We all know what fueled the sexual revolution: birth control and rock 'n' roll.
But what if that's not the whole story? What if America's libido was liberated not by the pill and heady doses of Jim Morrison, but by the lowly prescription drug penicillin.
Before penicillin was found to be effective against syphilis during World War II, sex brought with it the risk of syphilis, a disease that can cause blindness, dementia and paralysis.
Penicillin can wipe out syphilis with just one shot. As the antibiotic came into wide use in the 1950s, the number of syphilis cases and syphilis deaths plummeted. And that's when teen pregnancies and illegitimate births began to rise long before the invention of the birth control pill.
That's the provocative thesis of Andrew Francis, an economist at Emory University in Atlanta who studies HIV/AIDS and the cost of disease. He knew that the rate of new HIV infections spiked after antiretroviral treatments used widely after 2000 made the disease less of a death sentence.
Francis was browsing through historical trends in gonorrhea rates one day, when he saw that the rate of this non-deadly STD really started cranking up in the early 1950s. "Really?" Francis said to himself. "What was going on in the 1950s?"
Like many of us, Francis thought of the '50s as the era of Pat Boone and repressed sexuality. Being an economist, he started running the numbers to find out what was going on. His graphs show an almost perfect correlation between the end of syphilis as a deadly sexually transmitted disease, and the beginning of an era of risky sexual behavior. Down goes the syphilis death rate. Up goes the rate of gonorrhea infections, births out of wedlock, and births to teens.
Now correlation isn't causation. But by Francis's calculation, the sexual revolution was already well underway when the Food and Drug Administration approved the birth control pill in 1960, and the Supreme Court's protection of abortion rights in 1973.
You might want to take a peek at his study, which published in the January Archives of Sexual Behavior. It's a rare observational study that has graphs this intriguing. (We made the video above from data behind Figure 3.)
Francis says he knows that there was a lot more going on in the 1950s than just access to penicillin; the social and political forces that shaped the 1960s and 1970s were not solely driven by freedom from fear of disease.
But the cost of disease not just the financial costs, but the pain and suffering, the years and lives lost do shape history. And sex lives.
"Weirdly, ironically, it was penicillin that set the stage for HIV/AIDS," Francis says. "Those sexual behaviors continued to rise through the '60s and '70s, into the early '80s. People really weren't worried about life-threatening illnesses."