THE INHERITANCE OF DURATION 153 



sweep in their passage over the span of life as has the 

 general population life curve discussed in the preceding 

 chapter. The descent is a little steeper in early adult 

 life. The female curve diifers in two respects from the 

 normal general population curves. In the first place, 



O 'I I I t I I I L^J I I \ I I I I I I ^>~--^ 



B 5 10 15 ZO ZB 30 35 40 -tS 50 is 60 65 TO 7S SO as 90 9S 



A6E 

 Fig. 41. — Showing survival curves of members of the Hyde family (Plotted from Bell's data). 



beginning at age 15 and continuing to age 90, the female 

 curve lies below that for the males, whereas normally for 

 the general population it lies above it. This denotes a 

 shorter average duration of life in the females than in 

 the males, the actual figures being 35.8 years for the males 

 and 33.4 years for the females. Bell attributes the dif- 

 ference to the strain of child-bearing by the females in 



