The Doctrine of Evolution | Page 5

be just what we find
now. This is the teaching of the doctrine of evolution. It is a simple
brief statement of natural order. And because it has followed the
method of common sense, science asserts that changes have taken place,
that they are now taking place, and furthermore that it is unnecessary to
appeal to other than everyday processes for an explanation of the
present order of things.
Wherever we look we see evidence of nature's change; every rain that
falls washes the earth from the hills and mountains into the valleys and
into the streams to be transported somewhere else; every wind that
blows produces its small or greater effect upon the face of the earth; the
beating of the ocean's waves upon the shore, the sweep of the great
tides,--these, too, have their transforming power. The geologists tell us
that such natural forces have remodeled and recast the various areas of
the earth and that they account for the present structure of its surface.
These men of science and the astronomers and the physicists tell us that
in some early age the world was not a solid globe, with continents and
oceans on its surface, as now; that it was so very hot as to be semi-fluid
or semi-solid in consistency. They tell us that before this time it was
still more fluid, and even a mass of fiery vapors. The earth's molten
bulk was part of a mass which was still more vast, and which included
portions which have since condensed to form the other bodies of the
solar system,--Mars and Jupiter and Venus and the rest,--while the sun
remains as the still fiery central core of the former nebulous materials,
which have undergone a natural history of change to become the solar
system. The whole sweep of events included in this long history is
called cosmic evolution; it is the greater and more inclusive process
comprising all the transformations which can be observed now and
which have occurred in the past.
At a certain time in the earth's history, after the hard outer crust had

been formed, it became possible for living materials to arise and for
simple primitive creatures to exist. Thus began the process of organic
evolution--_the natural history of living things_--with which we are
concerned in this and later addresses. Organic evolution is thus a part of
the greater cosmic process. As such it does not deal with the origin of
life, but it begins with life, and concerns itself with the evolution of
living things. And while the investigator is inevitably brought to
consider the fundamental question as to the way the first life began, as
a student of organic forms he takes life for granted and studies only the
relationships and characteristics of animals and plants, and their
origins.
But even as a preliminary definition, the statement that organic
evolution means natural change does not satisfy us. We need a fuller
statement of what it is and what it involves, and I think that it would be
best to begin, not with the human being in which we are so directly
interested, nor even with one of the lower creatures, but with something,
as an analogy, which will make it possible for us to understand
immediately what is meant by the evolution of a man, or of a horse, or
of an oak tree. The first steam locomotive that we know about, like that
of Stephenson, was a crude mechanism with a primitive boiler and
steam-chest and drive-wheels, and as a whole it had but a low degree of
efficiency measured by our modern standard; but as time went on
inventive genius changed one little part after another until greater and
greater efficiency was obtained, and at the present time we find many
varied products of locomotive evolution. The great freight locomotive
of the transcontinental lines, the swift engine of the express trains, the
little coughing switch engine of the railroad yards, and the now extinct
type that used to run so recently on the elevated railroads, are all in a
true sense the descendants of a common ancestor, namely the
locomotive of Stephenson. Each one has evolved by transformations of
its various parts, and in its evolution it has become adapted or fitted to
peculiar circumstances. We do not expect the freight locomotive with
its eight or ten powerful drive-wheels to carry the light loads of
suburban traffic, nor do we expect to see a little switch engine attempt
to draw "the Twentieth Century Limited" to Chicago. In the evolution,
then, of modern locomotives, differences have come about, even

though the common ancestor is one single type; and these differences
have an adaptive value to certain specific conditions. A second
illustration will be useful. Fulton's steamboat of just a century ago