 What does the narrator say was the reason for Earth’s destruction?
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. 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. 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.
 Over population
 Losels  Over population  Lack of horses  Crime