86 ESSAYS OF A BIOLOGIST 



He can be specialized for several, or combine a high 

 degree of professional skill in one with the general- 

 ized knowledge of an amateur in another. It is this 

 obvious but fundamental fact which is at the bottom 

 of many of the failures to apply biological ideas to 

 sociology. 



Another human distinction is the increase of the 

 part played by environment in man as opposed to 

 animals (in determining his biologically effective 

 nature). Environment plays not merely a large 

 part, but a preponderating one, in his development 

 after the first year or so of his life. Tradition pro- 

 vides a special environment, made by man for man's 

 own development; and men brought up in markedly 

 different traditions arrive at different end-results just 

 as surely and obviously as do men of markedly dif- 

 ferent hereditary tendencies arrive at different end- 

 results even though exposed to similar traditions. 

 Traditions are infinitely complex things: there are 

 world traditions, national traditions broad and nar- 

 row, class traditions and traditions of profession and 

 trade, traditions of predilection, of art, of religion: 

 and men may be exposed in their development to the 

 combined influence of a number of these. But the 

 nett result of the diversity of tradition is an extraor- 

 dinary diversity of end-result. ''Nihil humanum 

 alienum a me puto" — Terence could only say this 

 with truth in the sense that there are certain funda- 

 mental emotions and instincts found in all men, and 

 also certain aspects of environment shared by all 



