Is More Sex Safer Sex?

Back in 1996, when HIV was considered the scariest thing around, Steve Landsburg arguably kicked off the Economics-of-Everyday-Life fad with his inaugural Slate column titled "More Sex Is Safer Sex."

(I'm kind of amazed that I have a link for you that's from over a decade ago. Is the information superhighway really that old?)

The argument in the controversial piece, which he later adopted for his 2007 book of the same name, goes like this:

If people who abstained from casual sex because they were afraid of catching STDs changed their minds and started to unzip a little more, it would actually DECREASE the chance of STD transmission in the entire population.

The reasoning is fairly straight-forward.

If 10 percent of the sexually active population has HIV, then on any given night that you walk into a bar or party looking to hook up, you have a 10 percent chance of having sex with someone who has HIV. But if the abstainers joined the crowd, and importantly, practiced safe sex, that would decrease the chance that you end up in bed with someone with HIV.

More risk taking by the abstainers reduces the risks for the rest of us.

This argument was based on the work of Harvard economist Michael Kremer in the 1990's that was heavy on theory but light on real-world data. (Read a recent IMF profile of Kremer here.)

Now, two studies looking at a society's level of acceptance of homosexuality provide some evidence that Kremer was onto something.

In the first, economists from Emory University, Andrew M. Francis and Hugo M. Mialon look at the HIV infection rates -- which had a disproportionate impact on the gay male population in the U.S. -- and tolerance towards homosexuality in the United States. They find that a drop in HIV rates during the early 1990's coincided with a two-fold rise in the acceptance of gays in the U.S. (as measured by the long-running General Social Survey).

But was there a link between the two?

Francis and Mialon unearth evidence suggesting there was. For a proxy of safe and risky homosexual activity, they turned to the Damron Men's Travel Guide which keeps an annually updated list of "formal establishments" and "cruisy areas" all over the United States. Francis and Mialon found that the number of cruisy areas -- places like parks, beaches, and other public grouds where unsafe sex was more likely to be practiced -- was positively linked to HIV rates while the number of formal establishment -- businesses like bars and nightclubs -- was negatively linked. This makes sense in that in a society that doesn't look favorably upon homosexuality, gays will need to find partners in secret or out-of-the-way place more conducive to high-risk sex.

Francis and Mialon's results imply that wider acceptance of homosexuals decreased HIV rates through two different means:

- With less stigma attached to homosexuality, more safe places for meeting other gay men opened up. With these new options, men who had previously frequented cruisy spots switched over to the safer places and cut back their risky behavior. In this case, the amount of sex mostly stays the same, it's just moved from one part of the world to another.

- Low-risk gay men, those who because of societal pressures only had female partners or kept their matings to a minimum, were more likely to enter the sexually active gay male population. In this case, more sex is being had by people who are likely to practice safe sex, and as Landsburg and Kremer postulated, and help push down HIV rates.

Unfortunately Francis and Mialon don't have the data to piece apart which effect is the main driver.

In the second study soon to be published in Economic Journal, Thomas Dee of Swarthmore College found that syphilis rates dropped by 24 percent after various European countries legalized same-sex partnerships. (The effects on HIV were inconclusive.)

While neither study proves Landsburg and Kremer's logic, they do give it some support. And perhaps more importantly, they show that greater acceptance of homosexuals diminishes the need for riskier sex.