370 ELEMENTARY ZOOLOGY. 



lived. Clothes, houses, cities, fire, seasoned foods, stim- 

 ulants are terms which suggest some of these artificial 

 elements that have entered into man's life. Just what 

 their final effect will be on the body and mind of man no 

 one can tell. Many of the most terrible diseases to which 

 man is subject are the diseases of civilization. That 

 his wits will continue to enable him to meet the new 

 problems which he brings on himself, as he has met the 

 natural ones, we may well believe. But unquestionably 

 we must realize that his greatest task is to use his increas- 

 ing mastery of nature in meeting the new difficulties 

 which his own complex and artificial civilization is bring- 

 ing upon him. 



364. The Age of Man on the Earth. There is no sure 

 knowledge of when man, in his present form, first appeared 

 on the earth. It is known that man lived in Europe in 

 the later portion of the Ice Age, and quite probably earlier. 

 His implements of stone are found along with the remains 

 of such animals as the cave-bear and mastodon and man- 

 like apes, either extinct now or found only in tropical 

 regions. The oldest of these human remains are found 

 in southern Europe and in northern Africa. We have 

 signs of the gradual improvement of his stone implements 

 from rough to smooth; the introduction of other material 

 as bone and, later, copper, bronze, and iron. It is only 

 after the thousands of years of this primitive, unrecorded 

 history that we come to the history of such well separated 

 nations as those of the Euphrates and Nile valleys, whose 

 monuments and inscriptions are believed to take us back 

 6,000 years or more. 



365. The Principal Types of Men and Their Distribu- 

 tion. It is not perfectly certain that all the men of to-day 



