1912.] 



The Intensity of Natural Selection in Man. 



475 



Thus in the case of females the child death-rate goes down about 1 per cent, 

 for every rise of 1 per cent, in the infantile death-rate. 



As we have seen, the correlations are not as high in the case of the females 

 as in that of the males. This is probably, to some extent, due (i) to the ages 

 of the women being less reliable than the ages of the men, and this would 

 affect e, and (ii) to the lower infantile death-rate in women, the selection 

 being very likely pushed to a higher age ; the mere difficulties of birth are 

 greater in the case of the boy and selection may thus be more immediate and 

 stringent in his case. The lower values of the correlations make the 

 agreements between observed and calculated values less close, still there is 

 nothing much to complain of here : — 



Observed. 



1838—1854 .. 

 1871—1880 .. 

 1881—1890 .. 

 1891—1900 .. 



119 -86 

 103 -55 

 87 -98 



The remarkable feature of these English life-tables has been the falling 

 child death-rate accompanying the rising infantile death-rate, a phenomenon 

 which should have led those who assert that a high infantile death-rate 

 implies a high death-rate in the next four years of life to pause. It is note- 

 worthy that the Kegistrar-General has drawn up life-tables in six cases for 

 " selected material," i.e. for " selected healthy districts."* These tables give 

 the following results : — 



1849—1853 

 1881—1890 

 1891—1900 



53-94 

 56-37 

 57 -52 



92 -64 



93 -50 

 95 -08 



Without venturing to work out anything on the basis of' two sets of three 

 tables, we can yet recognise from the crude numbers that precisely the same 

 phenomena occur even in the " healthy districts," i.e. improving environment 

 is related to an increasing not a decreasing infantile mortality and while the 

 child mortality decreases with better conditions, it is highly correlated in a 

 negative sense with infantile mortality, a correlation which will not be 



* 1 Supplement to the 65th Annual Eeport,' Part I, pp. lviii — cxi, 1907. 



