Manfred Milinski of the University of Berne, who gave the conference's opening talk, showed a few years ago that female sticklebacks not only identify a breeding male by his belly, but also judge him by just how red that belly is.

ECONOMIST: Birds do it, bees do it | The

Tinbergen started the fashion for using sticklebacks to study mating strategies by showing that the red belly which a male develops when he is ready to breed is a badge that promotes aggression in fellow males, while signalling to females that he is available to court them.

ECONOMIST: Birds do it, bees do it | The