230 SOCIAL BEHAVIOUR 
exception in the animal world, but is the rule, the law of 
nature.” Many will contend, on the other hand, that life in 
societies with anything like division of labour, or with mutual 
aid (and this seldom carried far), is, taking the animal kingdom 
as a whole, of comparatively rare occurrence, though none the 
less noteworthy where it exists. And, in any case, it seems 
somewhat extravagant to say that sociability is the chief factor 
in evolution. No doubt it might be plausibly urged that 
human society is, from man’s point of view, the highest 
product of evolution ; that in attaining to this end sociability 
has been the leading factor ; and that obviously the leading 
factor in the evolution of the highest product may properly 
be called the chief factor in evolution. But Prince Kropotkine 
apparently means that sociability is the chief factor, not only 
in this evolution, but in all organic, or, at least, all animal 
evolution. In this he will receive the support of but few 
zoologists. By some extravagance of statement he has 
weakened his own case, which is otherwise not lacking in 
points of weakness. The legitimate inferences from animal 
behaviour are, that co-operation is in some cases a factor in 
the evolution of a successful species, that in human progress 
it has been an important factor giving strength to a creature 
weak in tooth and claw, and that this factor has co-existed, 
and still coexists, with that of competition, in the absence of 
which the race would be dragged down to lower levels of 
efficiency by the incubus of weaklings. 
To Professor Alfred Espinas * we owe the best and fullest 
discussion of the social life of animals, and to his work the 
reader may be referred for a careful and, for the most part, 
unstrained and unbiassed consideration of the phenomena. 
In common with others who have devoted serious attention 
to the subject, he sees in the family the starting-point of the 
higher and more comprehensive social group, or “ peuplade.” 
Prince Kropotkine seems, indeed, to combat this view ; but 
the divergence of opinion is more apparent than real. He 
* “Des Sociétés Animales: Htude de Psychologie Comparée” (Paris, 
1877). 
