Evolution Theory and Darwin’s Early Influence on Science
Whether the differentiations between the high groupings termed Classes and Sub-kingdoms might be accounted for in the same way is a much more difficult question. The differences that distinguish the mammals, birds, reptiles, and fishes from each other, though immense, nonetheless appear to be of a similar nature as those that describe a mouse from an elephant or a swallow from a pheasant. But the vertebrate animals and the insects are so largely diverse in their form and structure and in the very design of their body structure, that protesters may not unreasonably question whether it true that the creatures can all have been derived from a single common ascendant by way of the very same natural laws that explicate the distinction of the various species of birds or of reptiles.
In the pre-Darwin era, the broad majority of natural scientists held firmly to the belief that species were ontologically produced, and had not been derived from other species by any action perceivable to us. There was, then, no inquiry relating to the origination of families, orders, and classes, because the “origin of species” was thought to be an unsolvable problem. Today all transformed. The general scientific and literary world assumes, as a matter of general knowledge, the origin of species from other related species by the ordinary process of natural birth.
What we may expect a trusted theory will allow us to grasp and follow out in some detail those changes in the form, structure, and relations of animals and plants that are transformed in short periods of time, geologically speaking, and which we can observe now at present time. We may expect our theory to explain adequately most of the lesser and superficial differences which separate one species from another. And, in conclusion, we may expect that it describe many troubles and to harmonize many incongruities in the overly complex affinities and relations of living things. Darwin’s theory acheives these demands. It establishes how, by way of some of the most universal and ever-acting laws in nature, new species are needfully produced, while the old species become extinct. Evolution theory also enables us to understand how the constant processes of these laws during the long periods is calculated to bring about those greater divergences represented by the distinct genera, families, and orders into which all living things are classified by naturalists.
Fortunately the weightiness of this matter has been lightened with a good dose of evolution humor, popping up on web sites and office doors. See some of this evolution humor here.

