Surveys consistently report that men in the U.S. population average seven sexual partners, while women average four. Everyone assumes men are cads and women are out to protect their virtue, so this makes perfect sense, except...
"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(EQUAL)B "Proof: Both G and B are equal to C, the number of couples who danced together at the prom. QED."
In other words, unless U.S. men are having tons and tons of sex with women who are outside the survey population (trips to foreign countries? prostitutes who don't tend to show up in these surveys?) it's mathematically impossible for men to average more sexual partners than women. Rather, as Sevgi Aral of the CDC and David Gale, an emeritus professor of matehmatics at UC Berkeley assert in a recent piece in the Boston Globe, "...men exaggerate the number of partners they have and women underestimate." That couldn't be because of the aforementioned culturally-ingrained notions about the respective roles of men and women in the mating game, now could it? Spotted on Echidne of the Snakes Update: See the comments for a discussion about mean (average) vs. median in the case of these statistics. Turns out things are not so simple as Dr. Gale's simple proof would lead us to believe.