14 FARM ANIMALS 
but the individuals of the species. As the crowding in- 
creases the warfare becomes more intense, and this re- 
mains until the natural balance obtains again. If the 
seasons are unusually severe or the enemies gain in 
strength, some certain species may altogether disappear. 
This always follows if the death rate exceeds the birth 
rate. Only those species increase that are favored by 
strength or environment. 
“Tt is said that at the time of the discovery of America there were 
no more red men than live today. The severe struggle for food led 
to war and disease, which in turn maintained the balance between 
the consuming population and the production of wild animal life 
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CROWDING OF ANIMALS LEADS TO WARFARE 
At one time immense numbers of American bison inhabited the vast areas of the 
western plains. Why have these animals disappeared ? 
available for human food. When the number of Indians in a tribe 
increased, more animals were slaughtered; to meet these new de- 
mands it was necessary to search for food at further distances and 
in new territory, often the property of another tribe. War usually 
followed, and in the thinning of the ranks of both contestants, the 
slaughtering of game was lessened, which continued until the sup- 
ply of game or animal life was equal to the ability of plant life to 
support it or until the increase of Indian population again caused 
depletion to the minimum numbers.” 
