Heard an incredible statement yesterday:
Based on research by Michael Kremer (almost took a class with him - went to 3 lectures and took a different one, but not cuzve Kremer, who was awesome), if sexual conservatives (in Britain, people with under 2.25 partners per year) had more sex (up to 2.25 partners per year), the spread of AIDS would slow dramatically.
The argument is illustrated by landsburg (an economist) in the following manner:
If Judith is going to have sex with Michael, you'd prefer that Michael be sexually conservative.
Split it into two cases - Judith does not have HIV and Judith does have HIV.
If Judith has HIV, you'd rather she risk transmitting it to someone who doesn't have sex with many people. (This neglects all notion of justice and desert based on behavior - the only normative thing you care about is to retard the spread of HIV). This way, the virus won't spread much more quickly as a result of this encounter.
If Judith doesn't have HIV, you'd rather she be "protected" from promiscuous men - in a sense, you shield her from HIV by keeping her with a non-promiscuous partner.
This is a vast oversimplification, of course - nobody has the guarantee of going home with somebody, so rejection by a sexually conservative person doesn't imply the other party is going home with someone else. But it's an interesting thought puzzle, if nothing else.
Another way of thinking about it (also just as a thought piece) is if most women prefer monogamy, but most men prefer 2 partners, there will be a small number of women having a LOT of sex (as prostitutes or simply very, very promiscuous women) with men, because there aren't enough women to satisfy sexual demand by women. These women are highly likely to get communicable diseases and pass them on to a lot of people. If everyone preferred 2 partners, instead, the transmission would still happen, but it wouldn't happen as quickly - more people would be more links in the chain away from an HIV positive person.
Do I have any intention of listening to Kremer? Absolutely not. But it's kinda cool nonetheless.