Another great collection of New Scientist columns with readers asking questions and other readers answering them. Lots of interesting trivia; two different answers given for why we westerners tend to eat a sweet course at the end of the meal (not totally sure I believe either of them); the title question is answered somewhere in the middle; at the very end, a question about how Big Ben is kept on time is answered by someone who had actually had the job of keeping it on time. Entertaining stuff.