The power of love is (as the song says) a curious thing. Rock stars sing about it, comedians tell jokes about it, and just about every advice columnist writes about it. Scientifically, however, just how curious love is, is still an open question. "Love" is a four-letter word to many people-and "sex" is the shortest four-letter word of all. Society builds taboos around these words, but there's no denying that love and sex are spectacular. ...