Evolution made plain

Addison said, “The real substance of a bulky volume can be condensed into a small pamphlet.”; and it is believed that the fundamental principles of a great scientific discovery like evolution can be outlined in a few pages, and in a way so plain and in words so simple that any one who is at all interested can get a fairly good understanding of its scope. With this idea in mind an attempt is here made to explain evolution, to tell what some of its laws are and how they work, and to present briefly some of the evidences that support the doctrine.

Contrary to popular belief evolution is not confined to the origin of man, but it explains how all living things have become as we now see them, and how and why the most of them are being changed. It teaches that all living species of plants and animals, including man, also the thousands of extinct species which have left their fossil records in stratified rocks, have been developed from a few small and simple forms—probably one, and that a mere cell. And it shows, too, that this has been done by the operation of natural laws, the same laws we see in operation today.

Evolution does not teach that every living thing is “day by day, in every way, growing better and better.” On the contrary, it shows that many species deteriorate, are driven to the wall and become extinct, while only the best fitted survive. For instance, of the twenty-five orders of reptiles in the Jurassic period—known to the geologists by their fossils—only five have come down to our times. But out of the reptilian orders, then the highest forms of living things, have come the superior orders of later times—birds and mammals. And this is evolution.

We sometimes hear the statement that scientists are not in agreement in regard to evolution. The point of disagreement is in respect to the part played by natural selection in the development of species, and not as to whether or not evolution is a fact. The discussion is in regard to the _how_ of the fact and not the fact itself. No great scientist since Agassiz, who died in 1873, has opposed evolution.

Neither does evolution teach that one species may develop into another, as that the goat may develop into the deer, or that the ape may evolve into man. For one species to become another existing species it would have to take the back track to the point where the two species began to diverge and travel the other route—which of course would be impossible. This may help in getting the idea: the larger divisions and groups of animals (fishes, reptiles, mammals, etc.) may be compared to the main or primary branches of a tree, the families and orders (as the deer, the cat, and the dog) to the secondary branches growing from the primary ones, and the species to the further divisions of the secondary branches. Now we can see that one species can no more become another—that is, any now existing—than one branch of a tree can become another. A species can, in time, if subject to the proper conditions, split into varieties which, if developed far enough, may become distinct species. But no one of these species can be said to have been evolved from a contemporary species, for all have been changed, and the stock from which they came has ceased to exist as such. Each of the existing species would have a distinct name such as, for instance, cow, bison, Cape buffalo, yak. Now suppose the fossil remains of the common ancestor of the above-named species were found—what should it be called, cow, bison, Cape buffalo, or yak? It would be neither, for it would probably differ as much or more from them as they differ among themselves. Thus is laid to rest the idea that evolution is a theory that man was evolved from, or by way of, the monkey or the ape. They are as distinct species as is man himself.