THE UNIQUE MAMMAL 21 



adaptability be justly appraised when he persists in making 

 himself an environment demanding only a minimum of true 

 biological adaptation? 



In the case of "civilized" man achievements in environment- 

 making need no emphasis. Manifold examples are everywhere. 

 He modifies the earth, air, and water of his world to his use. 

 He alters to his wishes and needs, in greater or less degree, the 

 plants, animals, and men with whom he makes contact im- 

 mediately or remotely. The activities comprised within the term 

 "public health" furnish perhaps the most impressive example. 

 By his alterations of the environment to this end man has added 

 something of the order of a quarter to a third of a century to 

 his average duration of life in a relatively short period of his 

 history as a species. 



I shall stop at this point and continue the discussion of man 

 as the unique mammal in the next lecture. 



