CHAPTER IX 

 BUILDING MATERIALS, THEIR USE AND ORIGIN 



All animals need some protection from the unfavorable fea- 

 tures of the weather and from dangerous enemies. Man has 

 even less ability to endure unprotected the extremes of climate 

 or to resist by his muscular strength alone the attacks of his 

 foes. Through his intelligence, however, he has made his life 

 more secure than that of any other animal species. 



187. Primitive shelter. In the very early ages, man found 

 shelter from storms and from extreme heat or cold under trees 

 or in fireless caves. He avoided dangerous animals by climb- 

 ing trees. Later he learned to construct rude habitations of 

 branches, bark and leaves, grasses, and stone. These dwell- 

 ings afforded him many advantages not to be had in caves or 

 other natural shelter. For purposes of better defense against 

 enemies these dwellings were often built close together; and 

 by living in villages primitive men learned the value of working 

 together or cooperation in many pursuits. 



188. Permanent buildings. After a while men ceased to be 

 nomads and settled down to the cultivation of the soil and to 

 tending their flocks and herds. Then they began to build with 

 an idea of permanence and greater protection against foreign 

 enemies. They made use of minerals and hewn timbers for 

 building materials. In the fertile valleys of the Tigris, the 

 Euphrates and the Nile where the population multiplied rapidly, 

 such a change in mode of living and building came compara- 

 tively early. 



Dwellers along the Nile found stone useful for their pur- 

 poses. Their engineers made use of blocks of stone of tre- 



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