From Savagery to Civilization 63 



Man needs a habitation of some kind. In a 

 warm climate a tent or cheaply constructed hut 

 or house serves every purpose. In a cold climate 

 a man must, or usually does, build a more sub- 

 stantial house to protect himself in winter. This 

 more substantial house requires more mental ef- 

 fort in planning and more physical labor to 

 construct. 



In a warm climate man needs fuel only for 

 cooking purposes. In a cold climate a man must 

 provide fuel to warm his house in winter, and 

 that requires extra effort on his part. In a 

 warm climate a man needs but little clothing. 

 In a cold climate a man must provide extra 

 clothing for winter protection, and providing this 

 extra clothing demands extra labor. And so on 

 for many things. The people who live in cold 

 climates must and do exert themselves mentally 

 and physically to a much greater extent than do 

 those people who live in warm climates. 



When a man goes into a gymnasium and 

 swings Indian clubs and dumb bells, he exercises 

 certain muscles, and those muscles gain strength 

 as a result of the exercise. The fact that mus- 

 cles gain in strength as the result of exercise is 



