Correlation and Application of Statistics to Problems oj Heredity 117 



woman would have on the average 473 nephews and 5'12 nieces. The later 

 generation seems to give a slightly smaller family than the earlier genera- 

 tion. Since the families include only those who have reached adult age, and 

 the infant death-rate was certainly greater in the older generation, the decrease 

 in size of family is probably larger than appears. The calculations show that 

 an individual has on the average about one fertile relative in each specific 

 type of kinship. Galton now says that he proposes to make "the reasonable 

 and approximate assumption" that "the number of fertile individuals is not 

 grossly different to that of those who live long enough to have an opportunity 



of distinguishing themselves" "Thus if a group of 100 men had between 



them 20 noteworthy paternal uncles it will be assumed that the total 

 number of their paternal uncles who reached mature age was about 100, 

 making the intensity of success as 20 to 100 or as 1 to 5. This method of 

 roughly evading the serious difficulty arising from ignorance of the true 

 values in the individual cases is quite legitimate, and close enough for 

 present purposes" (p. xxxiii). 



The argument is not easy to follow. Galton, for example, has (p. xxx) 

 shown that the number of paternal uncles who survived childhood in the case 

 of 100 F.RS.'s is 228, and he now says we must consider this as only 100, 

 and so we see the above number reduced to less than one half. But I think 

 he is contrasting those who survived childhood with those who lived long 

 enough to have an opportunity of distinguishing themselves. He considers 

 that only one individual in each grade of kinship can on the average be 

 fertile in a stable community, and such an individual would probably live to 

 an age at which he would have had an opportunity of distinguishing himself. 

 But it is difficult to see why those who have an opportunity of distinguishing 

 themselves are limited to the fertile. The unmarried uncle may equally with 

 the married have a chance of distinguishing himself. Assuming that "survived 

 childhood" meant to the Royal Society Fellows the surviving 15 years of age 

 — and Galton refers to competitive success at school — and that by 40 years 

 any man has had an opportunity of distinguishing himself, then only some 

 £ of those alive at 15 are dead before 40. Thus our 228 paternal uncles 

 would scarcely be reduced to 182 if they had died at the rate of the total 

 average community. Probably their lives were considerably better than the 

 average, and it would be safe to suppose nearly 200 lived to forty years. This 

 is 100 °/ more than Galton proposes to take. I should therefore be prepared 

 to double Galton's number of candidates for distinction in each collateral 

 grade of kinship* (but this will not affect his conclusions, if we are discussing 

 only relative, not absolute degrees of noteworthiness) and to suppose the same 

 number of relatives in each grade, which is approximately true (see our p. 107). 



In Chapter VIII Galton limits his inquiry to males. He says that: 



"Women have sometimes been accredited in these returns by a member of their own family 

 circle, as being gifted with powers at least equal to those of their distinguished brothers, but 

 definite facts in corroboration of such estimates were rarely supplied." (p. xxxiv.) 



* This does not apply to the direct line, in which the number who lived to bear offspring is 

 known exactly. Of course any direct ancestor may have died without reaching the age when he 

 could obtain noteworthiness, but Galton does not consider the effect of this. 



