398 HEREDITY AND ENVIRONMENT 



tion. There must have been much greater evo- 

 lution of human types during prehistoric times 

 than since the beginnings of civilization. The 

 physical, mental and moral changes which took 

 place in men from the earliest stages of sav- 

 agery down to the beginnings of civilization 

 were very great, but they were nevertheless 

 slight compared 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 evolution- 

 ary changes in man have been very small. 

 Minor changes have occurred and are still go- 

 ing on, as Osborn has shown in his "Cartwright 

 Lectures on Contemporary Evolution in 

 Man," but on the whole the race has remained 

 relatively stable during the historic epoch as 

 compared with the much longer prehistoric one. 

 The past history of man has been a long one, 

 no one can say how long, but probably not less 

 than 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 



