Part 1

POCKET SERIES NO. 467 Edited by E. Haldeman-Julius

Evolution Made Plain

John Mason

HALDEMAN-JULIUS COMPANY GIRARD, KANSAS

Copyright, 1923, Haldeman-Julius Company.

EVOLUTION MADE PLAIN

The time has come when scientific truth must cease to be the property of the few--when it must be woven into the common life of the world.--Agassiz.

Read not to contradict and confute, nor to believe and take for granted, * * * but to weigh and consider.--Bacon.

The man who will not investigate both sides of a question is dishonest.--Abraham Lincoln.

Intolerance is the product of an ignorant, primitive mind. We should tolerate anything of an intellectual nature except intolerance. Freedom of opinion is the root, flower and fruit of liberty--its very essence.--Anonymous.

WHAT EVOLUTION IS AND IS NOT

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.

GEOLOGICAL EVIDENCES OF PROGRESSIVE DEVELOPMENT

All life on this globe is divided into two great classes, vegetable and animal. All animals belong to one or the other of two grand divisions: invertebrates (those without backbones) and vertebrates (the backboned). The latter class, comprising more than 30,000 known species, is subdivided into five great groups: fishes, frogs, reptiles, birds and mammals. At the top of the highest group, mammals (those which bring forth their young alive), is man. Birds and mammals were evolved from the reptiles--both offshoots of the same stock--and are contemporaneous in development and descent.

The various classes and groups of animals, both in the order of development from the simple to the complex and in the time of their arrival, are in the order named: first the small, one-celled animals (many species of which are found today) then more complex organisms of the invertebrate division, later the fishes, amphibians, reptiles, and mammals, including man.

The story told by the geologist is in perfect agreement with those laws of development which we call evolution. The lowest, simplest forms of life are the oldest as is shown by their fossil remains (bones, shells, etc.) found in stratified or water-laid rock. These fossils were deposited in sediment as it formed in sea and lake thousands and millions of years ago. In the movements of the earth’s crust the sediment of ancient sea and lake bottoms was raised above the water and became land, the sediment hardening into rock. All sediment is formed on a level, but in its up-heaval--generally slow, sometimes violent--it is often tilted at various angles exposing its edges. It is from this out-cropping, stratified rock (the sum of which is often several miles in depth) that forms the outer part of the earth’s crust that the geologist reads the story of creation.

The oldest or lowest water-laid rock is the archaean in which there are no fossils. Above this, in the stratum formed in a later period are found evidences of the beginnings of life. After millions of years of growth and development the shell fish, at the top of the invertebrate group, is produced. Then comes a period of uncounted millions of years in which the fishes, the lowest of the vertebrates, are being developed--millions of years to bridge the chasm between the two main divisions of the animal kingdom; millions of years to produce a backbone! Other long periods of time, filled with change and development, come and go--the age of the coal plant and of the frogs, succeeded by the age of reptiles, giant monsters, cold-blooded and of small brain, swarming sea and land. Long ages pass; the reptilian monsters have become extinct, leaving as their representatives only a few dwarfed species--the crocodile, the lizard, the snake, the turtle. Of mammals the lowest orders arrive first, followed by the more highly developed until finally man appears.

Naturally, fossils of land animals are few compared with those of marine animals. Practically all the remains of the latter sank and were covered with the slowly accumulating sediment, while the bones of the former only rarely were swept out to sea and lake. Rarest of all fossils are those of man. A few have been found antedating history by several thousand years, but we get a far more complete knowledge of our primitive ancestors from the tools and weapons that they left in sediment and drift before the dawn of the present era. We can trace his progress upward through all degrees of culture from the rude old stone age of a hundred thousand years ago, through the new stone age, the copper and bronze age, and the iron age to the beginning of written records.

Yet, so old is our planet and so long ago since life dawned on it--so long even since the first mammals appeared--that man’s arrival a hundred-or-so thousand years ago is but as yesterday. To paraphrase an illustration by Slade and Ferguson: “Suppose we take the earth as 365 million years old, and consider this period as a year, one million years being taken as a day.” Then, on this scale the vertebrates came into existence late in the summer or early fall, the mammals not earlier than the end of November, and “the whole period of man is not likely to have been further back than the evening of December 31st, and the earliest historic evidence (in Egypt) is not more than ten minutes before the last midnight.”--“the last midnight,” of course, being the present.

EVIDENCES OF EVOLUTION

Of the many evidences of the kinship of all animals including man only a few can be mentioned in this book. All animals, man included, are constructed on the same general plan. They have the same organs--brain, heart, lungs, digestive tract, nerves, skin--performing the same functions for the same purposes. The skeleton of man can be compared, bone for bone, with that of a monkey, bat or seal. The bat’s membranous wing is ribbed with bones corresponding to the bones of a monkey’s or a man’s hand. The wing of both the bat and the bird has one bone from the shoulder to the first joint, and two bones from the first to the second joint, like the fore leg of quadrupeds and the arm of man--thus proving that the fore leg, the arm and the wing are only modifications of the same limb. The biped bird and biped man are modified quadrupeds.

All the five hundred muscles of the human body correspond with the muscles of other mammals. Even the brain, wherein man differs most from the lower animals, has the same chief fissures and folds in both man and the animal nearest man, the orang-outang. Man and the other animals have the same five senses and the same sense organs. They in common have the same basic emotions, such as surprise, jealousy, pride, hatred, shame, anger, grief, affection, and a sense of the ludicrous. Bucks says, “So is man’s so-called human mind rooted in the senses and the instincts of all his ancestral species; and not only so, but these senses and instincts still live in him, making up, indeed, far the larger part of his current everyday life; while his higher psychical life is merely the outgrowth and flower of them.”

The old formula was: “Man is governed by reason; brutes by instinct.” But science has proved that lower animals are not guided altogether by instinct, that many of their actions are the results of mental activities remarkably similar to reasoning. On the other hand man himself has instinct--and well for him that he has, for his reason, as yet, is only partially developed. If we will but subtract from the sum of man’s actions, not only those prompted by instinct, but those also that result from habit, custom, prejudice, and the emotions of anger, revenge, vanity, and other elemental passions, we will not feel like crying from the housetops that “man is governed by reason.”

Man and the lower animals have similar diseases. He is liable to contract from, or communicate to them, such diseases as glanders, hydrophobia, cholera, tuberculosis. Drugs, tobacco and alcohol have the same effects on animals as on us.