THE GOAL OF EVOLUTION 245 



become too variable with a dangerous content of lethal 

 genes. H. S. MuUer and others are alarmed by the rather 

 careless use of radiation in general and by the now truly 

 dangerous radioactive "fall out." The natural variability of 

 man's germ plasma, it would seem to me, is not a menace, 

 but on the contrary a possible way, however remote, in 

 which he may eventually evolve the kind of individuals who 

 will more readily react to social life and who will have the 

 innate courage to seek consciously and unconsciously for 

 answers in nature and not in superstition. There is no doubt, 

 however, that the radioactive "fall out" of a major atomic 

 war could produce a generation of monsters and make man's 

 future precarious for generations to come. The end-result 

 would depend on how widespread the "fall out" was and for 

 how long a time, as it would take a very thorough dosing to 

 destroy all men everywhere. The expectation would be that 

 somewhere and somehow untouched men would survive, 

 and natural selection would eventually eliminate the mon- 

 sters. 



There are other dangers. The mental level of the man of 

 the future, if left to the mercy of the forces now in action 

 in our populations, may be very undesirable. There are 

 many who do not believe that there is any birth differential 

 working against the upper intelligence groups, as was 

 brought out in Chapter 15. The evidence that there is a de- 

 cline of 2 to 4 per cent per generation in average intelligence 

 in the United States and Great Britain is good, but possibly 

 not conclusive. In the rest of the world a similar decline 

 could be expected under the same industrial conditions. The 

 former force of natural selection which brought man 

 through his primitive beginnings up to the Industrial Revo- 

 lution on the basis of the survival of the more intelligent 

 may still be working in many parts of the world; but as most 

 of the world is finally industrialized it will cease to work in 

 any real sense. This could be the greatest menace that faces 

 civilization in the next few hundred years. Even if this birth 



