The Red Queen: Sex and the Evolution of Human Nature

by Matt Ridley

There is a little wasp that injects its eggs into whitefly aphids, where they grow into new wasps by eating the whitefly from the inside out. Distressing but true. If one of these wasps, upon poking its tail into a whitefly, discovers that the aphid is already occupied by a young wasp, then she does something that seems remarkably intelligent: She withholds sperm from the egg she is about to lay and lays an unfertilized egg inside the wasp larva that is inside the whitefly. (It is a peculiarity of wasps and ants that unfertilized eggs develop into males, while all fertilized ones develop into females.) The “intelligent” thing that the mother wasp has done is to recognize that there is less to eat inside an already-occupied whitefly than in virgin territory. Her egg will therefore grow into a small, stunted wasp. And in her species, males are small, females large. So it was “clever” of her to “choose” to make her offspring male when she “knew” it was going to be small. But of course this is nonsense. She was not “clever”; she did not “choose” and she “knew” not what she did. She was a minuscule wasp with a handful of brain cells and absolutely no possibility of conscious thought. She was an automaton, carrying out the simple instructions of her neural program: If whitefly occupied, withhold sperm. Her program had been designed by natural selection over millions of years: Wasps that inherited a tendency to withhold sperm when they found their prey already occupied had more s...

successful offspring than those that did not.