146 SOCIAL HEREDITY AND SOCIAL EVOLUTION 



geese, pigeons, sparrows, crows, partridges, quails, 

 gulls, etc., are well known. Indeed, the tendency to 

 associate is so widely distributed among birds as to 

 be well-nigh universal. Some species, it is true, are 

 commonly unsocial, but even these, like eagles, buz- 

 zards, etc., form temporary associations. Some 

 which, like marine birds, seem to have no special 

 interest in each other, occasionally combine in great 

 numbers for common defense. Others, like the 

 swans, although seeming to take no special interest in 

 each other, nevertheless form societies which exclude 

 all strangers. Most birds, however, form associa- 

 tions where there is a manifested pleasure in each 

 other's company, and in some cases, like the parrots, 

 they form great societies and station sentinels for 

 guards. In this instance there is a semblance to 

 actual organization and a clear advance toward 

 society. 



The mammals are, however, the most interesting 

 for our purpose. Here we find all grades of organ- 

 ization. Among the lowest of them no societies 

 whatever are formed. This is true of the Monotre- 

 mata, Edentata, Insectivora, and most of the Mar- 

 supialia. Among the Eodentia, while some live soli- 

 tary lives, many live in companies. Rats and mice 

 frequently form societies, and rabbits in the same 

 way associate together. Marmots and prairie dogs 

 live in communities, and the wonderful colonies of 

 beavers are proverbial. Marine animals, like whales, 

 dolphins, porpoises, live almost universally in 

 schools. Carnivora, which are in general flesh hunt- 

 ers, do not ordinarily show a tendency to form 

 societies. Their kind of life is, in general, calculated 

 to prevent individuals from living in companies, 



