Most of us pass our lives never once laying eyes on our organs, the most precious and amazing things we own. Until something goes wrong, we barely give them thought. This seems strange to me. How is it that we find Christina Aguilera more interesting than the inside of our own bodies? It is, of course, possible that I seem strange. You may be thinking, Wow, that Mary Roach has her head up her ass. To which I say: Only briefly, and with the utmost respect.