6 EVOLUTION AND ANIMAL LIFE 



happens in time or is encountered in space promotes evolution. 

 But the kind of evolution thus produced is very different in 

 different kinds of objects. 



Biological evolution and cosmic evolution are not the same. 

 From the biological side a certain objection must be made to 

 this philosophical theory of universal or cosmic evolution. In 

 organic and inorganic evolution there is much in common so 

 far as conditions and results are concerned; but these likenesses 

 belong to the realm of analogy, not of homology. They are not 

 true identities because not arising from like causes. The evo- 

 lution of the face of the earth forces parallel changes in organic 

 life, but the causes of change in the two cases are in no respect 

 the same. The forces or processes by which mountains are 

 built or continents established have no homology with the 

 forces or processes which transformed the progeny of reptiles 

 into mammals or birds. Tendencies in organic development 

 are not mystic purposes, but actual functions of actual organs. 

 Tendencies in inorganic nature are due to the interrelations of 

 mass and force, whatever may be the final meanings attached to 

 these terms or to the terms matter and energy. It is not clear 

 that science has been really advanced through the conception of 

 the essential unity of organic evolution and cosmic evolution. 

 The relatively little the two groups of processes have in common 

 has been overemphasized as compared with their fundamental 

 differences. The laws which govern living matter are in a large 

 extent peculiar to the process of living. Processes which are 

 functions of organs cannot exist where there are no organs. 

 The traits of protoplasm are shown only in the presence of 

 protoplasm. For this reason we may well separate the eA^olu- 

 tion of astronomy, the evolution of dynamic geology and of 

 physical geography, as well as the purely hypothetical evolu- 

 tion of chemistry, from the observed phenomena of the evolution 

 of life. To regard cosmic evolution and organic evolution as 

 identical or as phases of one process is to obscure facts by 

 verbiage. There are essential elements in each not shared by 

 the other or which are at least not identical when measured 

 in terms of human experience. It is not clear that any force 

 whatever or any sequence of events in the evolution of life is 

 homologous with any force or sequence in the evolution of 

 stars and planets. The unity of forces may be a philosophical 

 necessity. A philosophical necessity or corner in logic is un- 



