Two of the twentieth century's worst technological innovations were leaded gasoline and chlorofluorocarbons. Both were introduced by the same person, engineer Thomas Midgley.

In the 1920s, most took it for granted that Western civilization and culture was the pinnacle of human accomplishment. A 23-year-old graduate student set out to prove that this was not the case, and that even the West had something to learn from other cultures.

Charles Darwin himself noted that the development of civilization had "stopped" evolution by natural selection within our own human species. This led others to speculate on whether society could purposefully direct human evolution.

The state of Tennessee had made it a criminal offense to teach evolution in the public schools. The trial of John Scopes became the most famous court case in America of the period.