Early on in every relationship the toilet seat issue rears its ugly head. Usually this manifests itself in a single question: "Why won't he leave the seat down?" Well science has come to the rescue in the form of Jay Pil Choi, an economist from Michigan State University. He published a paper in 2002 called "Up or Down? A Male Economist's Manifesto on the Toilet Seat Etiquette". The brief summary of the paper's conclusions is that unless it is much more inconvenient for one gender to change the seat position, the selfish rule - whereby the seat is left in whatever state the last user needed it - is the most efficient in terms of overall convenience... But then we already knew that guys, didn't we? ;-)