THE INHERITANCE OF DURATION 



157 



long-lived fathers which this group will have as com- 

 pared with shorter-lived individuals. 



Figure 43 shows the same sort of data for mothers 

 and offspring. Here we see the curve of great longevity 

 of parents rising in an even more marked manner than 

 was the case with fathers of offspring. The group of 



50 



30 



20 



10 



511 



PERSONS 



DIED 



-^o 



407 



379 



PERSONS 



DlLD 

 40-6O 



360 



PERSONS 

 DlLD 

 60-80 



148 



PERSONS 

 D/D 

 6O + 



50 



40 



30 



10 



40 60 80 - 4O 6O 8O - 4O 6O 8O - 4O 

 4O 6O 8O + 4O 6O 80 + 4O 6O BO + 4O 6O 



6O &O - 4O 6O 80 

 8O + 4O 6O GO + 



FIG. 43. Influence of mother's age at death upon longevity of offspring. First dot in 

 each diagram shows the percentage having mothers who died at 40; second dot the per- 

 centage having mothers who died at 40-60; third dot the percentage having mothers who 

 died 60-80; fourth dot the percentage having mothers who died 80+ (After Bell). 



offspring dying at ages under 20 had only 19 per cent. 

 of their mothers living to 80 and over, whereas the 

 group of offspring who lived to 80 and beyond had 41 

 per cent, of their mothers attaining the same great age. 

 At the same time we note from the dotted line at the bot- 

 tom of the chart that as the average age at death of the 

 offspring increases, the percentage of mothers dying at 

 early ages, namely, under 40, as given by the first dots, 

 steadily decreases from 17 per cent, at the first group to 

 just over 5 per cent, for the offspring dying at very 

 advanced ages. 



