78 SOCIAL HEREDITY AND SOCIAL EVOLUTION 



manner whicli can have no meaning to liim. From 

 his standpoint there is certainly no reason for his 

 yielding his own interests and comfort for the un- 

 born generations of which he has no knowledge. 

 This sacrifice of self has sometimes been called altru- 

 ism. But among animals it does not properly 

 deserve this name, since it is wholly unconscious, and 

 genuine altruism must appreciate its sacrifice. While 

 the struggle for self-interest is sometimes a conscious 

 one, this struggle for the good of the race is commonly 

 unconscious. Most animals that sacrifice so much to 

 their posterity never see their offspring and know 

 nothing about them, commonly not even knowing the 

 possibility of their existence. They yield to blind 

 instinct, not to reason. The salmon is not drawn 

 into the river because she feels it is the best place to 

 deposit her eggs, for she never sees her young which 

 hatch long after she may be dead. She faces the 

 danger of the river because she is driven by an irre- 

 sistible impulse which though not understood is 

 blindly obeyed. Such an impulse is an instinct, and 

 its origin must be included under the explanation of 

 the origin of instincts in general. It is significant to 

 note that the instinct that leads to the perpetuation of 

 species is the most imperative of all instincts. What- 

 ever sacrifices it demands are freely given. Among 

 low and high animals alike this instinct is ever lead- 

 ing to individual sacrifice, wholly inexplicable from 

 the standpoint of the individual, but readily inter- 

 preted from that of the race. Among insects the 

 yielding to the instinct may lead to exhaustion and 

 death, and even in man the sexual instinct has always 

 been one of the most potent influences in society. 

 Since this sacrifice of individual interests to the 



