272 Heredity and Environment 



are known from many remains, implements and handiwork, as 

 well as from certain primitive races or tribes which have per- 

 sisted to the present time. The grades of culture represented by 

 these extinct or persistent tribes and by modern men are usually 

 classified as savagery, barbarism and civilization. There must 

 have been much greater evolution of human types during pre- 

 historic times than since the beginnings of civilization. The 

 physical, mental and moral changes which took place in men from 

 the earliest stages of savagery down to the beginnings of civili- 

 zation were very great, but they were nevertheless slight com- 

 pared with the tremendous changes which must have occurred in 

 those long ages before the ancestors of man actually became men. 

 Within the historic period the evolutionary changes in man have 

 been very small. Minor changes have occurred and are still going 

 on, as Osborn has shown in his "Cartwright Lectures on Contem- 

 porary Evolution in Man," but the species has remained relatively 

 stable during the historic epoch as compared with the much longer 

 prehistoric period. 



The past history of man has been a long one, no one can say 

 how long, but probably not less than half a million years have 

 passed since the genus Homo appeared, and not less than one 

 hundred thousand years since the present species arose. There 

 is every reason to believe that the future history of man will be 

 even longer. Barring great secular changes, catastrophies or 

 cataclysms, which cannot be foreseen nor provided against, man 

 controls his own destiny on this planet. 



It is a curious fact that in prescientific times the instability of 

 nature especially appealed to men. How often in the past have 

 men looked forward to a "speedy end of the world" ! It may 

 well have seemed to our ancestors a useless thing to take any 

 thought for the morrow if very soon the heavens are to be rolled 

 up as a parchment and the elements dissolved in fervent heat ; it 

 would be folly to plan for future ages if the time is at hand when 

 the angel shall stand with one foot on the sea and the other on 

 land and declare that time shall be no more. But science has 





