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1. A new male trait arises, one that increases the mating success of the males. Females are attracted to the trait. Females that mate with males that have the new trait have offspring that carry both the genes for the trait and the genes for the preference for that trait.

2. The fitness of the males with this trait rises. The fitness of the females responding to this trait also rises. Hence, males with this trait become more numerous in the population, and females responding to the trait also become more numerous.

3. Some males evolve a more extreme version of the trait, which is even more attractive to females.

5. The cycle continues. The trait becomes ever more extreme (until natural selection counters the evolution of the trait) and the preference also becomes more extreme over time.

The key to understanding the cycle is that male fitness and female fitness are linked. Hence, selection on the trait and the preference for the trait causes a positive feedback loop