134 HUMAN BIOLOGY 



the mastery of environment, may it not be that language 

 is his most important single behavioral achievement, and 

 that human supremacy is due to linguistic facihtation 

 of thought and intercommunication? Probably the common 

 ancestor of ape and man used symbols very simply and 

 seldom, if at all. The human hne of descent tended toward 

 linguistic development, which in turn furthered the accumu- 

 lation of a vast body of social tradition. The ape line, 

 tending by contrast toward the utiHzation of bodily attitude 

 instead of vocahzation to express emotion and idea, pro- 

 gressed more slowly, haltingly, and without the accumula- 

 tion of racial tradition or notable mastery of environment. 



This possible general contrast between the distinctively 

 human and non-human directions of primate evolution 

 deserves further consideration, because it appears that 

 survival of a type, its geographical distribution, and its 

 multiplication, are conditioned very largely by its ability 

 to control environment. While the apes were struggling 

 to adapt themselves to unpredictable variations of climate 

 and food supply and failed or succeeded, diminished or 

 increased, in accordance with circumstances wholly beyond 

 their control, early man imagined and wrought for himself 

 protective coverings and shelters from heat and cold, 

 from sun and storm, so that he might live almost anywhere 

 on earth, whereas other primates were restricted by climate 

 and food supply to certain limited areas. Where they per- 

 ished miserably from starvation due to drought, flood, 

 or devastating storms, he has sown and reaped, with fore- 

 sight accumulated and stored supplies, and multiplied 

 both sources and varieties of natural and artificial prod- 

 ucts, until largely independent of environmental accidents. 

 It appears that during the era of differentiation of man 

 from other types of man-like ape, progress by self-knowl- 

 edge and self-adaptation was more narrowly limited and 

 offered fewer opportunities for discovery and ingenious 

 control than did the molding of environment or mutual 

 adjustment of self and environment. And the result, not 

 yet completely achieved, although clearly indicated in its 

 trend, and reasonably predictable from the present status 

 of primates on the earth, is the failure of the man-like 



