What is Wal-Mart—in a strictly taxonomic sense, that is? Based on size alone, it would be easy to confuse it with a nation: In 2002, its annual revenue was equal to or exceeded that of all but 22 recognized nation-states. Or, if all its employees—1.4 million in the U.S. alone—were to gather in one place, you might think you were looking at a major city. But there is also the possibility that Wal-Mart and other planet-spanning, centi-billion-dollar enterprises are not mere aggregations of people at all. They may be independent life-forms—a species of super-organisms.