Do animals really recognize kin?
Species recognition and group member recognition systems produce an ability to discriminate conspecifics by genetic similarity on first encounter when kin recognition is absent. Experimental evidence of such discrimination is therefore insufficient evidence for kin recognition. The evolution of a true kin recognition system depends on three kinds of loci: matching, detection and using. Matching loci, which affect the traits used to detect kin, will have a higher genetic similarity between interactants than their common ancestry alone suggests. Selection has been erroneously thought to cause individuals to behave according to the higher relatedness implied by this extra similarity. The detection loci and using loci are not expected to be closely linked to the matching loci, implying that individuals will behave according to the relatedness based on their common ancestry. Polymorphism at the matching loci is essential for effective discrimination of kin, and is sustained by the evolution of the kin recognition system in those cases where it is advantageous to interact with kin. © 1990 The Association for the Study of Animal Behaviour.