If, in the Greylag Goose and in man, highly complex norms of behaviour, such as falling in love, strife for ranking order, jealousy, grieving, etc., are not only similar but down to the most absurd details the same, we can be sure that every one of these instincts has a very special survival value, in each case almost or quite the same in the Greylag and in man. Only in this way can the conformity of behaviour have developed.
The more complex and differentiated two analogously constructed and similarly functioning organs are, the more right we have to group them in the same functional conception and to call them by the same name, no matter how different their phylogenetic origin may be. When Cephalopods, like the Octopus, Squid, and Cuttlefish, on one hand, and vertebrates on the other have invented, independently of one another, eyes built from the same principles as the lens camera, and when in both cases these organs have similar constructional units such as lens, iris, vitreous humor and retina, no reasonable person will object to calling both the organ of Cephalopods and that of the vertebrate an eye—without any quotation marks. We are equally justified in omitting the quotation marks when speaking of the social behaviour patterns of higher animals which are analogous of those of man.
All that I have said in this chapter should be a warning to the spiritual pride of many people. In an animal not even belonging to the favoured class of mammals we find a behaviour mechanism that keeps certain individuals together for life, and this behaviour pattern has become the strongest motive governing all action; it can overcome all “animal” drives, such as hunger, sexuality, aggression, and fear, and it determines social order in its species-characteristic form. In all these points this bond is analogous with those human functions that go hand in hand with love and friendship in their purest and noblest form.