In The Descent of Man, and Selection in Relation to Sex (1871), Darwin suggested natural selection can occur by individuals out-producing others in a population, through enhanced ability to secure a mate.
Darwin used the ornate peacock plumage and bird songs to exemplify this concept.
Peacocks are best known for flaunting their brightly coloured and sizable tails. Yet the tail is cumbersome and expends energy.
In addition, its extravagance makes the peacock conspicuous to predators and less able to escape them, reducing its survival prospects. Why then has the tail not been bred out of existence?Read more at: