One of the funniest things about being a tall, goofy person with a long history of wild gesticulation is that the more animated a conversation gets, the more likely I am to knock over a glass of red wine at a dinner table or accidentally wallop a stranger on the subway. Beyond being a real hit on dates or interviews, it’s an embarrassing piece of the growing pile of evidence that gestures are cognitive, an idea with an impressive amount of psychological literature behind it.

Traditionally, speech is framed as a love affair between mouth and mind, with no role for the rest of the body; there’s a reason that the people yelling on Fox News and CNN every day are called talking heads. Thanks to Rene Descartes and a pantheon of very serious dead white men, Western intellectual history has long maintained that thought is something that happens only in the kingdom of the brain; it’s just the body’s job, as educator Ken Robinson famously quipped, to bring the brain from meeting to meeting. But your hands suggest otherwise.

The University of Chicago psychologist Susan Goldin-Meadow has spent much of her career trying to grasp (yes, pun intended) what’s happening when people talk with their hands. As Goldin-Meadow defines it, “co-speech gesture” is different from action, like grabbing a cup of coffee or combing your hair, and it’s different from movement for movement’s sake, like in dance, ritual, or exercise.