SOCIETAL EVOLUTION 1 45 



Some authors have endeavored to derive the societies 

 from the associations, but it is difficult to find any cogent 

 proof of their contentions. The societies really represent 

 very different emergent levels from the associations and 

 have arisen in a different way, though, of course, ancient 

 aggregative or associative proclivities may have been 

 retained by many species and may serve to reinforce their 

 specifically social behavior. The members of societies, as 

 distinguished from the associations, are primarily concerned 

 with their adaptations to one another, i.e. with neutralizing 

 their individual antagonisms, and with their mutual adjust- 

 ment and cooperation. The mass of stimuli which elicit 

 these adaptive responses may be called the social medium. 

 It constitutes a very complex and unstable environment 

 for the individuals, and successful and enduring adjustment 

 to it presupposes a high sensitivity and considerable behav- 

 ioristic plasticity on the part of the consociated organisms, 

 and this in turn presupposes a highly organized neuro- 

 muscular apparatus. It is clear therefore that societies can 

 be constituted only by species in which the sense-organs, 

 brain and muscular system have attained a high degree of 

 specialization, and not by animals that have never succeed- 

 ed in transcending the merely tropistic and reflex level. 

 Social life demands at least a rudimentary memory and 

 intelligence, if we understand by the latter the ability to 

 respond adaptively to new situations on the basis of pre- 

 vious experience, or in other words, some ability to learn. 

 It is obvious, moreover, that to such organisms social life 

 furnishes the only adequate opportunity for much further 

 perfecting of the intelligent activities. 



Though a rather highly developed neuromuscular system 

 is a sine qua non of social life, it is far from true that all ani- 

 mals thus equipped must become social. Tigers, hawks, 

 spiders and tiger-beetles are richly endowed organisms, 

 but they do not live in societies. Moreover, when we study 

 the positions of social species in the animal hierarchy we 

 find that they are confined to certain sporadic groups of 

 species and that they often differ externally in no respect 

 from the most closely related, highly specialized, non- 

 social forms. A worker honey-bee or hornet is quite unable 



