own origin in the low fishlike or apelike creature in the maternal womb; with the development of every plant, tree, and animal from a microscopic germ; with the unbroken sequence of natural law; with the waste, the delays, the pains, the failures on every hand; with the impersonal and the impartial character of all the physical forces; with the transformations and metamorphoses that marked the course of animal life; and, above all, with the thought that evolution is not self-caused or in any true sense a cause in itself, but the instrument or plan of the power that works in and through all things. The ways of God in all these details are past finding out, but science watches the unfolding of a bud, the development of a grain of wheat, the growth of the human embryo, the succession of life-forms upon the globe as revealed in the records of the stratified rocks, or observes in the heavens the condensation of nebulous matter into suns and systems, and it says this is one of his ways. Evolution—an endless unfolding and transformation. "Urge and urge and urge," says Whitman (I love to repeat this saying; it is so significant), "always the procreant urge of the world." Always the labor and travail pains of the universe to bring forth higher forms; always struggle and pain and failure and death, but always a new birth and an upward reach.
Strike out the element of time and we see evolution as the great prestidigitator of the biologic ages. The creative energy manipulates a fish and it turns into a reptile; it covers a mollusk as with a vapor and behold, a backboned creature instead! Now we see a little creature no larger than a fox and when we look again, behold the horse; a wolf or some kindred animal is plunged into the water, and behold, the seal! Some small creature of the lemur kind is covered with a capacious hand, and we look again, and behold man! We have only to minimize time and minimize space to see the impossible happening all about us or to see the Mosaic account of creation repeated; we have only the clay and water to begin with, when, presto! behold what we have now! We see the rocks covered with verdure, the mountains vanishing into plains, the valleys changing into hills or the plains changing into mountains, tropic lands covered with ice and snow.
Lord Salisbury thought he had discredited natural selection, which is one of the feet upon which evolution goes, when he charged that no one had ever seen it at work. We have not seen it at work because our little span of life is too short. Only the palaeontologist traces in the records of the rocks the footsteps of this god of change. And rarely if ever does he find a continuous and complete record—only a footprint here and there, but he sees the direction in which they are going and many of the places where the traveler tarried. The palaeontologist, that detective of the rocks, works up his case with the same thoroughness and caution and the same power of observation as does the detective in human affairs and with a greater sweep of scientific imagination.
An agent of evolution is the influence of the environment, but who sees the environment set its stamp upon animal life? After many generations we may see the accumulated results. In a few instances the results are rapid. Thus sheep lose their wool in tropical climates and a northern fur-bearing animal its fur. The well-being of the animal demands this change, and demands it quickly. Fish lose their sense of sight in underground streams; this loss is not so vital and it comes about much more slowly. A tropical climate sets its stamp upon the complexion and character of man, but this again is a slow process, as the same stress of necessity does not exist.
In the tendency to variation—in form, size, disposition, power, fertility—man differs from all other animals. In the same race, in the same family, we find infinitely varied types. Among the wild creatures all the individuals of a species are practically alike. We can hardly tell one fox, or one marmot, or one chipmunk, or one crow, or one hawk, or one black duck from another of the same species. Of course there are slight individual differences, but they are hardly distinguishable. Among the insects, one bee, one beetle, one ant, one butterfly seems the exact copy of every other individual of its kind. The law of variation seems practically annulled in the insect world.
It is the wide and free range of this law in the human species that has undoubtedly led to the great progress of the race. There has been no dead level—no democracy of talent—no equality of gifts, but only equality of opportunity. Men differ from one another in their mental endowments, capacities, and dispositions vastly more than do any other creatures upon the earth. This difference makes man's chances of progress so much the greater; he has so many more stakes in the game. If one type of talent fails, another type may win; if the lymphatic temperament is not a success, try the sanguine or the bilious; blue eyes and black eyes and brown eyes will win more triumphs than blue or black or brown alone. Arms or legs extra long, sight or hearing extra sharp, wit extra keen, judgment extra sure—all these things open doors to more progress. Variation gives natural selection a chance to take hold, and where the struggle for life is the most severe the changes will be the most rapid and the most radical. Without the pressure of the environment natural selection would not select. The tendency to physical variation in man is probably no greater than in other creatures, but his tendency to mental variation is enormous. He varies daily from mediocrity to genius, hence the enormous range of his chances of progress. From the first variation that started him on his way in his line of descent, variation must have been more and more active till he varied in the direction of reason, long before the dawn of history, since which time his progress has been by rapid strides—and more and more rapid till we see his leaps forward in recent times. The race owes its rapid progress to its exceptional men, its men of genius and power, and these have often been like sports or the sudden result of mutations—a man like Lincoln springing from the humblest parentage. No such extreme variations are seen in any of the lower orders. Indeed, in one's lifetime one sees but very slight variation in any of the wild or domestic creatures, less in the wild than in the domestic because they are less under the influence of that most variable of animals, man. And man's variations are mainly mental and not physical. The higher we go in the scale of powers, the greater the variation and hence the more rapid the evolution. Probably man's body has not changed radically in vast cycles of time, but his mind has developed enormously since the dawn of history.
IV
Biologists are coming more and more to recognize some unknown factor in evolution, probably some unknowable factor. The four factors of Osborn—heredity, ontogeny, environment, selection—play upon and modify endlessly the new form when it is started, but what about the original start? Whence comes this inborn momentum, this evolutionary send-off? What or who set the whole grand process going?
Bergson sees an internal psychological principle of development, hence the name of his book, "Creative Evolution." Osborn uses the word "directed." Certain characters, he says, are adaptive or suited to their purpose from the start; they do not have to be fitted to their place by natural selection. Huxley uses the word "predestined"—all the life of the globe and all the starry hosts of heaven are working out in boundless space and in endless time "their predestined course of evolution." Darwin must have had in mind the same mysterious something when he said that man had risen to the very summit of the animal scale, but not through his own exertions. Not by his own will or exertion, surely, any more than the embryo in its mother's womb develops into the full-grown child by its own exertion or than our temperaments and complexions and statures are matters of our own wills and choice. Something greater than man and before him, to which he sustains the relation that the unborn child sustains to its mother, must enter into our thought of his origin and development.