346 ANIMAL AGGREGATIONS 



young separate each night and come together one by one to form a 

 group as the Hght increases the next day. Further, the group does 

 not keep its original character of being made up of the young of one 

 male ; but the groups readily mix, either by the fusing of two sepa- 

 rate groups or by the junction of individuals with groups with which 

 they have not previously had acquaintance. In both cases, the 

 group, once formed, is fully as well integrated as though all belonged 

 to the original family, and shows a high degree of group protection, 

 particularly through the multiplicity of eyes, which may detect 

 danger, and the transmission of stimuli, which lead to quick separa- 

 tion and flight. The members of the group are safer than if they 

 swam alone. This case is the more instructive since the group re- 

 forms daily, and since, as Bowen has shown, the coming-together 

 is largely conditioned by the possession of a weak social appetite 

 combined with certain reciprocal reflexes. 



These illustrations suggest the possibility of the formation of 

 groups of decided social integration as the result of the congregation 

 of individuals, without a family aggregation of any sort appearing 

 in this particular type of organization. 



Social organizations among birds include phenomena of leader- 

 ship, of group integration, of division of labor, at least to the estab- 

 lishing of sentinels, of joint action in common defense by spreading 

 an alarm and by joint attacks, so that we are warranted in ranking 

 them as well-developed social groups. Even so, we repeat, they 

 may arise from the congregation of individuals as well as by the 

 coming-together of families. In so emphasizing the possible social 

 development from the aggregations of individuals with which this 

 book is mainly concerned, I have no intention of underestimating 

 the other well-known method of social development by the extension 

 of the family type of aggregation, which may be seen in process of 

 development among the solitary wasps and which comes to a high 

 state of perfection in the social wasps, bees^ ants, and termites. 



Students of human sociology are generally agreed that our com- 

 plex modern social organization rests primarily on family groups 

 (Thomas, 1909; Lowie, 1920; Malinowski, 1927). Miller in 1928 

 reviewed a part of the literature appearing just preceding that date 



