i88 THE TREND OF THE RACE 



we must bear in mind that their better environment is to a large 

 extent the result of their belonging to hereditary stocks at least 

 a little above the general average of humanity. If the birth rates 

 of the classes that achieve success by virtue of their inherent 

 superiority were as high or nearly as high as it is among their 

 less favored brethren the general level of ability would doubtless 

 be raised through natural selection. Unfortunately under our 

 present social conditions natural selection and reproductive 

 selection frequently work in opposite directions, and the evidence 

 points to the conclusion that the influence of the latter is gener- 

 ally the more potent. 



For a number of years Professor Karl Pearson and several of 

 his associates have been endeavoring to demonstrate by statistical 

 methods that natural selection is actually at work among human 

 beings and to obtain a measure of the intensity of its action. 

 From data on the general health of professional classes which were 

 exposed to much the same environmental influences, Pearson 

 found a parent-offspring correlation of .3824 which is indicative 

 of a fair amount of hereditary resemblance. Longevity was found 

 byBeeton and Pearson to run in families as has long been believed 

 and as in fact common observation seems to show. In selected 

 groups such as the British Landed Gentry and the Peerage where 

 environmental differences play a relatively small r61e, a marked 

 correlation was found between the length of life of father and son 

 and also between the length of life of brothers. Great length 

 of life was also found to be correlated with increased fertility. 

 It is, of course, obvious that up to the end of the reproductive 

 period, the longer people live the more children they may be 

 expected to have. But the fact that the longer women live after 

 their reproductive period the more children they are likely to have 

 in this period indicates that increased fertility and longevity are 

 both the result of a high degree of vitality. " Of two women who 

 both lived beyond 50 years, the longer lived is likely to have had 

 before 50 the larger family." (Beeton, Yule and Pearson.) 



Similar results were obtained by Powys from data obtained 

 in New South Wales. Fecundity was found to increase in women 



