EVOLUTION, History of. In travers ing the history of natural science as in travers ing the history of any phase of human thought and activity, we seek constantly for new things, for the precise time of the discovery of the new fact, the announcement of the new idea, the formulation of the new understanding or philosophy. But nothing comes wholly new into the world; the world and its content are all the result of development and growth. So correspondingly very little comes wholly new into history; and the history of evolution is no exception to the rule. The history of evolution clearly• reveals that the evolution idea is the result of a long evolution itself ; it is impossible to say just when the ,idea came first into its more primitive form of being, or just when its principal modifications or accretions occurred, or when its present form was finally determined. In tracing the history of the unfolding of the evolution idea we shall find that the conspicuous achievements in connection with it have not been the discovery of absolute newness, but the recognition and detennination and general establishment of the important ideas and con ception germs among the host offered.
An eminent American naturalist has defined three stages in connection with the discovery of the laws of science: First, a stage of dim suggestion and pure speculation with little ref erence to facts; second, a stage of the statement of a working hypothesis to explain certain facts; and, third, the proof or demonstration of the law by facts. These stages can be recog nized in the history of evolution. The first corresponds with the period of the Greek phi losophers; the second with the post-Greek, pre Darwinian period, and the third with the Darwinian and post-Darwinian period.
The evolution theory was largely anticipated, at least by suggestion, by the Greeks. They have left writings that can easily be interpreted as more or less clearly outlining the essential conception of organic evolution. Empedocles (493-435 a.c.), for example, who has been called father of the evolution idea," be lieved in spontaneous generation as the explana tion of the origin of life, and he believed that different forms of life were not produced simultaneously. Plant life came first and animal life only after a long series of trials, but the origin of the organisms was a very gradual process. °All organisms arose through the fortuitous play of the two great forces of nature upon the four elements. Thus, animals first appeared not as complete individuals, but as heads without necks, arms without shoulders, eyes without their sockets. As a result of the triumph of love over hate, these parts be gan to seek each other and unite, but purely fortuitously. Thus out of this confused play of bodies all kinds of accidental and extraor dinary beings arose." But the unnatural products soon became extinct because they were not capable of propagation. After the ex tinction of these monsters other forms arose which were able to support themselves and multiply. Thus, if one cares to, one may see in the ideas of Empedcsles the germ of the theory of the survival of the fittest, or natural selection.
Aristotle (384-322 B.c.), the greatest of the
Greek natural philosophers, believed in a com plete gradation in nature, a progressive de velopment corresponding with the progressive life of the soul. Nature, he says, proceeds con stantly by the aid of gradual transitions from the most imperfect to the most perfect, while the numerous analogies which we find in various parts of the animal scale show that all is gov erned by the same laws; in other words, nature is a unit as to its causation. Man is the highest point of one long and continuous ascent. Aris totle perceived a marvelous adaptation in the arrangement of the world, and felt compelled to assume intelligent design as the pnmary cause of things. Nothing, he held, which occurs regularly can be the result of accident: Aris totle rejected the crude conception of Empe docles of the survival of adapted, and the ex tinction of unadapted, beings. aIt is impossible that these adapted parts should arise in this manner [of Empedocles]; for these parts and everything which is produced in nature are either always, or for the most part, adaptively produced; and this is not the case with any thing which is produced by fortune or chance even as it does not appear to be fortune or chance that it frequently rains in winter . . . As these things appear to be either by chance or to be for some purpose, and we have shown that they cannot be by chance, then it follows that they must be for some purpose. There is, therefore, a purpose in things which are pro duced by and exist from nature." The Greeks, taken altogether, suggested more or less crudely the idea of the gradual development of organisms, the idea of the elimination of mistakes in production, and therefore the idea of the survival of the fittest, the idea of the adaptation of parts or the fit ness of certain structures to certain ends, the idea of intelligent design constantly operating in nature, as also the idea of nature being con trolled by the operation of natural causes due in the beginning to the laws of chance. After all, however, in how far are we justified in reading into a happy suggestive phrase or sentence of any Greek speculative thinker a real conception of that idea of the origin and de velopment of organic nature that we hold to-day under the name of Evolution? Following the Greeks the evolution idea was left in the hands of the theologians, natural philosophers and naturalists of the long period from Augustine (1st century A.D.) to the end of the 17th century, a period chiefly ruled by the Mosaic interpretation of the origin of organic life and its variety. Augustine, him self, large-minded man that he was, gave a liberal and naturalistic interpretation of the Mosaic record, favoring potential rather than special creation and teaching that in nature we should not look for miracles, but laws. But opposed to him were almost all the other churchmen, and their rigid adherence to the Mosaic interpretation controlled almost all thinking about life for many centuries. The great Evolution idea lay practically dead from the time of its foreshadowings by the Greeks until the time of the speculative natural philoso phers of. the 16th and 17th centuries.