For most of the Earth's history, life consisted of the simplest organisms; but then something happened that would give rise to staggering diversity, and, ultimately, life as complex as that which we see today. Scientists are still struggling to figure out just what that was.
See the extraordinary wildlife and people of the Andes. Pumas hunt guanaco, shape-shifting frogs hide in remote cloud forests and the descendants of Inca build bridges of grass. The world’s driest desert, huge salt lakes and spectacular peaks are all found in the world’s longest mountain range.