148 SOCIAL HEREDITY AND SOCIAL EVOLUTION 



that animals understand enough to realize why they 

 thus unite. They obey a blind impulse to act to- 

 gether; they act from simple instinct, and then 

 the advantage thus afforded by unity of action 

 preserves those animals which have such social in- 

 stincts. Beyond doubt, however, another impulse 

 often underlying these societies is the mutual pleas- 

 ure in each other's company, which we call the social 

 instinct. That this social instinct is widely distrib- 

 uted among the higher animals is very evident. The 

 birds and higher animals most clearly find great en- 

 joyment in each other's society. Indeed, it is only 

 among the social animals that we find any especial 

 evidence of enjoyment in life. Social birds sing, 

 social mammals play, and such habits, which are our 

 chief indications of enjoyment among animals, are 

 confined to those animals among which the tendency 

 to form societies is best developed. While we must 

 recognize that the added strength which comes to a 

 band of animals from their unity explains the preser- 

 vation of such habits, we must also recognize that the 

 impetus that leads to their formation is most com- 

 monly the social instinct which causes one individual 

 to take pleasure in the company of another. 



The Expansion of the Human Family The lowest type 



of the human family, as exhibited by savages, and 

 hence probably by primitive man, is perhaps only 

 a slight advance over that found among some an- 

 imals like birds. With some human races organiza- 

 tion has not progressed beyond the stage of the 

 family. Among the Eskimos, for example, there 

 are no such things as tribes or villages, no laws, no 

 chiefs or leaders, but each family is quite independ- 

 ent. Practically the same conditions exist among the 



