158 ESSAYS OF A BIOLOGIST 



when we consider the average, not at all when we 

 look at the minimum. 



The method or mechanism of progress may differ 

 in different types, and it does differ in man from 

 that which is found in other mammals In most 

 higher animals progress is brought about chiefly by 

 natural selection operating upon individuals, although 

 in a few forms selection operates chiefly upon groups 

 or communities : in both cases the changes in the 

 inherited constitution of the species are the important 

 changes. In man, however, in all except the very 

 early stages of his development, changes in inherited 

 constitution have been small and unimportant, and 

 the chief changes of evolutionary significance have 

 been those in tradition ; selection among individuals 

 has been of relatively little importance, and selection 

 has fellen mainly upon groups and, to an ever-increasing 

 extent, upon their ideas and traditions. 



In spite of differences in method as between different 

 types of organism, the tendency has been in the same 

 direction — towards a possibility of greater control, 

 greater independence, greater complexity, and greater 

 regulation or harmony. 



Looked at from the evolutionary point of view, the 

 moving, dynamic point of view, we have to think of 

 human sex-psychology in yet another way. So far 

 we have been treating it as what it is ; now we 

 must think of what it may become. 



The general rule in evolution — the natural and 



