From a purely evolutionary standpoint, pet keeping is an anomalous activity. It is easy to explain, for example, why people keep chickens, pigs, or sheep: these animals are worth at least their own weight in eggs, meat, hide, or fiber. But what could possibly be the adaptive value of keeping Siamese cats or miniature schnauzers? A common response to that has evolutionary puzzle, and one that keeps being regurgitated in the literature, is the idea that pets are simply social parasites who have perfected the art of releasing and exploiting our innate parental instincts-called "cute response". Parallels are sometimes drawn with the phenomenon of brood parasitism in birds, in which the parasite's nestling seems to exaggerate many of the care-soliciting aspects of the host's, thus insuring that it is fed assiduously to the detriment of its foster parents and siblings. The superficially infantile appearance of some lapdogs lends support to this idea, but it should be emphasized that a key difference between people and songbirds is that the latter are presumably unaware that they are feeding and caring for a non conspecific intruder. People may indeed find puppies or pug dogs cute, but they are certainly never in any doubt concerning their true provenance.