I don't imagine that mathematicians get invited to the same parties as sex researchers very often. Human sexuality professors, the rockstars of the behavioral sciences department, walk into their classes and stare out at a sea of horny freshmen; your average number theory seminar is basically full of guys who couldn't hack it in computer science.

So I imagine it was rather satisfying this week when the mathematicians got to publicly tell the sex researchers they're full of shit.

For years, researchers have been telling us something that doesn't really surprise anyone: men report a significantly higher number of sexual partners than women. A recent study by the federal government put the number at seven for men and four for women, while the Brits (who knew?) reported 12.7 and 6.5, respectively.

What sex researchers would know, if they spent more time studying statistics and less cataloging items found in body cavities, is that those numbers are frickin' impossible. Since (straight) men can only have sex with women, the averages have to be the same on both sides; every time two people sleep together, a number gets added to both sides of the equation. Or, if you want to get all mathematician:

By way of dramatization, we change the context slightly and will prove what will be called the High School Prom Theorem. We suppose that on the day after the prom, each girl is asked to give the number of boys she danced with. These numbers are then added up giving a number G. The same information is then obtained from the boys, giving a number B.

Theorem: G=B

Proof: Both G and B are equal to C, the number of couples who danced together at the prom. Q.E.D.

This kind of explanation, of course, is why mathematicians don't get invited to the good parties.

Since men sleeping around more than women dovetails so nicely with our preconceived notions, it's easy to hear numbers like those and just nod. I know I have. But I like what the previous acceptance of those numbers says about our ideas of female, rather than male, promiscuity. Because even for the mathematically illiterate, the numbers sound a little hokey, and require some pretty stupid mental contortions to make them work out. For me, it goes something like:

"Well, sure, most women only sleep with like four guys. But somewhere out there there are these total sluts, these super-skanks from hell who have slept with like 75 guys, which brings the guys' average up to 7. So it all works out."

1. As I said, this is pretty stupid. Mathematically and otherwise.
2. Alas, there are no super-skanks. Or at least no more than there are on the male side.

All this really means, in the end, is that men over-report their number of partners and women under-report, which falls into the "New Study Finds College Binge Drinking To Be A Blast" department. Except it would have been nice if the sex researchers could have previously mentioned that their research proves people lie, not that guys get laid a lot.