IN THIS PAPER ON HUMAN EVOLUTION 



I want to stress the biological history of those 

 qualities which are really most distinctive of man 

 as an animal. The most important thing about man is the way 

 he behaves. Every man knows that man is an intelligent ani- 

 mal. Man's ability to make and use tools and his ability to 

 make and use symbols for communication are historically the 

 most important accomplishments leading to his present level 

 of intelligent behavior. These abilities have a biological basis. 

 Also, they go beyond that basis. The fact that man does com- 

 municate with symbols makes man different from everything else 

 on earth. 



This uniqueness has to do with symbols and their modes of 

 reproduction and inheritance. Symbolic reproduction and sym- 

 bolic inheritance depend on events that occur in the central 

 nervous systems of two or more individuals and not on events 

 that occur in gonads. We say communication takes place when 

 a signal produced by the sender alters the behavior of the re- 

 ceiver. But communication is called symboling when the sig- 

 nal has very special properties. As Langer (1942, p. 49) said, 

 "Symbols are not proxy for their objects, but are vehicles for 

 the conception of objects. To conceive a thing or a situation 

 is not the same thing as to 'react toward it' overtly, or to be 

 aware of its presence. In talking about things we have concep- 

 tions of them, not the things themselves; and it is the concep- 

 tions, not the things, that symbols directly 'mean.' Behavior 

 towards conceptions is what words normally evoke; this is the 

 typical process of thinking." 



Symbols are inherited in a different way than genes. It is 

 an unalterable biological law that new individuals (zygotes) 

 must inherit their genes— specific pieces of deoxyribonucleic 

 acid molecules— from other individuals that existed in the 

 past. The inheritance of symbols differs in kind. A grand- 

 father may take over and use, or misuse, symbols from his grand- 



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