I was watching (as is my wont) another nature program yesterday, about penguins. Among many marvelous things I was struck by one scene in particular: after showing the remarkable parental devotion of the parents, the camera caught them feeding their chick for the last time and then waddling off to leave it to fend for itself, quite contrary to its wishes. You wondered: why so much love and then such sudden abandonment? But then you remember: those selfish genes are primarily concerned to maximize their numbers and the best way to do that is to get the parents to produce another chick, not spend more time on this one. You could almost hear the genes speaking: “That’s enough with that one, now get to work to produce another!” Evidently there are penguin genes for strong parental love but also penguin genes for turning this love off. Could anything similar be true for humans?