The caldera of the Sierra Negra Volcano on Isabela Island is one of the largest in the world, measuring seven miles across. The volcano last erupted in 2005, filling part of the caldera shown here. The Galapagos Islands formed at the meeting of two continental plates, the Nazca and South American plates. Hot spots at these plate boundaries have shifted over time, with the islands forming in a general southeast to northwest position and the oldest islands 3-4 million years old. The island of Isabela is thought to be about one million years old, with Fernandina Island, to the west, the youngest at 700,000 years old. Thus the Galapagos comprise some of the youngest islands on earth, which makes their colonization more recent. Darwin observed, “Seeing every height crowned with its crater, and the boundaries of most of the lava-streams still distinct, we are led to believe that within a period geologically recent the unbroken ocean was here spread out. Hence, both in space and time, we seem to be brought somewhat near to that great fact—that mystery of mysteries—the first appearance of new beings on this earth.” Seeing how life originates on new islands helps us understand how new species evolve over time in response to their environments.