I9 2 Dynamic Evolution 



a generation reproduces a little later than 

 previous generations, then that part of the 

 next generation which survives to reproduce 

 will live a little longer than the present 

 generation and at the same time will have its 

 reproductive period extended. If the next 

 generation utilizes its additional time to repro- 

 duce still later, then the third generation will 

 live still longer and have its reproductive 

 period come still later. If the successive 

 generations are lethargic, then we have in- 

 creased length of life without noticeable 

 increase in mental energy, as in the tortoises. 

 If the successive generations are active, then 

 that activity concentrates energy in propor- 

 tion to the degree of activity and the length 

 of time employed, and we have steadily 

 increasing mental power, as in man. 



Limit? There is no known limit nor are 

 there present indications of one. Man lives 

 much longer than many mammals to which 

 he is said to be a distant blood relative, and 

 during the past his length of life has been 

 gradually extended. The same processes 



