168 M: .M Beeton, Mr. C. 1". Yule and I'n.f. K. I', Mi-son. 



factor of evolution. The English results on the other hand show us a 

 small but sensible tendency in reproductive selection to prolong the 

 duration of life. Allowing three generations to a century, we might 

 expect the duration of life to be raised about 2 years in a century 

 by this factor of evolution. 



In making this statement we are supposing that parents are not a 

 short-lived selection out of the general adult population. There 

 seems no reason why they should be, and we have some statistics to 

 show they are not. Thus for the ' Peerage ' and ' Landed Gentry ' we 

 have shown that for fathers and sons living 20 or 25 years and upwards, 

 the age at death of the father is substantially greater than that of the 

 son.* Further, from data for the Society of Friends, Miss Beeton has 

 found the average age at death of women in general to be 59*831, and 

 the average age of mothers at death to be 59*793, sensibly the same. 

 In the table for 1871 to 1880 given by the Registrar-General, the expecta- 

 tion of life of women in general at 20 years of age is given as 41*66 years, 

 or the average duration of life is 61 '66 years. This is only very slightly 

 greater than our average! for English mothers above, i.e., 61*183, and 

 substantially less than our average for mothers weighted with their 

 offspring, i.e., 63*082 years. Again, the general population of males of 20 

 had (187 1-80 returns) an average life of 64*48 years, which is not com- 

 parable with our ' Landed Gentry's' sons surviving 20 with an average 

 life of 60*915 years, but with that of their fathers, i.e., 65*96 years. We 

 do not think, therefore, that parentage, in particular maternity, corre- 

 sponds to any shortening in the expectation of life. Thus reproductive 

 selection appears to indicate a real increase in the expectation of life. 

 Such an increased expectation of life is usually considered to have come 

 into existence during our century owing to better sanitary conditions, 

 greater care of the sick and invalided, &c., &c. Its exact estimation is a 

 matter of some difficulty. \Ve find F. G. P. Neison,| working on the 

 Registrar-General's returns before 1841, gives (Table D, p. 8) expecta- 

 tions of life from 10 years onwards. For males of 20 and 25, his mean 

 durations of life are 60*69 and 62*35 for females of 20 and 25, 61 *60 and 

 63*36 respectively. These are not substantially less than the Registrar- 

 General's returns for 1881 to 1890, which gives males 60*27 and 61*28, 

 females 62*42 and 63*50 respectively. In fact, the males show reduc- 

 tion. If we stick to the Registrar-General's returns as given for three 

 different periods, and presumably more comparable with each other 

 than with Neison's work, we have the following results : 



* ' Roy. Soc. Proc.,' vol. 65, p. 297. 



t The average age at death of mothers must in our case closely give the expecta- 

 tion of life of women of 20, for there are few marriages below 20, and we have in 

 our tablet included all cases of sterile unions. 



J ' Contributions to Vital Statistics,' London, 1846. 



