14 



The Threat 



of Overpopulation 



The tendency of all organisms to reproduce many more 

 young than are actually needed to replace the parents is a 

 basic defense against the certainty that most of the off- 

 spring will be destroyed long before they reach adult life. 

 Nature is striving in each species to compensate for such 

 losses as there may be, and since apparently she cannot es- 

 timate in advance the degree of these losses, she sets the re- 

 production drive at as high a level as possible. No organism, 

 not even man, is exempt from this basic urge of species sur- 

 vival. Nature has never found a way to avoid the turmoil, 

 the struggle, and dreadful death that results from the over- 

 pressure on the population. Ruthlessly the young are 

 crowded out, devoured by other organisms, or destroyed 

 by the accident of intolerable environmental conditions. 

 Man alone of all organisms is in a position where he finds 

 it desirable and even necessary to search out a way to con- 

 trol this tendency and to set the birth rate, as nature has 

 never been able to do, at such levels as will maintain a pop- 

 ulation at just the right numbers of individuals to utilize and 

 enjoy the world without overwhelming want and waste. 



In nature birth rates vary with the vulnerability of the 

 organism, being astronomically high in animals like the oys- 

 ter where there is a very great vulnerabihty. The female 



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