Evolution of Intelligence 77 



four years added to the age of the parent when 

 the child was born, added one year to the normal 

 longevity of the child. The actual table is as 

 follows : 



Expectancy of Life at Age of 25 for 1,105 Brothers 

 and Sisters of Composite Family. 



Average 

 Age of 

 Ages of Fathers at No. of Childen at 



Birth of Children Children Death 



Under 25 83 62.63 years 



25 to 29 233 65.20 years 



30 to 34 266 65.28 years 



35 to 39 199 65.41 years 



40 to 44 165 68.02 years 



45 to 49 88 66.28 years 



50 and over 71 70.27 years 



1105 65.89 years 



There can be no doubt that lengthening the 

 time from birth in one generation to birth in the 

 next adds to the longevity of the descendants, 

 but the figures given must be considered as ap- 

 proximate only. There is a high degree of prob- 

 ability that the approximation is pretty close, but 

 to determine the matter accurately would require 

 a more extended investigation, and one extend- 

 ing over several successive generations. This 



