The Selfish Gene

by Richard Dawkins

What is harder to understand is the behaviour of foster parents later in the season, towards young cuckoos that are almost fledged. The cuckoo is usually much larger, in some cases grotesquely larger, than its ‘parent’. I am looking at a photograph of an adult dunnock, so small in comparison to its monstrous foster child that it has to perch on its back in order to feed it. Here we feel less sympathy for the host. We marvel at its stupidity, its gullibility. Surely any fool should be able to see that there is something wrong with a child like that. I think that cuckoo nestlings must be doing rather more than just ‘fooling’ their hosts, more than just pretending to be something that they aren’t. They seem to act on the host’s nervous system in rather the same way as an addictive drug. This is not so hard to sympathize with, even for those with no experience of addictive drugs. A man can be aroused, even to erection, by a printed photograph of a woman’s body. He is not ‘fooled’ into thinking that the pattern of printing ink really is a woman. He knows that he is only looking at ink on paper, yet his nervous system responds to it in the same kind of way as it might respond to a real woman. We may find the attractions of a particular member of the opposite sex irresistible, even though the better judgment of our better self tells us that a liaison with that person is not in anyone’s long-term interests. The same can be true of the irresistible attractions of unhealthy food. Th...