S6 Social Environment 



more precisely than it could be done before, the 

 strength of ancestral influences. It was found, 

 for example, that such physical characters as 

 height and weight, though transmitting with 

 great variability, showed a dependable regu- 

 larity when a large number of cases were con- 

 cerned. Just as the insurance actuary found 

 that the duration of life, so uncertain for the 

 individual, became a predictable matter when 

 dealt with in the mass, so the biometrician dis- 

 covered laws of heredity through the handling 

 of extensive data. 



As a result of the successful study of the 

 transmission of physical characters, attention 

 naturally turned to the investigation of mental 

 and moral traits in human heredity. Profes- 

 sor Pearson and his coworkers^ easily showed 

 that intellectual ability exhibits a measurable 

 intensity of inheritance, much as physical char- 

 acters do. Their proof, to be sure, sometimes 

 fails to convince, owing to the difficulty of 

 discriminating between biological and social 

 heredity, yet on the whole they have estab- 

 lished their case. Dr. F. A. Woods, in his 



1 Eugenics Laboratory Memoirs, particularly No. i, by 

 Schuster, London. Also An Introduction to Eugenics, 

 p. 10. 



