158 ESSAYS OF A BIOLOGIST 



that which is found in other mammals. In most 

 higher animals progress is brought about chiefly by 

 natural selection operating upon individuals, al- 

 though in a few forms selection operates chiefly upon 

 groups of communities: in both cases the changes in 

 the inherited constitution of the species are the im- 

 portant changes. In man, however, in all except 

 the very early stages of his development, changes in 

 inherited constitution have been small and unim- 

 portant, and the chief changes of evolutionary signif- 

 icance have been those in tradition; selection among 

 individuals has been of relatively little importance, 

 and selection has fallen mainly upon groups and, 

 to an ever-increasing extent, upon their ideas and 

 traditions. 



In spite of differences in method as between dif- 

 ferent 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 

 obvious rule — is that acquisitions are not thrown 

 away when change occurs, but built upon, utilized 

 for some new function. The endostyle of the lowest 

 chordates, part of a very primitive type of feeding 



