The opening session talked less of goslings and rooks than of an animal that was one of Tinbergen's favourite toys the three-spined stickleback.

ECONOMIST: Birds do it, bees do it | The

Even if she does not go to the hideous expense of nurturing a single offspring in her womb for nine months but, like a stickleback, simply lays her eggs in a nest prepared by a male, she still has to produce those eggs.

ECONOMIST: Birds do it, bees do it | The