46 The Age of Parents 



and some old parents. A pedigree extended 

 that far and composed of all old parents or all 

 young parents is very rare. The terms "old" and 

 "young" as here used is somewhat vague, but 

 means a few years more or a few years less than 

 the average. The average in the white race is 

 about 32 for fathers when children are bom. If 

 we take five years above and below this as repre- 

 senting old and young, we may then say that it 

 is rare to find a pedigree in which all males in 

 three or four generations are either above 37 or 

 below 27 when the next generation is produced. 



The first step in this proceeding is to find the 

 normal distribution of births in normal pedigrees 

 in a normal community, and then compare that 

 with what is found in the pedigrees of intellect- 

 ually eminent men. The normal distribution was 

 determined by tabulating births as they occurred 

 in the 18th century in New England, and as they 

 are recorded in family genealogy. The table for 

 that is our standard for comparison. 



In the cyclopedias were found 571 eminent 

 men in whose pedigrees it was possible to get 

 dates of births for one or more ancestors in 

 each pedigree. A tabulation of the distribution 



