790 



AMERICAN MEN OF SCIENCE 



might become men and women of perform- 

 ance and of genius. 



Eugenics may become the most impor- 

 tant of all applied sciencas, but at present 

 its scientific foundations must be laid by 

 the study of comparative genetics, on the 

 one side, and the study of human conduct, 

 on the other. There is more immediate 

 prospect of improving our civilization 

 than our germ plasm. It is ea.sier to 

 decrease or eliminate typhoid fever by 

 hygienic measures than to attain racial 

 immunity, although this is not equally 

 the case for tuberculosis and still less for 

 cancer. We can increase to any desired 

 extent from the existing population by 

 proper selection and training the number 

 of scientific workers in the United States. 

 The number capable of exhibiting genius 

 is limited, but many of tliem are lost 

 through lack of opportunity. It is our 

 business, it should be our principal busi- 

 ness, to improve our civilization by giving 

 opportunity to those who are fit, while at 

 the same time investigating the conditions 

 which will give us a better race. 



II. INIarriage and Number of Children 

 There are thousands of volumes con- 

 taining vital statistics, but exact studies 

 of definite groups of individuals have 

 scarcely been made. It is often assumed 

 that we must have vast numbers of cases, 

 such as are obtained by a national census, 

 in order to secure valid statistics, but in 

 some directions better scientific results can 

 be obtained by applying more careful 

 methods to a limited number of cases. 

 The difficulty in obtaining correct statis- 

 tics is not the variable error, which 

 decreases with tlie number of cases, but 

 the constant errors, which can only be 

 eliminated by proper methods. Thus, for 

 example, I find that the parents of 871 

 scientific men had families of tlie average 

 size of 4.65 children, with a probable error 

 of 0.05. The chances are even that in- 

 creasing indefinitely the number of cases 



would give a, figure varying only between 

 4.6 and 4.7, and this is as close a deter- 

 mination as is needed. But a serious mis- 

 take would be made if it were assumed 

 that the average family of the class from 

 which the scientific men come was as large 

 as 4.65. The fathers of 865 scientific men 

 died at the average age of 70.6 years and 

 their mothers at the average age of 70.2 

 years. The chances are even that this 

 figure is correct within one third of a 

 year, and this is all we need to know. It 

 would, however, be incorrect to use these 

 figures to prove that people of tliat class 

 and generation lived to the age of seventy 

 years or that the men lived longer than 

 the women. In the census of 1880 there 

 were found to be in the United States 

 170,000 more children in their second than 

 in their first year. As over one tenth of 

 all the children died in their first year, 

 this result is incredible, and the large 

 number of cases only makes the absurdity 

 more obvious. 



Table IV. Numbers and Percentages of Scien- 

 tific Men "WHO are Unjiareied in accord- 

 ance WITH THEIR Ages 



The table shows that of just one thou- 

 sand leading scientific men for whom the 

 information is at hand 105 are unmarried. 

 Eighteen per cent, of those under 40 years 

 of age are single, 10.5 per cent, of those 

 between 40 and 50, and 7.5 per cent, of 

 those over 50. According to the census of 

 1900, 17.1 per cent, of men 35 to 44 years 

 old are single, 10.4 per cent, of those from 

 45 to 54, and 7.8 per cent, of those from 

 55 to 64. There is thus a tolerably close 

 correspondence between the marriages of 

 scientific men and of the general popula- 

 tion, but the age groups of the census 



