Set hundreds of years in the future the 1951 C. M. Kornbluth short story “The Marching Morons” tells the story of an Earth overrun by the unintelligent. Just as eugenicist’s predicted, this future is the result of overbreeding by the “unfit” and the average IQ is just 45. The ever-shrinking elites are too small in number to overcome the enormity of the problem until John Barlow arrives from the past with a eugenics solution: the morons are convinced to migrate to Venus only to be euthanized in their spaceships!
The scientific eugenics movement may have declined in the 1930s and lost popular support following the revelations of Nazi atrocities during WWII, but eugenic ideas have continued to be reused in popular culture consistently. Check out the whole story here.