42 2 READINGS IN BIOLOGICAL SCIENCE 



in Drosophila, it may take several hundred men a hundred years or more 

 to do working on man. Given sufficient time, and the development of new 

 tools of research which will surely take place, a fairly complete genetics 

 of man is possible. Whether its practical applications will be important, I 

 leave to you to decide. Does your experience in plant and animal genetics 

 lead you to think that the average man's socially valuable qualities in our 

 changing environment could be improved by creating conditions in which 

 superior strains have the larger families and in which the breeding of in- 

 ferior strains is effectively discouraged? 



VIII 



We have been considering only the sciences relating to individual dif- 

 ferences and individual development, and the contributions which these 

 sciences may make to the improvement of human beings. But the study of 

 man can not proceed independently of his environment and his activities, 

 which are the field of the so-called social sciences. Nor can the social 

 sciences proceed successfully without more knowledge of this strange 

 and complicated creature, man. The development of the science of man 

 should therefore, have another important effect in the contribution it will 

 make to the sciences which deal with the behavior of men in the mass and 

 their relations to each other. 



All branches of sociology are at present handicapped by lack of knowl- 

 edge of the human material whose activities they are studying. The postu- 

 late of the economic man, impervious to all other emotions, does not add 

 to the reality of economics. Perhaps the new field of population study 

 provides the best example of the interdependence of studies of man and 

 studies of man's activities. Here the analysis and forecasting of total popu- 

 lation trends has been revolutionized since 1925 by the introduction of 

 procedures for taking changes in age and sex composition accurately into 

 account. It is safe to say that the error in population forecasts for the United 

 States for the next thirty years has been cut in half by the application of 

 these techniques, and equally important information about future age dis- 

 tribution has been added, which was wholly lacking before. 



The study of the adjustment of the population to resources in difl^erent 

 parts of the nation, which had never been given serious attention before 

 1930, has been developed to the point where its results already have very 

 practical and far-reaching significance. The study of differential reproduc- 

 tion rates, which prior to 1930 had been based chiefly on such fragmen- 

 tary and inaccurate data as reports by college students about the numbers 

 of children in their fathers' families, has been extended and refined until 

 it is possible to describe the reproductive tendencies of most population 

 groups in the United States with considerable accuracy, and we are now 

 beginning to get accurate information on how these rates are changing in 

 different groups under different conditions. 



