Since the first cautious steps in the Great Rift Valley, humans have adapted to the challenges of Africa. Today, it is divided into more nations than any other continent. But as this satellite-derived map shows, landscapes that ignore national boundaries form a mosaic of ecosystems that blend subtly into one another—from the temperate Mediterranean to forest, marsh, and savanna, to desert and scattered farmland—each with its own rules for life. Published in September 2005 as one half of a two-map set with "Africa: The Human Footprint."