The so-called "sexual revolution," which began in the 1960s, is well-known as a time in which many people's views about sex became more relaxed and some people became more promiscuous. While many credit the introduction of the birth control pill with starting the modern sexual era, an economist from Emory University says the introduction of a very different pill may have been the turning point.
Andrew Francis analyzed data from the 1930s through the 1970s from various state and federal health agencies. Specifically, he looked at the illegitimate birth rate, teen births and cases of the sexually transmitted disease gonorrhea. These factors are believed to be effected by risky sexual behaviors.
He argues that the sexual revolution actually started a decade earlier than most people think - in the 1950s. Additionally, he says the introduction of penicillin is the reason behind it because it was widely available and was effective in treating syphilis.
"It was the AIDS of the late 1930s and early 1940s," Francis said. "Fear of catching syphilis and dying of it loomed large."
It was such a threat, that the STD killed 20,000 people in 1939. However, after penicillin was introduced, infection rates were dramatically reduced. Between 1947 and 1957, the syphilis death rate fell by 75 percent and the syphilis incidence rate fell by 95 percent.
"As soon as syphilis bottoms out, in the mid- to late-1950s, you start to see dramatic increases in all three measures of risky sexual behavior," Francis said.
His research, which was published in the Archives of Sexual Behavior, argues that widespread availability of the antibiotic allowed people to engage in sexual relations without worrying about one main deterrent - a painful, debilitating and deadly STD.
"People don't generally think of sexual behavior in economic terms, but it's important to do so because sexual behavior, just like other behaviors, responds to incentives," Francis said.