In “The Other Olympians: Fascism, Queerness, and the Making of Modern Sports,” the journalist Michael Waters tells the story of Zdeněk Koubek, one of the most famous sprinters in European women’s sports. Koubek shocked the sporting world in 1935 by announcing that he was transitioning, and now living as a man. The initial press coverage of Koubek and another prominent track star who transitioned, Mark Weston, was largely positive, but Waters tells the New Yorker sports columnist Louisa Thomas that eventually a backlash led to the 1936 Berlin Olympics instituting a sex-testing policy for women athletes. Any female athlete’s sex could be challenged, and cisgender women who didn’t conform to historical gender standards were targeted as a result. These policies slowly evolved to include chromosome testing and, later, the hormone testing that we see today. “And so as we talk about sex testing today,” Waters says, “we often are forgetting where these policies come from in the first place.”