" The story of the poles is that of the entire planet. Our present—with its polar ice—is an aberration. For most of history our planet was warm, almost tropical. If the rocks of the world are a lens, they reveal that our modern, relatively cold landscape is not the normal state of affairs for the planet. In this great cooling lies one of the major events that shaped our bodies, our world, and our ability to see "

― Neil Shubin , The Universe Within: Discovering the Common History of Rocks, Planets, and People