MAN 243 



little prudential restraint and consequently a high repro- 

 ductive rate. 



The problem exists in just the form we have stated it, 

 but perhaps the picture has been overdrawn. Although 

 the ratio is extremely conservative from one point of view 

 because of the low estimate of defectives and the tre- 

 mendous birth rate used, it may be considerably too high 

 by reason of our inability to allow for a proper selective 

 marriage rate between the carriers. Goddard, who has 

 made a more intensive study of these persons than any- 

 one else, is of the opinion that the heterozygotes are not 

 in the same class with pure normals. They are more or 

 less dull, stupid, lacking in real ability. For this reason 

 they are unquestionably thrown together more than would 

 otherwise be the case. They tend to form a class of the 

 population which weds within itself. This is not a whole- 

 some thing, but it is much better than having it corrupt 

 the good germ plasm of the country. Although one can 

 make no true estimate, such a selective marriage rate may 

 be high enough to revisei our ratio two or three hundred 

 per cent. Instead of 1 out of 14 being of this type, it may 

 be only 1 out of 28 or 42. At best it is food for thought. 



Enough has been said about the effect of inbreeding in 

 man to show why the numerous statistical investigations 

 on marriages of near kin have reached no concordant re- 

 sults. Hundreds of such investigations have been made. 

 The earlier ones were compiled by Huth,®'' who came very 

 near the truth considering the state of knowledge of his 

 time. The later data have been brought together by 

 ■Westermarck,^" but Westermarck was so imbued with 

 preconceived ideas of what ought to be true that he made 

 matters more chaotic than ever. The impossibility of a 



