486 READINGS IN EVOLUTION, GENETICS, AND EUGENICS 



Remembering that longevity is in general inherited, and that it is 

 found in the families of all the people of this study (since one in each 

 fraternity lived to be 90 or over) how is one to interpret this zero 

 coefficient? Evidently it means that although these people had 

 inherited a high degree of longevity, their deaths were brought about 

 by causes which prevented the heredity from getting full expression. 

 As far as hereditary potentiaHties are concerned, it can be said that all 

 their deaths were due to accident, using that word in a broad sense to 

 include all non-selective deaths by disease. If they had all been able 

 to get the full benefit of their heredity, it would appear that each of 

 these persons might have lived to 90 or more, as did the one in each 

 family who was recorded by the Genealogical Record Office. Geneti- 

 cally, these other deaths may be spoken of as premature. 



In an ordinary population, the age of death is determined to the 

 extent of probably 50 per cent by heredity. In this selected long- 

 lived population, heredity appears not to be responsible in any meas- 

 urable degree whatsoever for the differences in age at death. 



The result may be expressed in another, and perhaps more striking, 

 way. Of the 669 individuals studied, a hundred — namely, one child 

 in each family — lived beyond 90; and there were a few others who did. 

 But some 550 of the group, though they had inherited the potentiality 

 of reaching the average age of 90, actually died somewhere around 60; 

 they failed by at least one-third to live up to the promise of their 

 inheritance. If we were to generalize from this single case, we would 

 have to say that five-sixths of the population does not make the most 

 of its physical inheritance. 



This is certainly a fact that discourages fatalistic optimism. The 

 man who tells himself that, because of his magnificent inherited 

 constitution, he can safely take any risk, is pretty sure to take too 

 many risks and meet with a non-selective — i.e., genetically, a pre- 

 mature — death, when he might in the nature of things have lived 

 almost a generation longer. 



It should be remarked that most of the members of this group 

 seem to have lived in a hard environment. They appear to belong 

 predominantly to the lower strata of society; many of them are immi- 

 grants and only a very few of them, to judge by a cursory inspection 

 of the records, possessed more than moderate means. This necessi- 

 tated a frugal and industrious life which in many ways was favorable 

 to longevity but which may often have led to overexposure, overwork, 

 lack of proper medical treatment, or other causes of a non-selective 



