12 dams that changed the world

Dams illustrate the brilliance and arrogance of human ingenuity. They generate one-sixth of the world's electricity and irrigate one-seventh of our food crops. They have flooded land areas the size of California, displaced a population the size of Germany's, and turned freshwater into the ecosystem most threatened by species extinction. Below are 12 of the 57,000 large dams that have changed the face of our planet.