However, the particular creatures that evoke them vary from place to place, depending on the local types of predators. Most animals learn to respond appropriately to the warning cries of other species that happen to live near them. A more elaborate form of social evolution occurs in the songs of humpback whales. Lek behavior is a kind of courtship exhibited by many species of insects, birds and mammals. A number of males gather in a defined area, each in his own piece of the space, and engage in competitive mating displays.
Females cruise through the arena, observe the displays, and choose a mate based on their evaluation.
In the case of the humpbacks, the male display appears to be a song. As a result, the following curious pattern has been observed. At any given time, all the humpbacks in a given region are singing basically the same song. Over time, the pattern evolves, until after a year or so, it is completely changed. All the males are still singing the same song, but it is a completely different song than it was before.