180 Dynamic Evolution 



division has been reduced in the parent, the 

 result should check the rate of cell division 

 in the offspring. As the rate of cell division 

 becomes gradually less and less as the indi- 

 vidual grows older, this means that, within 

 limits, the older the parents are at the time 

 of reproduction the greater should be the 

 longevity of the offspring. 



The investigation which follows was made 

 for the purpose of testing the accuracy of this 

 deduction as applied to human beings, and 

 the records used were the genealogies of early 

 New England Families. These genealogies 

 are human herd books in which are recorded 

 the dates of births, marriages, and deaths of 

 all individuals in certain groups for several 

 generations. A primary consideration in 

 using these books for this purpose is the selec- 

 tion of proper material. Obviously, the best 

 material is that which represents the rela- 

 tive longevity of brothers and sisters, and 

 the larger the families in which we find these 

 brothers and sisters the better is the material. 



At this point it is proper to mention that 



