19. Peacocks, with their fabulous tails, live wild in the jungle. There, a tail is a detriment — it slows the birds in flight, and presents an excellent handle for a predator to grab hold of. Nevertheless, males continue to grow them because peahens love bling, and the more, the better.

a. Explain the value of a long tail as a signal, focusing on the general principle that signals must be costly to a strong bird, but even more costly to a weak bird.

b. Peahens would receive the same information if all peacocks cut their tails in half. In light of this truth, explain why the signal is socially costly.

c. Suppose all male peacocks agreed to cut their tails in half. Explain why such an agreement is unlikely to last, and why the disintegration of the agreement makes all peacocks worse off.