GENETICS AND EUGENICS 253 



such mutations as have been mentioned, but also by increased repro- 

 duction by the members of the dysgenic group itself. 



The Diflferential Birth Rate 



Nature keeps her creatures fit by giving reproductive advantage to 

 the best members of each species. Various dioecious animal forms 

 produce from dozens to millions of young per pair from which, on an 

 average, two individuals are selected to replace the parents. As a rule, 

 the two selected are the ones that are strongest and the most free of 

 defects — these are usually the ones that are best adapted to their en- 

 vironment. Man has, in the case of his own kind, preserved the weak 

 and defective individuals that Nature would have eliminated had it 

 not been for the application of medical science, together with public 

 health and other measures that have come with the development of a 

 humanitarian consciousness. Nothing but praise should be given to an 

 altruism that saves lives and relieves suffering, but the effect on our 

 race of man's present practice of preserving individuals that Nature 

 would have destroyed, without safeguarding the reproductive advan- 

 tage of the fitter group, is worthy of consideration. 



It has been shown by Lorimer and Osborn* that certain large groups 

 are increasing so rapidly while others are so diminishing, that the 

 surviving children of a million women of reproductive age of the first 

 category will be twice as numerous as the surviving children of a 

 similar group of women of the second classification. Carried on at the 

 same rate for three generations (which is only a long lifetime) the 

 descendants of the first groups will be sixteen times as numerous as 

 those of the second groups. 



Casual observation will make evident that such grouping is likely 

 to be on a basis of eugenicity and dysgenicity. A number of studies 

 have been made of the reproductive rate of groups classified by voca- 

 tion. These studies reveal that passing from the professional and suc- 

 cessful business classes through the various occupations to that of the 

 unskilled, transient, agricultural laborer, the number of children per 

 family rises steadily. 



Family Size in Eugenic Groups 



The vocational group made up of college teachers might be taken as 

 an example of a profession whose members have a low reproductive 



♦Lorimer, F., and Osljorn, F. ; Dynamics gf Population, Macmillan. 



