Did penicillin change our view of sex?

Penicillin is arguably one of the greatest achievements of modern times. Discovering that infections were not just something we must live with and potentially die from, but something that could be actively fought, revolutionised the field of medicine. Since its discovery, countless lives have been saved in the operating theatre, the maternity ward and on the battlefield. Penicillin has the power to sustain life, but we haven’t stopped to think what such a powerful force is having on the lives that are being saved. Specifically, did penicillin pave the way for the sexual revolution of the 1960’s and the modern view of sex?

It took 13 years from the discovery of penicillin by Alexander Fleming in a sample of mould in 1928 before the first clinical trials took place showing penicillin was an effective cure for syphilis. Prior to this, syphilis had a number of nasty symptoms making sex quite a dangerous option for many people. Syphilis usually starts with open sores and ulcers, with fevers, rashes, hair loss and headaches developing later. In severe cases, it can affect the nervous system and could cause deafness, seizures and personality changes. Untreated, its death rate has been reported as high as 58%. Some incredibly famous and influential people have died from syphillis over the years, including Christopher Columbus, Franz Shubert and Al Capone.Before the introduction of penicillin, treatments for syphilis were just as likely to kill you as the disease, the most common one being mercury.

The spirochete bacterium Treponema pallidum causes syphilis

With some very disfiguring symptoms, and a high chance of death, it seems likely that before penicillin was widespread, people would be cautious about how often they had sex, and who they had it with. After pencillin, the opposite should be true. This is the hypothesis given by Andrew Francis, a professor of economics at Emory University in Atlanta.

Obviously human sexuality is a complicated beast. After all, there are dozens of reasons why any of us would choose to sleep with someone or not. Risk of STDs are definitely a good reason, but another is the risk of pregnancy. Indeed, the introduction of widely available contraception – notably the contraceptive pill – in the 1960s is widely seen as the reason for the start of free love and the ongoing period of sexual liberation.

Francis believes, though, that this hypothesis doesn’t add up. Firstly, the dates don’t match. Riskier sex – ie non marital sex, more sex partners, sex at a younger age –  in the US started becoming more common in the late 50s and 60s, but it was only in 1972 when the U.S. Supreme Court allowed all unmarried couples access to the pill. And, while the pill may lower the chance of pregnancy, there is little evidence to show it correlates with an increase in risky sexual behaviours.

What does seem to correlate is an increase in non-marital sex with the collapse of syphillis. Not only did the incidence of the disease drop in the 1950s and 60s after a huge national health campaign using antibiotics, but also the death rate. Therefore, the risk of performing risky sex was lower. And, as economists love to point out all the time, if you lower the risk of a penalty for performing a certain act, while keeping the reward constant, the frequency of that act will increase. It’s only rational.

To measure the perceived risk of syphillis, Francis turned to three pieces of data available to him at the time that would be related to the frequency of risky sex – the gonorrhea rate, the illegitimate birth ratio, and share of births by teenagers. The first was availble from 1941, while the last two have been recorded by US states since 1937. Using a regression analysis, he showed the all three rose steadily all the way to 1975.

What is incredibly interesting is a parellel this tale has with that of AIDS in the modern era. Before the discovery of HIV and AIDS, unprotected sex, especially in the homosexual community, was common. But as its devestating effects became more well known, such risky behaviour came to be seen as nar-suicidal. Perhaps with the introduction of effective HIV vaccines and retroviral therapies in the near future, a new sexual revolution will emerge. Time will tell.



Charlie is a science writer from London. He tweets @UnpopSci.

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