I wrote previously about the gender pay gap, the difference of women’s and men’s earnings, here.

That’s enough of a dark side you may think. But trust me, it gets darker.

Admittedly, the current discussion of That Pay Gap in the media is taking place largely among fairly powerful women; women who earn well enough to sustain themselves and more. The headline grabbing lawsuits on that matter usually concern women in, or just one step away from, executive leadership in profitable corporations.

What does the situation look like at the margin of empowerment, and, at the margin of poverty? To start, let’s think about a fundamental difference between men and women that is a bit uncomfortable to consider: women, also very poor women, always have a currency to pay in. There is always one thing they can offer and it’s usually worth money. Do you see where I am going? There is a huge market out there for female straight sex, and such a market does not exist for male straight sex. I am not saying this is an advantage – right now in the world it does not play out as one.

This paper by Damien de Walque and others shows that conditional cash transfers can get men and women to lead healthier sex lives and reduce their risk of contracting HIV substantially. Once the cash transfer is taken away, the behavior change persists among men but not among women.

Ouch.

Here is what happens: when the money is lacking, women need to pay with sex. Riskier sex pays better. This is not a lifestyle choice; it is a survival necessity. Men cannot do this, on the one hand; and do not need to do it on the other: they likely earn more than women anyway.

At the margin of empowerment, the gender pay gap forces women to be more available for sex.