THE TREND OF EVOLUTION 159 



lines of evolution. Physical, intellectual, and social fitness are 

 very different things, and it is possible to have any one of 

 these without the other two. The past evolution of the human 

 race has been guided by the elimination of the unfit, whether 

 physical, intellectual, or social, and the future progress of the 

 race must depend on this same process. 



The Paths of Progress. Even a cursory study of the living 

 world would justify the opinion that evolution has proceeded 

 in all possible directions; crab-like it moves forward, back- 

 ward, and sidewise. This is especially true of the minor 

 stages of evolution represented by mutations, for these ap- 

 parently occur in all directions without reference to their utility 

 or inutility; however, in order to survive and become estab- 

 lished, a mutation must run the gauntlet of natural selection 

 and injurious mutations are eliminated. Much more is this 

 true of species and larger groups which have had a longer and 

 more severe trial than mutations and are consequently 

 peculiarly adapted to their environments. In particular in- 

 stances simplification and degeneration have occurred but in 

 the main evolution has been progressive, that is, it is marked 

 by increasing complexity of structures, functions, and adapta- 

 tions, just as development from the egg to the adult is gener- 

 ally progressive, though in some instances and stages it is 

 retrogressive. Particularly when one surveys the whole course 

 of phylogeny or ontogeny it is evident that there has been 

 progress from relative simplicity to complexity. 



Definition of Progress. The very word "progress" calls 

 forth a reaction from some people not unlike their response 

 during the war to the word Kultur. A few persons seem 

 to deny the existence of any such thing as progress, while others 

 insist that it is too indefinite to admit of any formulation. 

 Undoubtedly progress may occur in many different directions 

 and toward different goals, but everywhere and always in the 

 living world, it has certain fundamental characteristics. As is 



