2 MARRIAGE AND HEREDITY 



by circumstances and then fixed by heredity. Be- 

 cause such psychological developments are unac- 

 companied by any physical changes of structure 

 in man, it would be rash to conclude against 

 the possibility of their occurring. So staunch a 

 Darwinian as Wallace has assumed that the mental 

 adaptability of man will henceforward enable him 

 to meet all changes in his surroundings without 

 the aid of physical selection ; ^ and the theory 

 of a psychological process of evolution superposed 

 upon the physical has certainly much to recommend 

 it. 



Such sentiments as the detestation of marriages 

 between brother and sister, esteem for chastity, and 

 the modern respect and deference shown to woman 

 as the "weaker vessel," are all sufficiently deep- 

 rooted in the Englishman's nature to be called in- 



^ " From the time when the social and sympathetic feelings came 

 into active operation, man would cease to be influenced by selection 

 in his physical form and structure. As an animal he would remain 

 almost stationary, the changes in the surrounding universe ceasing 

 to produce in him that powerful individual effect which they exer- 

 cise over other parts of the organic world. But from the moment 

 that the form of his body became stationary, his mind would be- 

 come subject to those very influences from which his body had 

 escaped. Every slight variation in his mental and moral nature 

 which would enable him the better to stand against adverse cir- 

 cumstances would be preserved and accumulated." — Paper, "The 

 Action of Natural Selection on Man," by A. R. Wallace, 



