question:  What happened to Earth?
context: 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. 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. 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. It was narrow and made of sand spread over a hard base. One of the smartest moves in history was to include horses when they dropped the colonies. I say "they" because, while we did the actual dropping, the idea originated with the whole evac plan back on Earth. Considering how short a time it was in which the colonies were established, there was not time to set up industry, so they had to have draft animals. One of the eight, as well as the two that were being built then, went up with everything else in the Solar System in 2041. I don't know how many of those planets had animals that could have been substituted but, even if they had, they would have had to be domesticated from scratch.
output:  Overpopulation caused a war
options:  People divided into small, vicious colonies  Overpopulation caused a war  People discovered more planets and chose to move  Everyone chose to live in space