THE CANNIBAL IN EVOLUTION 169 



It has been argued by Harry Campbell and others, 

 as I myself argued twenty-five years ago, that inter-tribal 

 warfare, in which all members of the tribe were engaged, 

 must have meant the rapid elimination of fools and the 

 unfit ; but so far it seems that it has not been pointed out 

 that the acts of war, whether tactical or strategic, tend 

 to develop all the logical and mental faculties of man. 

 Every human faculty has assuredly been called into exist- 

 ence by the stimulation of the environment. It does not 

 follow that every stimulation has brought out power to 

 deal directly with the situation. But it has certainly 

 developed powers of avoiding possible evil results, thus 

 moulding the race in another way. Certainly no faculty 

 can be conceived existing without need unless there is 

 in existence excess energy not wanted for self- or race- 

 preservation. For there are undoubtedly developments 

 not in themselves really useful. We cannot logically 

 attribute the gorgeous colouring of the Trochilidse purely 

 to sex selection, when we see the less gorgeous species still 

 highly adorned. We are forced to look on such super- 

 coloration as the result of excess energy in birds already 

 so energetic as to be almost beyond the ordinary accidents 

 of bird life, while they live on the most assimilable form 

 of carbohydrate. Such excess of adornment may in the 

 end become harmful to them, as it has done since debauched 

 destructive energy in rich women has demanded their 

 sacrifice for adornment. But if all useful faculties in 

 man, or any animal, must have been developed by the 

 stimulation of the environment we can, I think, conceive 

 no such stimulation as that of individual, group, and tribal 

 warfare for the purpose of obtaining the food which is the 

 most nourishing, and the most easily digestible of all. 

 Since it has already been humanized, it calls for less energy 



