Kin recognition in vertebrates: what do we really know about adaptive value?

The ability of an animal to discriminate between kin and non-kin (kin recognition) has been the subject of numerous recent investigations. Grafen ( Anim. Behav. , 1990, 39 , 42–54) recently reported that the evidence in support of kin recognition is weak and the data illustrating a preference for kin to associate in the laboratory may be more consistently explained as species recognition. It is suggested here, however, that in many cases it may be impossible to distinguish between species recognition and kin recognition, but in some cases, kin recognition seems apparent. It is also emphasized that very little is known about the adaptive value of kin recognition.