 What happened to Earth?
The ancient rule was sink or swim—swim in the miasma of a planet without spaceflight, or sink to utter destruction! [Transcriber's Note: This etext was produced from Worlds of If Science Fiction, July 1963. The planet chosen for our Trial was called Tintera. The last contact the Ship had had with it—and we were the ones who dropped them—was almost 150 years ago. The thought that made me unhappy was that I would have to be on a planet for a whole month. Planets make me feel wretched. A planet is all right for a Mud-eater, but not for me. We have a place in the Ship like that—the Third Level—but it's only a thousand square miles and any time it gets on your nerves you can go up a level or down a level and be back in civilization. When we reached Tintera, they started dropping us. They don't let us grow for fourteen years and then kick us out to die. Daddy says that something has to be done in a closed society to keep the population from decaying mentally and physically, and this is it. The ship lifted impersonally away from Ninc and me like a rising bird, and in just a moment it was gone. When the sun disappears, somehow you wonder in your stomach if it's really going to come back. It was spring on Tintera, but it was December in the Ship, and after we got back we had five days of Holiday to celebrate.
 Overpopulation caused a war
 People divided into small, vicious colonies  Overpopulation caused a war  People discovered more planets and chose to move  Everyone chose to live in space