98 PHYSICAL BASIS OF CIVILIZATION 



of creatures which have really existed and have been 

 exterminated by man. 



Many instances are credibly reported since historic 

 times when certain districts were, for a decade or 

 two, stripped of all human population, and later 

 found overcrowded with many kinds of wild mamma- 

 lian brutes. 



Because it is not true, therefore, can it not be 

 fairly objected, to a small and unimportant part of 

 the above argument, that cats, which have caught 

 mice, sometimes show as cruel a disposition as man. 

 Whenever cats hunt mice they are moved thereto 

 by the primary instinct of a carnivorous animal. 

 The playing of the cat with the mouse before killing 

 it is obviously the artificial result of domestication, 

 which supplies the cat with more than enough food 

 to satisfy hunger, and yet cannot abolish the pri- 

 mary instinct which makes her catch mice. Then 

 domestication cultivates in the cat the desire for 

 human approbation, and to obtain this she shows 

 off her pranks with the live mouse. Besides, a cat 

 has not the intelligence which would restrain cruelty 

 by a sense of the suffering inflicted. 



To recapitulate: The natural enemies and com- 

 petitors of man's brute ancestors were all so well 

 supplied with means of offence, defence, protection, 

 escape, and multiplication, that the ordinary natural 

 agencies which tend to keep life within bounds were 

 insufficient to prevent their increase to the extent 

 of crowding the area over which our early progeni- 



