44 ESSAYS OF A BIOLOGIST 



means of speech, writing, and printing, he has devel- 

 oped a new mode of inheritance.^^ Each community, 

 and indeed humanity as a whole, transmits its pe- 

 culiarities to later ages by means of tradition, using 

 that word in its largest sense. Physical inheritance 

 of the same type as in all higher animals and plants 

 is the necessary basis, but the distinctive characters 

 of any civilization are based on this new tradition- 

 inheritance. Thirdly, the type of mind which has 

 been evolved in man is much more plastic — a much 

 more elastic and flexible mechanism than any tool 

 previously evolved by life for handling the problems 

 of existence. As a consequence of this we have the 

 substitution of general educability for specific in- 

 stincts. For the power of performing comparatively 

 few actions smoothly and without trouble, there is 

 exchanged the possibility of a vastly increased range 

 of action, but one which has to be learnt. As an- 

 other consequence, man has come by the power — im- 

 possible to any other organism — of leading what is 

 to all intents and purposes a multiple existence. It 

 is for this very reason difficult to fit man into many 

 of the ordinary biological categories. The physical 

 and mental structure and the mode of life of even 

 the highest of the animals are for all practical pur- 

 poses a fixed quantity. An ant, for all its delicacy 

 of adjustment, is little less than a sentient cog shaped 

 to fit in just one way into the machinery of the com- 

 munity; a dog, for all his power of learning, is tied 

 down and imprisoned within a rigidity and narrow- 



10 See Carr-Saunders, '22. 



