494 EVOLUTION, GENETICS, AND EUGENICS 



London, has shown in the most exact and elaborate study ever made 

 of the influence of heredity upon the criminal tendencies of men — or 

 what more technically is called the "etiology of crime" — that heredity 

 is by all means the more important factor in the problem. Some 

 families easily react, naturally, to high social ideals, and some lack 

 the foresight and the power to develop that true synthetic wisdom of 

 life which we call in a general way self-control. Education and en- 

 vironment will alter the weight and influence of these factors within 

 each individual, but I am not aware of sufficient evidence to prove 

 that they will much alter the central tendencies either of such indi- 

 viduals or of such families. 



Perhaps Woods's illustration will illuminate this problem. As he 

 pointed out in 191 2 at the First Eugenics Congress in London (the first 

 time, I think, this distinction had been made), it is only when we 

 come to measure the differences between one or two groups of indi- 

 viduals, that we can really separate heredity from environment. 

 When we consider, as Woods suggests, what causes a white man to be 

 white or a negro to be black, or one person to have brown eyes and one 

 blue, it is evident that these characteristics are the resultant of all the 

 combined forces of heredity and environment. We can not, therefore, 

 by any means now known, separate the two sets of forces within any 

 one individual. But that the differences in pigmentation between the 

 white and black races are almost wholly due to the differences in their 

 germ plasm, no one can very well doubt. True, a tropical sun will 

 develop all the skin pigment a white man has the power to produce, 

 and rearing a negro in a northern climate will reduce his pigmentation ; 

 but when placed in the same climate their differences are almost wholly 

 due to heredity. 



Therefore we can not consider the heredity-environment problem 

 with much assurance of success, either in method or logic, unless we 

 consider it as the problem of the differences among men. And since, 

 as Thorndike pointed out long ago in his Educational Psychology, the 

 prizes of life, whether of health or wealth or social position, are nearly 

 all relative matters, the result is that heredity is the most important 

 factor in determining who shall secure these prizes and who shall not. 

 If the ideal of human health were an individual who could barely 

 hobble about, then to attain this minimum of energy would be our 

 highest ambition. The healthiest man would be one who was almost 

 helpless. Health would still be, as it is now, a relative matter. Just 

 so wealth and influence are relative matters. Among our ancestors a 



