MAN : HIS GEOGRAPHICAL RELATIONS. 61 



dowed. It is true the ranges of certain groups may 

 suffer no perceptible change for ages, yet no truth in 

 geology is more thoroughly established than that every 

 portion of the earth's surface is, and has been, subjected 

 to variations ; and hence we naturally associate ex- 

 ternal conditions and vital changes, whether of dis- 

 tribution or of character, in the way of cause and 

 effect. It is by no means contended that external 

 conditions are the sole causes of vital variation, but 

 merely aflirmed that they are important and obvious 

 causes, and, as such, must ever be taken into account 

 in all our reasonings on the diversity and distribution 

 of plants and animals. Like the lower animals, man 

 is also amenable to the influences of food and climate, 

 but being possessed of the power of clothing himself, 

 of storing up food, and of using fire, he has acquired 

 an almost cosmopolitan range — few tracts of the earth 

 being untenanted by him, save the snow-clad mountain- 

 tops or the ice-bound solitudes of the polar regions. 



Though having a wider range than other animals, 

 and less influenced by latitude and altitude, man in 

 all his relations — physical, social, and industrial — is 

 stiU intimately affected by his geographical surround- 

 ings. Under the tropics, where warmth and the 

 means of subsistence are easily procured, he is chiefly 

 a vegetable-feeder, improvident and little progressive ; 

 under temperate latitudes, where the means of sub- 



