384 ELEMENTS OF BIOLOGY 



intelligence; in both it represents a response to the necessities im- 

 posed by the food chain relation among living forms. 



The exercise of intelligence, then, in the cultivation and handling 

 of foods is a matter of ingenuity of method rather than of original- 

 ity of principle. Associated with and as a consequence of intelli- 

 gence is a certain restlessness that distinguishes human behavior in 

 general. Other animals have solved their problems, or at least do 

 not improve their solutions; the primitive method employed by the 

 cat in catching mice continues to characterize cats and has never 

 given rise to the development of a mouse trap. On the other hand, 

 no human problem is ever permanently solved or static. 



Social Life within the Species. The grouping together of 

 animals of the same species represents, in the main, functional 

 adaptations and serves various purposes. Such communities range 

 from the seasonal and temporary aggregation of birds into flocks to 

 include highly organized social communities. True social groups 

 exhibiting cooperative effort and differences in duties do not occur 

 among animals lower than the insects. Nevertheless, temporary ag- 

 gregations of some of the simple Metazoa exhibit some interesting 

 characteristics. Recent studies have shown that small aquatic ani- 

 mals are better able to resist poisons and temperature changes when 

 in groups than when exposed singly. Moreover, individuals in such 

 bunchings appear to conserve energy, for their rate of respiration is 

 lower than when they are distributed singly. The reasons for these 

 differences between the physiological characteristics of an individual 

 when a member of a close group and when isolated are not yet 

 clear. It is certain, however, that this tendency to form bunches 

 characteristic of small crustaceans, worms, and other forms consti- 

 tutes a protective action of considerable importance in the mainte- 

 nance of life under unfavorable conditions. 



Because of their intricate nature and the contrast with human 

 society, the social lives of insects have always been of interest. Social 

 organization among certain insects, particularly the bees and ants, 



