The process of evolution is not progress, but better adaptation to conditions of life. As man becomes fitted for social and civic life, so does the ape become fitted for life in the tree-tops. The movement of monkeys is towards “simianity,” not humanity. The movement of cat-life is towards felinity, that of the dog-races towards caninity. Each step in evolution upward or downward, whatever it may be, carries each species or type farther from the primitive stock. These steps are never retraced. For an ape to become a man he must go back to the simple characters of the simple common type from which both have sprung. These characters are shown in the ape-baby and in the human embryo in its corresponding stages. For ancestral traits lost in the adult are preserved in the young. This comes through the operation of the great force of race-memory, we call heredity.
Evidence of biology points to the descent of all mammals, of all vertebrates, of all animals, of all organic beings, from a common stock. Of all the races of animals, the anthropoid apes are nearest man. Their divergence from the same stock must be comparatively recent. Man is the nomadic, the apes the arboreal, branch of the same great family.
Evolution does not teach that all or any living forms are tending towards humanity. It does not teach, as in Bishop Wilberforce’s burlesque, “that every favorable variety of the turnip is tending to become man.” It is not true that evolutionists expect to find, as Dr. Seelye has affirmed, “the growth of the highest alga into a zoöphyte, a phenomenon for which sharp eyes have sought, and which is not only natural but inevitable on the Darwinian hypothesis, and whose discovery would make the fame of any observer.”
It is no wonder that a clear thinker should have rejected “the Darwinian hypothesis,” when stated in such terms as this. The line of junction in evolution is always at the bottom. It is the lowest mammals which approach the lowest reptiles. It is the lower types of plants which approach the lower types of animals. It would be the lowest alga, to use Dr. Seelye’s illustration, which would be transmutable into the lowest zoöphyte. It is the unspecialized, undifferentiated type from which branches diverge in different ways. Humanity is not the “goal of evolution,” not even that of human evolution. There will be no second “creation of man,” except from man’s own loins. There will not be a second Anglo-Saxon race, unless it has the old Anglo-Saxon blood in its veins.
Adaptation by divergence—for the most part by slow stages—is the movement of evolution. While occasional leaps or sudden changes occur in the process, they are by no means the rule. In most cases of “saltatory evolution,” the suddenness is in appearance only. It comes from our inability to trace the intermediate stages. When an epoch-making character is acquired, as the wings of a bird or the brain of man, the process of readjustment of other characters goes on with greatly increased rapidity. But this rapidity of evolution is along the same lines as the slower processes. Radical changes from generation to generation never occur. We do not expect to find birds arising from a “flying-fish in the air, whose scales are disporting into feathers.” A flying-fish is no more of the nature of a bird than any other fish is. A cow will never give birth to a horse, nor a horse to a cow. The slow operation of existing causes is the central fact of organic evolution, as it is of the evolution of mountains and valleys. Seasons change as the relations which produce them change. But midsummer never gives way to midwinter in an instant. Nor does the child in an instant become a man, though in some periods of growth epoch-marking causes may make development more rapid. Life is conservative. The law of heredity is the expression of its conservatism. It changes slowly, but it must constantly change, and all change is by necessity divergence.
There is in nature no single “law of progress,” nor is progress in any group a necessity regardless of conditions. That which we call progress rests simply on the survival of the better adapted, their survival being accompanied by their reproduction. Those that live repeat themselves. The “innate tendency towards progression” of the early evolutionists is a philosophic myth. Progress and degeneration are alike the resultants of the various forces at work from generation to generation on and within a race or species. The same forces which bring progress to a group under one set of conditions will bring degradation under another. In their essence the factors of evolution are no more laws of progress than the attraction of gravitation is. Cosmic order comes from gravitation. Organic order comes from the factors of evolution. Evolution is simply orderly change.
Evolution is not Spontaneous Generation. There is no necessary connection between the one theory and the other. Spontaneous generation, or birth without parentage, on the part of small or useless creatures was accepted in early times without question. As men began to observe these animals more carefully, the fact of their spontaneous generation was doubted. A great step was made when it was found that to screen meat from flies would protect it from maggots. A greater step came in our own time when it was proved that to screen infusions from air dust is to protect them from putrefaction or fermentation. Fermentation is “life without air.” It is the decomposition of sugar by minute creatures who disintegrate it in their life processes. Putrefaction and decay are also the same in nature. There is literal truth in Carlyle’s statement that there is still force in a fallen leaf, “else how could it rot?” It is the force of the minute organisms hidden in the leaf, and whose life is the leaf’s decay. The decay and death of men from contagious diseases is known to be due to life processes of minute organisms, as is the gangrene which follows unskilful surgery. The study of the “fauna and flora” within living organisms has now become a science of itself, demanding the greatest care in observation and the most complete of appliances. “Omne vivum ex vivo,” “all life from life,” was an aphorism of the naturalists of a century or two ago. It was to them a new and broad generalization. It has not yet been set aside. The classic experiments of Tyndall show that this law applies to all creatures we have yet recognized or classified. As far as science can tell, spontaneous generation is still a myth, having no basis in observation, no warrant in experiment. It remains as a pure deduction from the philosophical conception of Monism, incapable of proof, insusceptible of refutation. The argument for it is chiefly this: Life exists on a globe once lifeless. How did life begin? If not through spontaneous generation, how did it come? Must it not have been by the operation of those laws and forces which through all time change lifeless into living matter? Very likely, but we do not know. We know nothing whatever of such laws and forces, and we gain nothing by veiling our ignorance under a philosophical necessity.
Moreover, if spontaneous generation occurs as a resultant of any forces, like forces would produce it again. We have never known it to occur. Should it occur the organisms thus produced would have no bonds of blood-relationship with those already in existence. With these they should show no homology, as they could have no inheritance in common. But all known organisms have common homologies. The factors of organic evolution are essentially the same for all. The unity of life amid all its diversity seems to point to origin from a common stock. If not from one stock, the lines of division between one and another are hidden from us. The study of embryology breaks down the time-honored branch lines of vertebrates, articulates, mollusks, and radiates. The groups of animals are more numerous, more complex, and more intertangled than Cuvier and Agassiz thought. The number of primary branches of animals or plants is uncertain, their boundaries undefined.
If spontaneous generation exists, it is a factor in evolution. If it is a factor, our explanation of the meaning and nature of homology must be fundamentally changed. But it may be that it should be changed. We cannot show that spontaneous generation does not exist. All we know is that we have no means of recognizing it. If there is now spontaneous generation of protoplasm, it cannot take the form of any creature we know. An organism fresh from the mint of creation would be too small for us to see with any microscope. It would be too simple for us to trace by any instrumentality now in our possession. It could contain but a few molecules, and a molecule in a drop of water is as small as an orange beside the sun. Our race of creatures, spontaneously generated, without concessions to environment, would grow hoary with the centuries before it came to our notice. Its descendants would have belonged for ages to the unnumbered hosts of microbes before we should be aware of its creation.
Evolution is not a creed or a body of doctrine to be believed on authority. There is no saving grace in being an evolutionist. There are many who take this name and have no interest in finding out what it means or in making any application of its principles to the affairs of life. For one who cares not to master its ideas, there is no power in the word. Evolution is not a panacea or a medicine to be applied to social or personal ills. It is simply an expression of the teaching of enlightened common sense as to the order of changes in life. If its principles are mastered a knowledge of evolution is an aid in the conduct of life, as knowledge of gravitation is essential in the building of machinery.