26 Studies in Animal Behavior 



between the simple family and the highly organized 

 social state. Many insect communities consist merely 

 of an enormous family resulting from a single fe- 

 male parent; and when the community includes more 

 than this the condition is generally a secondary out- 

 growth of the domestic group. 



In the care of parents for their young we prob- 

 ably find also the first traces of altruistic instinct. 

 } ' Family life is impossible on the basis of purely egois- 

 ' . tic behavior. Some altruism, however weak and 

 limited in its scope, is the essential condition of the 

 family group. In low forms it is limited to the care 

 for offspring; later it may include other members of 

 the species beyond the limits of the family; but it 

 is a long time before it extends its blessings at all 

 widely. Most creatures care not a fig for the wel- 

 fare of any but their own immediate kin ; and where 

 we find any consideration bestowed upon alien forms, 

 as in the fostering of aphids by ants, it is done for 

 the sake of something to be gained in return. Ani- 

 mals in general livd under conditions in which they 

 cannot afford disinterested benevolence. While the 

 long hard struggle for existence may have bred 

 tender feelings and unselfish impulses it has pro- 

 duced them for the same ultimate purpose that is 

 subserved by sharp claws and good teeth, — the sur- 

 vival and perpetuation of the species. Parental care 

 is one of Nature's devices for race survival. But 

 very few of the devices which Nature has hit upon 

 have influenced so profoundly the course of evolu- 



