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We are prone to speak of man’s emergence from the lower orders as if it were a simple thing, almost like the going from one country into another. But try to think what it means; try to think of the slow transformation, of the long, toilsome road even from the halfway house of our simian ancestors. If we do not give him the benefit of the sudden mutation theory of the origin of species, then think of the slow process, hair by hair, as it were, by which a tailed, apelike arboreal animal was transformed into a hairless, tailless, erect, tool-using, fire-using, speech-forming animal. We see in our own day in the case of the African negro, that centuries of our Northern climate have hardly any appreciable effect toward making a white man of him; nor, on the other hand, has exposure to the tropical sun had much more effect in making a negro of the white man. Probably it would take ten thousand years or more of these conditions to bleach the pigments out of the one skin and put them in the other. There is convincing proof from painting and figures found in Egypt that neither the African negro nor the Egyptian has changed in features in five thousand years.

The most marvelous thing about man’s evolution is the inborn upward impulse in some one low organism that rested not till it reached its goal in him. The mollusk remains, but some impulse went out from the mollusk that begat the fish. The fish remains, but some impulse went out from the fish that begat the amphibian. The amphibian remains, but some impulse went out from the amphibian that begat the reptile. The reptile remains, but some impulse went out from the reptile that begat the mammal; and so on up to man. Man must have had a specific line of descent. One golden thread must connect him with the lowest forms of life. And the wonder is that this golden thread was never snapped or lost through all the terrible vicissitudes of the geologic ages. But I suppose it is just as great a wonder that the line of descent of the horse, or the sheep, or the dog, or the bird, was not snapped or lost. Some impulse or tendency was latent or potential in the first unicellular life that rested not till it eventuated in each of these higher forms. Did any terrestrial or celestial calamity endanger the line of descent of any of the higher creatures? Was any form cut off in the world-wide crustal disturbances of the earth at the end of palaeozoic and mesozoic time, when so many forms of animal life appear to have been wiped out, that might in time have given birth to a kind unlike or superior to any now upon the earth? Species after species have become extinct, whole orders and families have gone out, often rather suddenly. Why we know not. Why the line of man’s descent was not cut off, who knows? It is a vain speculation. There can be little doubt that in early Tertiary times our ancestor was a small, feeble mammal, maybe of the lemur, maybe of the marsupial kind, powerless before the great carnivorous mammals of that time, and probably escaping them by his greater agility, perhaps by his arboreal habits. The ancestor of the horse was also a small creature at that time, not larger than a fox. It was not cut off; the line of descent seems complete to the horse of our day. Small beginnings seem to be the rule in all provinces of life. There is little doubt that the great animals of our day–the elephant, the whale, the lion,–all had their start in small forms. Many of these small forms have been found. But a complete series of any of the animal forms that eventuated in any of the dominant species is yet wanting. It is quite certain that the huge, the gigantic, the monstrous in animal, as in vegetable life, lies far behind us. Is it not quite certain that evolution in the life of the globe has run its course, and that it will not again bring forth reptiles or mammals of the terrible proportions of those of past geologic ages? nor ferns, nor mosses, nor as gigantic trees as those of Carboniferous times? Probably the redwoods of the Far West, the gigantic sequoias, are the last race of gigantic trees. The tide of life of the globe is undoubtedly at the full. The flood has no doubt been checked many times. The glacial periods, of which there seem to have been several in different parts of the earth, and in different geological periods, no doubt checked it when it occurred. But the tide as a whole must have steadily risen, because the progression from lower to higher forms has gone steadily forward. The lower forms have come along; Nature has left nothing behind. The radiates, the articulates, the mollusca, are still with us, but in the midst of these the higher and higher forms have been constantly appearing. The great biological tree has got its growth. Many branches and twigs have died and dropped off, and many more will do so, are doing so before our eyes, but I cannot help doubting that any new branches of importance are yet to appear–any new families or orders of birds, or fishes, or reptiles, or mammals. The horse, the stag, the sheep, the dog, the cat, as we know them, are doubtless the end of the series. One arrives at this conclusion upon general principles. Life as a whole must run its course or reach its high-water mark, the same as life in its particular phases. Man has arrived and has universal dominion; all things are put under his feet. The destiny of life upon the globe is henceforth largely in his hands. Not even he can avert the final cosmic catastrophe which physicists foresee, and which, according to Professor Lowell, the beings upon Mars are now struggling to ward off.