Mind & Body

The Tongue Map You Learned in School Is All Wrong

In grade school, you may have learned that specific zones of the tongue taste specific flavors. The very tip, for instance, tastes sweetness, and the back edges, by the molars, taste sourness. Well, we have an update for you: Though it's still getting published in science textbooks, that factoid's not true.

Meet the Mapmakers

The tongue map has its roots in a more-than-a-century-old German experiment. Scientist David P. Hänig, curious about taste perception, drizzled four flavors along the edges of volunteers' tongues: sweet, sour, bitter, and salty. (Westerners hadn't heard about the fifth flavor, umami, back then.)

Hänig focused on the edges of the tongue, specifically, because they're particularly dense with taste buds.

In a 1901 paper, he described his findings: Certain zones of his volunteers' tongues were more sensitive to certain flavors. For instance, it took less sweet drizzle on the tip of the tongue, typically, for a volunteer to perceive a sweet taste.

He graphed the relative flavor sensitivities around the edges of the tongue in a confusing way, though, and made the variation look more extreme than it actually was. A glance at his convoluted graph made the tip of the tongue look like the only zone that could taste sweetness at all.

In the 1940s, a Harvard scientist amplified this distortion even further, translating Hänig's graphed findings into the tongue map you're likely familiar with. He published the map without a legend in his book "Sensation and Perception in the History of Experimental Psychology."

From there, it took off in a surprising way. It was, after all, a map of a tongue made by a man named Mr. Boring — not an Ariana Grande single. The map's patchwork quality appealed to something primal and categorizing in people, though; stemware company Riedel even designed wine glasses with the tongue map in mind.

Unfortunately for wine enthusiasts, though, the tongue doesn't work like that.

The Truth About Tongues

It's not that no animal's tongue has that patchwork, compartmentalized quality. Fruit flies, for instance, taste with 32 hairs, and each hair senses a different flavor. Humans, though, don't work like that — probably.

Compared to the four other senses, there's a dearth of research on taste, so there's still some controversy around how taste even works and how many tastes there are. On a microbiological level, though, different receptors in our taste buds seem to taste different flavors. Each of our taste buds contains 50 to 150 receptors for each flavor.

In other words, receptors for all the flavors are distributed across the tongue and beyond. We have thousands of taste buds, in papillae, or tiny bumps, on our tongues, as well as on the roofs of our mouths and on the epiglottis, the flap that protects the windpipe. You can taste sweetness on the tip of your tongue, but also basically anywhere else in your mouth.

There is some regional variance in flavor sensitivity, researchers have found, but they've deemed it basically negligible. Hänig was onto something back in 1901 — but it wasn't that significant, and it certainly didn't legitimize the taste map of the tongue.

So the next time you want to taste something, don't look at a map. Your tongue knows what to do.

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Learn more about taste in "Flavor: The Science of Our Most Neglected Sense" by Bob Holmes. The audiobook is free with an Audible trial. We handpick reading recommendations we think you may like. If you choose to make a purchase, Curiosity will get a share of the sale.

Written by Mae Rice June 13, 2019

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