The Meaning of Evolution

by Samuel Christian Schmucker

There is another way of approaching this life problem, though it seems to be rather a begging of the question than a solution of it. Of recent years it has been discovered that even the very low temperatures obtained by evaporating liquid air, say three hundred degrees below zero, Fahrenheit, do not kill seeds or spores of mold. The space between the planets is undoubtedly extremely cold. We have always supposed it to be entirely too cold for life to exist in it. But we laid little stress on the fact because we had no thought of any possible life existing there. But the discovery that seeds and spores can live uninjured through extreme cold has led to an interesting suggestion. This is that when the earth became adapted to the presence of life it was infected by germs transported on meteors from some other system. According to this theory, organic dust through space is ready to infect any planet which offers the conditions under which life may arise. Of course this theory does not explain the origin of life. It pushes back that origin a little farther or supposes that life is as old as matter itself. Again we may leave to the scientist the discussion and the elaboration of this or any other theory he may promulgate concerning the origin of life. When he has established clearly the process and can produce life we will accept his explanation; meanwhile, we will always be interested in his attempts to solve the problem, but still our simple formula, "in the beginning God," serves our present needs and will satisfy us better than any as yet unverified hypothesis.

When we find through scientific investigation how life arises we will simply know how God created it in the beginning.

The next step in the understanding of early life is to study under the microscope the simplest forms which we can find in existence to-day. This, while far easier of execution than the problems which we have thus far considered, is still not without serious difficulties. But every day brings us nearer to the understanding of the structure of living things. Life the scientist cannot see. All he can study is living matter. Whether life can exist separate from living things is a problem outside the range of his, at least present, possibilities. Therefore, concerning it he has no answer whatever to give. But when we come to study living things we find that all life is associated with protoplasm. This apparently foamy, jellylike, transparent material is the only living substance in all the world. Animals and plants are larger or smaller collections of the little masses of protoplasm which we know as cells. The lowest animals are each made up of but a single cell. This consists of a small mass of protoplasm surrounded almost always by a thicker skin or covering, known as the cell wall and enclosing a complicated kernel known as the nucleus. The protoplasm seems to be the living substance itself. The cell wall is not a simple dead scum on the outside of the protoplasm, but is itself able to do certain things which can only, so far as we know, be done by living substances. For instance, of two materials dissolved in the water in which the cell floats, the wall may permit one to soak into the animal and keep the other out. The one allowed to enter will usually be found good to be used for food by the cell. The nucleus seems to store within itself the record of its past history and thus enable the cell to do in the future what its ancestors did in the past.

Such simple cells can exhibit in very low form all the activities the higher animals show in much more elaborate development. A one-celled animal can move about, can recognize the proximity of food, can engulf its food and digest it, can build up its own substance out of the digested food, can absorb oxygen, can use this oxygen in the burning of its own substance to produce its own activities, can act in response to sensation gained from outside, can throw off its waste matter produced by its own activities, and can grow. When the proper time comes its nucleus can split in two, the cell itself enclosing the nucleus can separate into two cells, each of which can grow to the size of the parent cell and repeat its life. This is as simple an animal as we have yet discovered. Every kitchen drain swarms with such creatures. On a summer day the stagnant pools are full of them. The simplest microscope will show them clearly. This is life in its lowest terms with which we are acquainted. With such life, it seems to us, the animal and plant world must have started their existence, when first the earth began to teem with living matter.

If, then, we may form any judgment concerning the first living things upon the globe by considering the simplest creatures that live here to-day, certain facts seem clear. In the first place, life began in the water, and for a long time was only to be found in the water. Single cells are so small and dry out so easily that it is necessary to their existence that they should be kept entirely moist by the presence of water all about them. It is true many of them will stand drying, but while they are thus dried they can scarcely be said to be much more than just alive. They are utterly inactive, or, as we say, they are dormant. In such conditions they become covered with a tough skin, almost a shell, and their protoplasm is itself nearly dry. Under these circumstances the life processes hardly continue at all. The protozoa, as these small animals are called, tolerate drought for a time; but they only live, in any sense worth calling living, when water is abundant and is neither very warm nor very cold. It is safe to say that the early life of the world formed in the oceans of the time. So absolutely is the habit fixed upon cells of protoplasm that even to-day the activities of the cells of higher animals depend upon the presence of moisture. The cells of our own bodies are to-day living, as it were, in an ocean. Everyone can remember far enough back to recall some time at which a tear slipped from his own eye onto his own tongue; we know our tears are salt. The tongue has tasted, undoubtedly, the perspiration from the lip on more than one summer day; this perspiration tasted as salt as the tear itself. The lymph that constitutes the "water" of a so-called "water blister" is also salty, and even the little blood one gets into his mouth in trying nature's method of stanching the flow from a cut finger gives the impression that it contains a little salt. Every fluid of the body is salty, and every cell of the body is bathed in salt water. It is too long since the ancestors of our cells swam in the seas of the Eozoic time for us to assert with any positiveness that the ancestral habit is responsible for this trait in the descendants. Sure it is that to-day our cells, like their ancestors of old, live in water, and this water is slightly salty—as were probably the Archæan seas.

The geologist tries as best he may to build up the geography of the earth in the past. He endeavors to judge from the rocks as he now finds them, where the seas, the bays, the dry land, and the mountains of earlier geological times lay. The present aspect of the earth is very recent, and earlier ages must have shown an entirely different distribution of land and water. The North American continent was certainly very much smaller than it is now. The first known lands lay close to the Atlantic seaboard and probably extended out into the water some distance beyond the present shoreline. The stretch of continent was narrow, and grew narrower as it went southward. In what is now the Canadian district, a considerable expanse probably existed in very early times. Then a great internal sea, shallower than the Atlantic, stretched its unbroken sheet over almost the entire area now occupied by the United States, while only a comparatively small hump of earth, ending in a narrower strip, lay where the great Western plateau now rears its enormous bulk.

A large portion of the history of the North American continent, with its developing animals and plants, is tied up with the gradual shrinkage of this interior sea. Slowly across the Canadian district, the Eastern and Western lands became connected with each other, while the waters progressively were pushed down the continent, which was steadily growing from the east and from the north, though less slowly from the west, into this internal sea. To-day only the Gulf of Mexico remains as evidence of the broad stretch that once extended through to the Arctic Ocean and west beyond the present position of the Rocky Mountains.

How this great Eastern backbone of the continent was produced, what sort of animals lived while these rocks were being formed, or whether this preceded entirely the existence of life upon the earth, no man to-day may surely say. In the oldest of the rocks there are beds of graphite, from which lead pencils are made. This substance is believed by the geologists to be, like coal, the remains of vegetable life. But these early rocks have been so heated and baked, so twisted and bent, that whatever forms of life they once held are now obliterated, or so altered as to give us no idea of what may have been their character.

So far as anyone can now see, this past history is wiped out forever and it will be impossible for men ever to demonstrate the character of this early life. Speculations, more or less certain, will arise. They may, after a while, seem so clear as to receive the acceptance of the scientific mind. Yet the truth remains that the early history of the earth, so far as animals and plants are concerned, is probably lost forever.

The most striking feature concerning the earliest layers of rocks in which good fossils are found abundantly is the complexity of the life. With the exception of the backboned animals, every important branch of the animal kingdom is represented, and it is just possible that we have even earlier forms of the vertebrates themselves. This, to the evolutionist, is very disconcerting. To find the great groups all well developed at least twenty-five million years ago and to find only fossils built on the same lines since almost nonplusses him. When the geologist tells him what an enormous length of time preceded the rocks in which he finds these fossils and how absolutely these earlier strata have been altered by the later geological activities he easily understands why it is impossible to find fossils in them. As a consequence, the evolutionist is forced to believe that all the earliest animals have left no clear traces behind them. Life as he first surely knows it is already extremely varied and quite well developed in some of its groups. The early animals were as well adapted to the times in which they lived as are the great majority of the animals of to-day. The reader must not infer this to mean that the animals of those days were like our present animals. They were not. No one traveling in a far country could find there animals as strange to him as would be those of the earlier stratified rocks. In these there were no fishes as we know them to-day, not a single member of the frog and salamander class, not a reptile, not a bird, not a mammal, and probably no air-living insects. It is highly doubtful whether there was any animal living upon the land and breathing the air twenty-five million years ago.