Let’s be blunt: The tongue is really dumb. Unlike the rest of our sensory organs, which are exquisitely sensitive, that lump of exposed muscle sitting in the mouth is a crude perceptual device, able to only detect five different taste sensations. (Your cochlea, in contrast, contains thousands of different hair cells, each of which is tuned to particular wavelengths of sound.)

What makes the tongue even worse is that we have no idea how useless it actually is. Instead, we are convinced that the tongue is remarkably sensitive, able to perceive all sorts of subtle flavors. That’s why we r...