Troops of penguins, if they have been out of the water for a time, are very wary about diving into the sea; after all, there are often unfriendly creatures down there. Instead, these gregarious birds solemnly cluster around the edge of the ice, studying the water, leaning over the edge, backing away, bowing, and politely making room for anyone else who might want to step to the brink and maybe even test the water. Soon, building up excitement, the whole troop begins milling and shifting at the water's edge. As happens in crowds, even the politest of crowds, near a brink, someone sooner or later is jostled over the side. Once this happens, the who troop stands still and watches. If their "volunteer" is attacked or gobbled up, his friends and relatives find some way to entertain themselves on shore for a while longer. If, on the other hand, the penguin goes through a series of aquabatics with no ill result, the whole gang of his fellows stage a swim-in. - Bill Zeckendorf