Page:Popular Science Monthly Volume 64.djvu/449

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T is a misfortune frequently lamented that new truth, the most precious attainment of each generation, is also the most unwelcome. We do not hasten to sweep out our stock of laboriously collected ideas, even after the worthlessness of the assortment has been declared. This conservatism of vested intellectual interests not only postpones the utilization of the results of scientific inquiry, but it has an even worse effect when it impedes further investigation and warps our perception of facts.

The great obstacle in the popularization of the fundamental and obvious biological fact of evolution was the theological dogma of the separate creation of species, and toward the overthrow of this the arguments of Darwin and his immediate followers were, of necessity, directed. After four decades the debate upon the general question may be said to have closed. The thoughtful public believes that species were not made like cakes by the baker, but that the diversity of organic nature has been attained by gradual changes and transformations, a process commonly thought of as 'evolution.' As soon, however, as we pass into the field of biology proper, and seek to know the nature and causes of this process, all unanimity of opinion vanishes. The fact of evolution is no longer doubted, but biologists are still writing thousands of pages annually in support of the most diverse and contradictory interpretations of evolutionary phenomena.

In spite of the external simplicity of the idea, evolution affords extremely complex and elusive problems, and in addition to the inherent difficulty of these, discussion is still cumbered with the original terminology. Vast quantities of argumentation wasted in attempting to convince theologians that they did not know how species were made are already forgotten, but a more troublesome legacy remains, in that the words and ideas upon which attention became focused during that struggle still darken our views of biological problems.

Evolutionists, too intent on a practical explanation of the diversity of species, seized upon the idea that organisms become adapted to environment, and disregarded the more fundamental fact that species are not by nature stationary, but have an independent motion of their own. This oversight brought us the impossible task of explaining how external conditions produce evolutionary changes, and prevented the