Susan Goldin-Meadow is a professor in the department of psychology and comparative human development at the University of Chicago. She is the author of Thinking with Your Hands: The Surprising Science Behind How Gestures Shape Our Thoughts. We all move our hands when we talk. We do it in all cultures, when we’re young and when we’re old. Individuals who are blind from birth also move their hands when they talk even though they have never seen anyone gesture, and do it even when they are talking with other blind individuals. Most people think these movements are meaningless handwaving, or...