The unlikely Exhibit A: Crohn’s disease, a chronic inflammation of the bowel that is on the rise in developed nations. Crohn’s and other autoimmune disorders are most common in exactly those places where public health seems to be most advanced—where, for instance, the intestinal parasites that plagued humans for much of history, such as hookworms and tapeworms, have become staggeringly rare. What if, scientists wondered, the absence of these parasites was somehow leaving us more vulnerable to various maladies of the immune system?
It's one thing to be neat and clean. It's another to obsess over cleanliness. My grandmother used to say that you need to eat a bushel of dirt before you die. Forget about trying to keep looking young, or trying to live as long as possible. None of it's worthwhile if you don't know how to enjoy living in the first place.