The world seems particularly enraptured with voice-based conversational interfaces: Siri, Cortana, Alexa, etc. As a Futurist-in-residence, I worked with an IDEO team to speculate about the next wave in human-computer interaction. Our answer: mimes, orchestra conductors, dancers, and sign-language experts. Gestures are faster, more expressive, easier to recall, and don’t sound as silly speaking to a computer when your friends are around. 3D cameras, computer vision, and neural nets make it possible to train your own gestural lexicon.