by Anne E. Platt

About the author: Anne E. Platt is a staff researcher at the Worldwatch Institute, an environmental policy organization in Washington, D.C.

During the last four thousand years, the part of our past that we think of as the history of civilization, human settlements have tended to cluster around land-enclosed seas, rivers, and lakes. People in these settlements have been able to supply themselves with food, security, and community to a degree that would have been far more difficult in the vast inland territories—drylands, mountains, scrub forests, deserts, and steppes—that make up the bulk of the terrestrial world.

Whether it was the ancient Aegeans on the Mediterranean, the Persians on the Caspian, or the Chinese on the Yellow Sea, civilizations rose in places where small boats...