Griffin Hansbury, who was born female but underwent a sex change after graduating from college, has another well-informed view of the powers of testosterone. “The world just changes,” he said. “The most overwhelming feeling was the incredible increase in libido and change in the way I perceived women.” Before the hormone treatments, Hansbury said, an attractive woman in the street would provoke an internal narrative: “She’s attractive. I’d like to meet her.” But after the injections, no more narrative. Any attractive quality in a woman, “nice ankles or something,” was enough to “flood my mind with aggressive pornographic images, just one after another. . . . Everything I looked at, everything I touched turned to sex.” He concluded, “I felt like a monster a lot of the time. It made me understand men. It made me understand adolescent boys a lot.”

— Christopher Ryan and Cacilda Jethá, Sex at Dawn