The Evolution Theory

The evolution or development theory declares the universe as it now

exists to be the result of a long series of changes which were so far

related to each other as to form a series of growths analogous to the

evolving of the parts of a growing organism. Herbert Spencer defines

evolution as a progress from the homogeneous to the heterogeneous, from

general to special, from the simple to the complex elements of life, and

t is believed that this process can be traced in the formation of

worlds in space, in the multiplication of types and species among

animals and plants, in the origin and changes of languages and

literature and the arts, and also in all the changes of human

institutions and society. Asserting the general fact of progress in

nature, the evolution theory shows that the method of this progress has

been (1) by the multiplication of organs and functions; (2) according to

a defined unity of plan, although with (3) intervention of transitional

forms, and (4) with modifications dependent upon surrounding conditions.

Ancient writers occasionally seemed to have a glimmering knowledge of

the fact of progress in nature, but as a theory evolution belongs to

the enlightenment of the nineteenth century. Leibnitz, in the latter

part of the seventeenth century first uttered the opinion that the earth

was once in a fluid condition and Kant about the middle of the

eighteenth century, definitely propounded the nebular hypothesis, which

was enlarged as a theory by the Herschels. The first writer to suggest

the transmutation of species among animals was Buffon, about 1750, and

other writers followed out the idea. The eccentric Lord Monboddo was the

first to suggest the possible descent of man from the ape, about 1774.

In 1813 Dr. W. C. Wells first proposed to apply the principle of natural

selection to the natural history of man, and in 1822 Professor Herbert

first asserted the probable transmutation of species of plants. In 1844

a book appeared called Vestiges of Creation, which, though evidently

not written by a scientific student, yet attracted great attention by

its bold and ingenious theories. The authorship of this book was never

revealed until after the death of Robert Chambers, a few years since, it

became known that this publisher, whom no one would ever have suspected

of holding such heterodox theories, had actually written it. But the two

great apostles of the evolution theory were Charles Darwin and Herbert

Spencer. The latter began his great work, the First Principles of

Philosophy, showing the application of evolution in the facts of life,

in 1852. In 1859 appeared Darwin's Origin of Species. The hypothesis

of the latter was that different species originated in spontaneous

variation, and the survival of the fittest through natural selection and

the struggle for existence. This theory was further elaborated and

applied by Spencer, Darwin, Huxley, and other writers in Europe and

America, and though to-day by no means all the ideas upheld by these

early advocates of the theory are still accepted, evolution as a

principle is now acknowledged by nearly all scientists. It is taken to

be an established fact in nature, a valid induction from man's knowledge

of natural order.