The good genes hypothesis holds that males develop impressive ornaments to show off:

1. Costly ornaments need an explanation in fitness terms. 2. The good genes hypothesis states that males develop these impressive ornaments. 3. They do so to show off their efficient metabolism or their ability to fight disease. 4. The handicap principle offers a parallel explanation. 5. In both, the trait is an honest signal of the males' quality. _Source: OpenStax Biology 2e (CC BY 4.0), Ch 19 'The Evolution of Populations', sections 19.1-19.3_