“The tongue of a woodpecker can extend more than three times the length of its bill. When not in use, it retracts into the skull and its cartilage-like structure continues past the jaw to wrap around the bird’s head and then curve down to its nostril. In addition to digging out grubs from a tree, the long tongue protects the woodpecker’s brain. When the bird smashes its beak repeatedly into tree bark, the force exerted on its head is ten times what would kill a human. But its bizarre tongue and supporting structure act as a cushion, shielding the brain from shock.1 There is no reason you actually need to know any of this. It is information that has no real utility for your life, just as it had none for Leonardo. But I thought maybe, after reading this book, that you, like Leonardo, who one day put “Describe the tongue of the woodpecker” on one of his eclectic and oddly inspiring to-do lists, would want to know. Just out of curiosity. Pure curiosity.”