It might be thought that courtship only occurs in the kind of animals which have fairly complex brains, such as mammals and birds. This is not the case. Male "Drosophila" flies have to do a mating dance in front of the female before she will allow them to mate. If the dance is not "correct" for that species, she refuses the male. It was discovered over fifty years ago that, if the male carries a mutation which disrupts the dance, he cannot achieve mating: the females reject him. This behaviour is clearly advantageous to the female, whose genes have a better chance of contributing to the next generation if her partner is biologically fit. "Drosophila" are by no means the only insects which have mating rituals.