842 TEXTBOOK OF ZOOLOGY 



What effect college education may have on family size may be inferred 

 from other studies. Harvard graduates whose year of graduation 

 would give us reason to suppose that their families are complete, have 

 produced 1.9 children per married alumnus; allowing for the mem- 

 bers of the group who did not marry, the average falls to 1.6 chil- 

 dren. Corresponding averages for Yale are 1.9 and 1.5, for Swarth- 

 more 2.15 and 1.9, and for Vassar 2.15 and 1.25. 



A false sense of eugenic security might be prompted by the belief 

 that the figures exceeding two in the foregoing citations indicate that 

 the parents are being replaced and that any residual value represents 

 a gain. But in the cases of two-child families, what assurance have we 

 that those children will live to reproductive age, that they will marry, 

 and if they marry that they in turn will have children ? Considering 

 these possibilities, it is evident that fertile families must provide for 

 more than replacement if the group to which they belong is to be per- 

 petuated. Various computations have been made of the average num- 

 ber of children per fertile family necessary to maintain the numerical 

 strength of a group. These estimates range from 3.1 to 4. Consider- 

 ing that the current incidence of childless families in America is 

 20 per cent, probably the higher number is more nearly correct, and 

 it is not safe to place the figure at less than 3.5, or stated another 



., . , , Grandmothers t ^t ^ 



way, It IS only when ^^^^^^^ ^^ daughters -■ ^ *■>"' " «'™° «™"P 

 is maintaining itself. 



Faanily Size in Dysgenic Groups 



Various studies have shown that larger families occur among peo- 

 ple who have but a poor store of those qualities of intelligence, sta- 

 bility, and physical traits that go to make up racial excellence. Lori- 

 mer and Osborn found in their study of the school children of selected 

 eastern cities that children with the lowest intelligence scores (I.Q. 

 below 60) came from families that averaged nearly six children; that 

 those with medium scores (I.Q.'s 90 to 110) came from families aver- 

 aging less than four; and that the children of superior intelligence 

 (I.Q.'s 140 and over) came from families that averaged less than two 

 and a half children. 



The writer's study of nearly a thousand improvident families of a 

 type well known to the social workers of southwestern cities revealed 



