So that in selecting a mate from a number of different competitors, it is important to select that one which is most likely to produce successful children. The first step to a solution lies in the fact that the success of an animal in the struggle for existence is not measured only by the number of offspring which it produces and rears, but also by the probable success of these offspring. Granted that while this taste and preference prevails among the females of the species, the males will grow more and more elaborate and beautiful tail feathers, the question must be answered 'Why have the females this taste? Of what use is it to the species that they should select this seemingly useless ornament?' Female mating preferences are widely recognized as being responsible for the rapid and divergent evolution of male secondary sex characteristics.
