PROGRESS SHOWN IN EVOLUTION
By Julian Sorrell Huxley
Honorary Lecturer in Zoölogy, Kings College, London University
Some seem to suppose that evolution is synonymous with change, even if the change is disorderly and chaotic; but if we look at evolution as it actually exists, whether the long-range evolution of species from species or class from class, or the short-range evolution that occurs in the individual development of each human being and each familiar animal from the egg to the adult stage, we find that one of the characteristics of evolutionary change is its orderliness. Each step in each separate evolutionary line is orderly, its significance can be fully understood only as the result of what has gone before and as the necessary prelude to what is to come after. If we turn from single lines of evolution to the evolution of life as a whole, we can ask a new question. Granted that the separate changes of evolution are orderly, can we discern one sole or main direction, or a few main directions, in the general evolution of life? Finally, if we were to find that evolution followed only one or a few main trends, can we say that these trends or directions are, in any real sense of the word, progressive?
The answer to the first of these two questions is definite enough. In its march through time life does follow certain main directions. This fact can be shown by actually tracing the history of animals through geological time by means of their fossil remains, by deciphering the history of the race
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