248 THE SOCIAL LIFE OF ANIMALS 



has already been listed. This states that only those 

 groups which have grown out of the persistence of 

 sexual and more especially partial or completely 

 familial relations are truly social. This point of view 

 has been touched upon with some sympathy in the 

 first chapter. There is an important relationship 

 which underlies this definition; many highly organ- 

 ized social groups do develop from the continuation 

 and extension of family ties. But though this con- 

 dition has given rise to many of the better devel- 

 oped social units, care must be taken not to regard 

 its presence as the essential difference between the 

 social and the sub-social. As Professor Child (32) has 

 suggested, boys' gangs, girls' cliques, and men's and 

 women's clubs present difficulties to one who wishes 

 to define all societies as extensions of familial rela- 

 tionships. It is quite possible to regard such social 

 phenomena as expressions of other aspects of the 

 social urge which have developed independently of 

 paternal or fraternal interactions. There are counter- 

 parts of these human groups among other animals, 

 as well as counterparts of the extensions of family 

 life. The overnight aggregations of male robins, the 

 long-continuing stag parties of male deer outside the 

 short rutting season, (38) the flocks of mixed species 

 of birds common in tropical regions (Beebe tells of 

 one made up of twenty-eight individuals represent- 



