GENETIC EFFECTS 13 



another for many generations and for many hundreds of millions of individuals. Human 

 geneticists have only begun to exploit this special advantage. 



We are poorly informed of the way in which natural selection is now operating on human 

 populations. Only after a very detailed study of mortality and fertility rates and the factors 

 influencing them will we be in a position to give reasonably clear answers here — and only 

 then will we be able to make reasonably sound estimates as to the future fate of mutant genes 

 and their effects on the population bearing them. 



Human population studies should include vital statistics on genetic abnormalities and 

 diseases as well as the results of metrical, physical, physiological, mental, and behavioral 

 tests. Particularly important may be detailed vital statistics, as related to the level of con- 

 sanguinity, in populations now or recently living under primitive conditions more nearly 

 similar to those under which present gene frequencies may have been determined. 



One may question whether it is possible to establish artificial populations of experi- 

 mental animals that will approximate the reproductive potential and the breeding structure 

 of human populations. Nevertheless it is important to learn as much as possible about the 

 behavior of such populations under varying conditions, including exposure to different levels 

 of radiation. 



There are some considerations in human populations studies that are not important in 

 connection with populations of other organisms. It is not easy to see how they can be studied 

 directly, but they seem worth pointing out. One such consideration is that human society 

 depends on diversity of performance among its members, and on very high mental qualities 

 among at least some of them. In the absence of any precise information on the extent to 

 which mental qualities are inherited, it is not now possible to evaluate the genetic component 

 in this requirement. But the fact remains that it is possible that a human civilization might 

 conceivably collapse simply from becoming qualitatively inadequate, even if reproductive 

 selection of certain kinds were operating with high intensity and the number of individuals 

 in it remained at a level that was previously optimal. 



Another consideration is that natural selection is an impersonal process that often 

 involves suffering. On ethical grounds, many geneticists would like to see methods that involve 

 less human suffering come into more general use for the control of the genetic constitution of 

 human populations. This seems at present a Utopian idea, but it remains one that many 

 biologists hold to be desirable. If significant advances in this direction should be made in the 

 future, they will necessarily have a bearing on the genetic hazards of increased exposure of 

 man to high-energy radiation. 



4. Basic Research 



The Committee feels that it cannot too strongly urge that the pace of basic research in 

 genetics be increased, for answers to many of the practical questions posed above will surely 

 come in this way. 



Encouraging progress has been made in recent years in understanding the physical and 

 chemical nature of genetic material and every effort should be made to extend this under- 

 standing as rapidly and as far as possible. We need to know more about the nature and or- 

 ganization of genetic specifications, how they are replicated, the manner in which they are 

 changed through both spontaneous and induced mutation, and the way they are used in 

 development and in physiological activities. 



