stable life communities, we often overlook the close interdependence among 

 all the species. We are especially likely to overlook the smaller plants and 

 animals in the soil or in dark corners — just as we often overlook the obscure 

 parts of a human population when we travel about, and judge a community 

 or a civilization by some conspicuous features. 



It is of course reasonable for us to cut trees for our use or to capture animals 

 for their furs or to catch fish for food. Like other things, we have to get from 

 nature what we need. And timber, food, fur, are the values that we see in 

 these various life communities. It should be clear, however, that in a stable 

 life community, in nature as well as in a human civilization, no individual and 

 no species can live by itself — nor, very long, for itself. Each can live only as 

 a member of the larger group, and this group continues only as its essential 

 members maintain a due balance of numbers and of activities. 



Is Man a Member of a Natural Community? 



Man an Interloper Man is apparently a late arrival among the many 

 species of living things, in a world already old. We can hardly suppose that 

 he had a place all ready and waiting for him. Like other species, he must have 

 had quite a struggle to make a place for himself. But where? 



Today man is more widely spread over the face of the earth than any other 

 species, except the simplest water-dwelling animals. We must except also the 

 parasites that man has taken with him, and some of the domesticated animals, 

 especially the dog. Man today finds himself at home in the tropical jungle 

 and amid the arctic snows, in fertile river valleys and on relatively dry pla- 

 teaus, along the seashore and in the mountains, in forests and on the open 

 plains. 



Always, however, man could migrate only into regions that had already 

 established an equilibrium of plants and animals. For only there was there 

 a sufficient variety and sufficient number of living beings to supply him suffi- 

 cient food and sufficient materials for shelter against the weather and against 

 dangerous animals. 



Man the Wanderer The spread of the human species to nearly all cor- 

 ners of the earth took many thousands of years. It is only in recent centuries 

 that the human population seems to have increased rapidly. And only in 

 modern times has it been possible to observe closely the processes by which 

 man extends his sway over the earth. The earliest settlers from Europe in 

 North America found small encampments of Indians occupying but sparsely 

 a vast forest on very good land. As these new arrivals from Europe all came 

 from crowded regions, everybody eagerly reached out for as many acres as 

 possible. Very often they seized many more acres than they could ever use. 

 One result was that after the first colonies had become fairly well established 



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