When I was a kid, my brother and I loved playing with toy dinosaurs. I’d let my brother take the ever-popular T. Rex while I went for the stegosaurus. Its back plates and tail spikes were cool, but it was this dinosaur’s second brain that put it over the top for me. I think I intuited at an early age that two brains are a good idea in the scheme of things. Frankly, in the years since, I’ve often suspected that my tongue has a brain of its own. How else to explain what sometimes comes out of my mouth—words that, if given even modest scrutiny by my brain, would be judged to make no sense; words that can be as sharp as the spikes on the stegosaurus’s tail; words that make a good case for a second brain dedicated to the nonthinking function of the tongue.