When your parents taught you about the birds and the bees, they probably didn't go into that much detail. Although sex is one of humankind's most important and popular activities, we still get squeamish talking about it. That's part of why there has been relatively little research into its science - the physiology and mechanics of how sex works. But there has been some, and it's laid out in detail in a new book called Bonk: The Curious Coupling of Science and Sex. It's by science writer Mary Roach, who even participated as a guinea pig in a research study. That's right - she had sex for science. Mary Roach speaks with Faith Salie on Fair Game.