THE DECLINING BIRTH RATE 139 



among the thousand [the number investigated] being married. 

 None the less it is obvious that the families are not self-perpet- 

 uating. The scientific men under 50, of whom there are 261 with 

 completed families, have on the average 1.88 children, about 12 

 per cent of whom die before the age of marriage. What propor- 

 tion will marry we do not know; but only about 75 per cent of 

 Harvard and Yale graduates marry; only 50 per cent of the 

 graduates of colleges for women marry. A scientific man has on 

 the average about seven-tenths of an adult son. If three-fourths 

 of his sons and grandsons marry and their families continue to be 

 of the same size, a thousand scientific men will leave about 350 

 grandsons to marry and transmit their names and their heredi- 

 tary traits. The extermination will be still more rapid in female 

 lines." 



From the foregoing data we may draw several conclusions 

 regarding the effects of our present differential birth rate. 



1 . We are probably losing the elements of our population that 

 belong to native American stock. Wherever data have been 

 collected sufficient to base a judgment upon regarding the birth 

 rate of native Americans, it has been shown that, with our existing 

 marriage rate and death rate the birth rate is insufficient to repro- 

 duce the population. The increase of our population comes 

 mainly from immigrants and the children of immigrants. The 

 eugenic effect of this is good or bad according to the qualities of 

 the immigrants of foreign born stocks, and this problem cannot 

 be solved in any general or off-hand way. 



2. We are losing the elements of our population that have 

 achieved success financially, socially, or in the field of intellectual 

 achievement. Speaking generally, none of these classes is repro- 

 ducing itself. This condition is quite as bad in Europe, at least in 

 several countries, as in the United States. It constitutes a very 

 serious menace to our present social welfare, and one which is 

 striking at the very roots of our civilization. The menace is all 

 the more dangerous because its effects do not, like those of war, 

 pestilence or famine, obtrude themselves upon our notice. The 

 forces for evil that work insidiously are the most to be feared be- 



