PROGRESS SHOWN IN EVOLUTION 

 By Julian Sorrell Huxley 



Honorary Lecturer in Zoology, K'trgs College, London University 



Some seem to suppose that evolution is synonymous with 

 change, even if the change is disorderly and chaotic; but if 

 vv^e 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 devel- 

 opment of each human being and each familiar animal from 

 the tgg to the adult stage, we find that one of the character- 

 istics 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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