SOCIETAL EVOLUTION 1 49 



The flocks, packs and herds of the higher vertebrates 

 constitute peculiar societies, quite unhke those of insects, 

 and might more properly be called peoples, populations or 

 "peuplades," to use Espinas' term. They may consist of a 

 number of associated famihes, of individuals of one or both 

 sexes or of the young only. They may be loosely or intensively 

 organized, temporary or more permanent, and either closed 

 or open, to use the classification of Alverdes, i.e. they may 

 either repel outsiders or admit them, even when they 

 belong to ahen species, and permit them to become members 

 of the society in good standing. Our knowledge of these 

 pecuhar organizations is far from complete, but some of 

 them have been recently studied with results that seem to 

 have important bearings on human societies, which are 

 really of the same fundamental structure. The peuplades 

 are held together by what has been usually called the gre- 

 garious, or herd instincts, but the investigations to which 

 I have just referred seem to show that the cohesion may be 

 due to more concrete and observable behavioristic factors. 



In their studies of birds, Schjelderup-Ebbe, Katz and 

 Fischel have shown that the flocks are organized according 

 to a pecuhar "pecking order," in which each individual has 

 its own status depending on whether it may peck other 

 individuals or submit to being pecked by them. To quote 

 Alverdes, "Schjelderup-Ebbe has shown how an order of 

 precedence comes into existence within societies. A flock 

 of fowls in a fowl run is not exclusive in the sense that its 

 members make common cause against a new arrival, leaving 

 the latter isolated. The new comer may safely attach itself 

 to the flock, but the position it is to hold therein must 

 first be won by fighting. For no two hens ever hve side by 

 side in a flock without having previously settled, either for 

 the time being, or for good, which is the superior and which 

 the inferior; the "pecking order" thus estabHshed decides 

 which of the birds may peck the other without fear of being 

 pecked in return. Similar pecking codes exist, according to 

 Schjelderup-Ebbe, among sparrows, wild ducks, and possibly 

 among many other kinds of animals. Pecking among cocks 

 is governed by the same rules as among hens, except that 

 the cocks exhibit greater ferocity. Such "pecking orders" 



