"Think of a peanut between two molars, about to be crushed. At the precise millisecond the nut succumbs..."

"... the jaw muscles sense the yielding and reflexively let up. Without that reflex, the molars would continue to hurtle recklessly toward one another, now with no intact nut between. To keep your he-man jaw muscles from smashing your precious teeth, the only set you have, the body evolved an automated braking system faster and more sophisticated than anything on a Lexus. The jaw knows its own strength. The faster and more recklessly you close your mouth, the less force the muscles are willing to apply. Without your giving it a conscious thought."

Mary Roach writes about the science of chewing. She's a wonderfully fun writer. I've read 2 of her books — "Stiff" (about dead bodies) and "Bonk" (about sex) — and her new book is "Gulp," which I just pre-ordered for my Kindle. (As long as we're pre-ordering... "Let's Explore Diabetes with Owls.")

And here's "Gulp! The Quiz," where I learned that a certain celebrity had a "megacolon" — a colon two to three times normal size.