Control of Heredity: Eugenics 313 



ilies continues to decrease at the present rate for the next 300 

 years, all the survivors at that time could be sent back in the 

 original "Mayflower." But there is no reason to suspect that 

 the decreasing birth rate will go on indefinitely at a constant ratio, 

 and to assume that it will do so is merely to look forward to the 

 extinction of all families, classes, races and nations in which the 

 birth rate has been decreasing ; this includes practically the entire 

 population of the United States and Western Europe and it is 

 evident that such a result while theoretically possible is not at all 

 probable. Considering the large number of collateral lines which 

 have come from the "Mayflower" stock and the enormous num- 

 ber of individuals who think they can trace their ancestry back 

 to the "Mayflower," it is incredible that all these should be re- 

 duced to a company no larger than that which came over on that 

 famous ship. 



Broman points out that most noble families of Europe die out 

 (probably the direct male line only is meant) after 100 to 250 

 years and generally do not live beyond the third generation. The 

 same is true of the families of great scholars, artists and states- 

 men. Possibly one cause of such declining fertility may be found 

 in too great brain activity, but there is no doubt that in many in- 

 stances it is due to luxurious living. On the other hand bodily 

 fatigue and simple living favor fertility in both ariimals and men. 

 Wild animals brought into captivity where they have comfortable 

 quarters and an unwonted abundance of rich food are usually 

 infertile ; and the conditions of life of the upper classes of society 

 are almost as unfavorable to fertility as is captivity with wild ani- 

 mals. It is evident that if we had fewer luxuries we could have, 

 and could afford to have, more children. 



But animals in captivity may gradually become adapted to their 

 new conditions so as to become fertile, and there is evidence that 

 man also may undergo a slow adaptation in this regard to condi- 

 tions of high civilization. Some royal families of Europe go back 

 six or eight hundred years, and in general if a family survives 



