Canopy of the tropical rain forest. Because orangs, the largest tree-dwelling animals in the world, are such accomplished brachiators. Using that arm-over arm swing, they spend their days 20 feet high in the rain forest, hanging and eating. Falling could be fatal, so they've evolved in such a way that they won't.
Orangs have extreme upper body strength, exaggerated hands and feet, and viselike fingers.
Note how their thumbs grip the thick cables and vines. The latest innovations at zoos are as wild as the animals themselves. Just ask any zoogoer who has walked forty-five feet beneath a swinging orangutan. There's more to today's zoos than lions, tigers, and bears.