Nature and Current Aspects of the Doctrine of Evolution.
Definitions are wearisome. But we may ask ourselves, by way of limitation, what is evolution in general and organic evolution in particular. The answer can best be given by means of illustrations. The term evolution, as today used in science, means the historical process of change. When we speak of the evolution of man-made products, like automobiles and steam engines, of social institutions like democratic government, of the crust of the earth, or solar system, of animals and plants, we mean a gradual coming into existence of what is now before us, in contrast to its sudden and miraculous creation. Such an idea is of recent origin. Our intellectual forbears of a few centuries ago thought in terms of a world created in its present form. The evolutionary point of view marked an advance from the concept of a static universe to one that is dynamic. In the phraseology of the street, the world is a going concern, historically as well as in its present aspects.
Evolution is, therefore, the doctrine of how things have changed in the past and how they are changing in the present. It may be naturally divided into its cosmic, geologic, and organic aspects, as represented by the sciences of astronomy, geology and biology.
Cosmic Evolution.
Cosmic evolution includes all other forms, for by the cosmic we mean the entire visible universe, our very bodies, as well as the farthest star. But in practice, one thinks of the cosmos as remote. And what we have in mind under cosmic evolution is the changes that are postulated by the science of astronomy. It is believed by astronomers that our solar system with its central sun, its planets and lesser bodies, has not always possessed its present form, although it has been in exitence from a remote period of time. Our earth seems to have been more molten, and before that perhaps gaseous. Although the famous nebular hypothesis of La Place has been in part replaced by other theories, the belief of modern astronomers is that our solar system and perhaps countless others have arisen by an evolutionary process whose extent is infinite in both time and space. I take it that few will combat the concepts of astronomy regarding the nature of our sun and planets. Even when some of us were children the ideas of cosmic evolution, as set forth by the nebular hypothesis, the plantesimal hypothesis, or the like is correct, but that the astronomer regards the heavenly bodies as having reached their present state by an evolutionary stage continuous through an unfathomable past and presumably to be continued into a limitless future. There is no longer talk among intelligent or educated men—or there should not be—of "heaven earth, center and circumference, created all together, in the same instant, and clouds full of water, on October 23, in the year 4004 B. G, at 9 o'clock in the morning," as was determined by the chronology of Dr. John Lightfoot in the seventeenth century. The astronomical evidence for the development of such a dynamic universe in space and time is of course limited. But it all points in the direction of evolution.
Geologic Evolution.
Geologic evolution overlaps with cosmic, since the geologist fakes the evolutionary problem where the astronomer leaves it. Geology deals with the history of our earth, how it originated and how it has assumed its present form. Astronomy deals with the origin of the earth as a planet of our solar system, Geology finds evidence that the earth was once a molten mass which has since been cooler. What may be called the "countenance" of the earth is the subject matter of geology, how the land lies at the present day, how rocks and soil are being produced, and what these facts imply regarding historical origins. The evolutionary evidence of astronomy is vague and remote, although generally accepted by the layman. The
