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Sorry, Hippies: Sexual Liberation Began in the 1950s Thanks to Penicillin

A new study suggests that curing syphilis, not popularizing the pill, was what first got things cookin'.
Repression and housewifery weren't the only things going on in the 1950s. Image via Stirred, Straight Up, With a Twist

As anyone who’s read John Cheever knows, 1950s America, despite its staid, sanitized pretensions, was often simmering behind closed doors. But don’t take Cheever’s word for it. A new study suggests that, despite Baby Boomer claims to have invented sexual liberation, it was the post-war generation that really got things cooking.

The reason? According to Emory University economist, Andrew Francis, it wasn’t just the emergence of the pill in 1960 that liberated sex, as popular narrative has it. The initial rise in “non-traditional” sexual relations, he argues in a new study, published in the Archives of Sexual Behavior, accompanied the collapse of syphilis by the mid-1950s.


Syphilis in its heyday was fairly terrifying. It was, first of all, deadly—“the AIDS of the late 1930s and early 1940s,” as Francis called it in an interview for an article about the study, released by Emory. Although the penicillin used to treat syphilis was discovered in 1928, it wasn’t put into widespread clinical use until 1941. Al Capone and Henri de Toulouse-Lautrec were just a few famous people who died from it before a cure was found.

Because it wasn’t getting cured, it was also running rampant. In 1939, it reached the peak of its deadliness, killing 20,000 people. But during World War II, doctors treating soldiers overseas (who, it’s no secret, kept Europe’s brothels extra busy) figured out penicillin was an effective cure. Between 1947 and 1957, the incidence rate of syphilis fell by 95 percent and its death rate fell by 75 percent. It became, for the most part, a non-issue.

Francis examined public data on three factors in attempts to measure the rise of so-called “non-traditional” sex—i.e., sex out of wedlock. Given the generally private nature of unwedded sex, particularly in the 1950s, no scientist could pretend to get a true sense of its prevalence. But Francis was able to three factors over time that, measured comparatively across time, should provide decent indicators of change: the illegitimate birth ratio, the share of U.S. births by teens, and the incidence of gonorrhea.


“As soon as syphilis bottoms out, in the mid- to late-1950s,” Francis said, “you start to see dramatic increases in all three measures of risky sexual behavior.”

A WWII-era public health poster. Image via Vector Control

The logic underpinning Francis’s findings is really just basic economics. In one sense, it’s simple supply-side theory. If non-deadly sex is the product, and that product suddenly becomes abundant, some people who previously abstained will start taking part.

And on a case-by-case basis, every sexual encounter usually follows a (often hasty, often drunken) cost-benefit analysis. “Is what I am about to receive from sex—from pleasure to power to relationship-building—worth the potential risks?” we ask, including disease, pregnancy, loss of power, and, in some cases, relationship-sabotage? A greatly reduced, non-deadly syphilis is a mostly negligible syphilis in that equation, and was bound to make casual sex more attractive.

“People don’t generally think of sexual behavior in economic terms,” Francis said. “But it’s important to do so because sexual behavior, just like other behaviors, responds to incentives.”

Such economic calculus seems fairly rational compared to some of the choices we make about sex. But as economist, Tim Harford, argues out in his 2008 book, The Logic of Life, even some of our mostly seemingly irrational choices about sex are undergirded by similar economic logic.

A study in Morelia, Mexico, for example, found that despite intense public health efforts, many prostitutes weren’t insisting their Johns use condoms. “It’s tempting to argue that the prostitutes do not understand the risks,” Harford writes, but “That’s patronizing.” In truth, condoms are a “bargaining chip,” he says. Only one in 800 Mexicans and one in 300 Mexican prostitutes carries HIV, and a prostitute’s chance of contracting HIV is less than 2 percent when her john is a carrier. On the other hand, prostitutes command about 25 percent more money when they agree to go unwrapped.

“Far from being rash or stupid, the choices that young Mexcian prostitutes are making are astonishingly similar to those made by workers in rich countries who accept dangerous jobs in exchange for higher salaries—construction workers, lumberjacks, soldiers.” Harford writes.

As a case study, the new syphilis research is instructive for how we’re living today, too. As risk mitigates, people adapt. “Some studies have indicated that the development of highly active antiretroviral therapy for treating HIV may have caused some men who have sex with men to be less concerned about contracting and transmitting HIV,” Francis notes, “and more likely to engage in risky sexual behaviors.”