MEGAN MCARDLE: No Antibiotics, No Sexual Revolution.

Most of us, if we think about it at all, probably attribute the rise in premarital sex to The Pill, among other factors. But before the birth control pill, there was another invention that was just as necessary: antibiotics.

The sexually transmitted diseases of yesteryear were pretty nasty. If you’re interested, you can Google up images of tertiary syphilis, but I don’t recommend it unless you’ve got a strong stomach. The initial symptoms of various common STDs were also unpleasant, and in women, could severely impair your fertility. You could use condoms, of course, but then, you could also use condoms to prevent pregnancy.

Then suddenly STDs weren’t so risky. You might have to make an embarrassing visit to the doctor and get a shot, but that’s nothing compared with horrible treatments using arsenic or mercury that were mostly ineffective. It’s no coincidence that the sexual revolution seemed to come to an abrupt halt when AIDS entered the scene. And as I understand it, AIDS is relatively hard to get compared with other STDs.

Without antibiotics, any chance sexual encounter could lead to a permanent disease that, among other things, would probably make it hard to find a long-term relationship partner. In that world, we’d probably have a lot fewer chance sexual encounters.

So thank antibiotics for your open heart surgery — but while you’re at it, thank them for your sexual freedom, too.

Well, and unless things improve, you can wave goodbye to all of that. . . .