348 ANIMAL AGGREGATIONS 



constituted by temporarily associated families. The transition from 

 pronounced gregariousness to family life seems to occur between 

 gibbon and chimpanzee. 



"Leadership, the dominance of one individual, and variation in 

 social value and influence in accordance with individual traits, ap- 

 parently tend to become increasingly important from lemur to man. 

 The transition is from the leader of the herd to the patriarchal head 

 of the family. 



"Likewise, sociabihty and social dependence, in certain at least, 

 of their social aspects tend to increase from lemur to ape, but so 

 does individualism; and whereas the chimpanzee is extremely soci- 

 able and dependent therefore upon its social environment, both 

 orang-outan and gorilla are markedly less so than are certain mon- 

 keys and lemurs. Obviously knowledge does not permit of safe 

 generalization. With respect to mutual aid and like expression of 

 sympathetic interest there can be no doubt of marked increase: 

 lemur, monkey, ape, man. 



"Permanency of mating, although not definitely established for 

 any infrahuman primate, is rendered increasingly probable from 

 lemur, through monkey, to ape, by the nature and abundance of 

 pertinent evidence. The same may be said of monogamy, for al- 

 though it may exist in any of the four groups which we are comparing, 

 so also, according to pertinent observations, may polygamy. Wheth- 

 er there is definite phylogenetic tendency toward the one or the 

 other type of family it is impossible to say. But in any event the 

 family as a social unit seems to become more prevalent and also 

 more stable as we progress from lemur to man." 



Men have other aspects of group life in common with these non- 

 human anthropoids. Thus the monosexual human gangs and 

 clubs seem to have their counterpart in the sleeping group of male 

 gibbons which Spaeth (see Yerkes, 1929) found in the Siamese 

 jungle. Such human and gibbon behavior appears to be an expres- 

 sion of the widespread phenomenon of the formation of monosexual 

 groups which have been recorded notably among various other 

 mammals (seals, for example), among birds, and among the so-called 

 solitary bees and wasps. As in man, the young orang-outans con- 



