It’s one of the world’s most famous maps, along with that of the New York City subway system and the one for the Game of Thrones world: the map of your tongue. You probably saw it in high school, and learned that your loquacious mouth muscle is neatly divided into sections responsible for tasting sweet, sour, salty, and bitter.
You learned very wrong.
The myth of the taste map goes back to the early 1900s and a German scientist named David Hänig, whose experiments found that the tongue is particularly sensitive to tastes along the edges, and not so much at the center. Which is true—modern science backs that up. “But this has been converted down the years into a more extreme version of the taste map that says sweet is at the front of the tongue, bitter is at the back, and salty and sour at the sides,” says Robert Margolskee, director and president of Philadelphia’s Monell Chemical Senses Center, which researches taste and smell. “And that is totally incorrect.”
The reality is that the different tastes are sensed by taste buds all over your tongue. Each taste bud has 50 to 100 taste receptor cells that respond to different qualities, like salty, sweet, and another that isn’t on the old map at all: umami. That’s the savoriness associated with amino acids, like those in cooked meat or mushrooms.
Working in concert, the receptor cells keep us alive by making us crave or abhor certain edibles. (Or, inedibles.) You like sweet things because long ago in our evolutionary history, our ancestors needed fruit for nutrients and easy calories. On the other hand, a bitter taste in some plants is a warning of toxicity. Our ancestors who were the best at detecting bitterness—and thereby not poisoning themselves—passed on their genes for sensitivity to it.
But wait, why do highly bitter liquids like IPAs and coffee and tea taste so damn good to us modern humans? “Younger children tend to be very sensitive to bitter,” says Margolskee. “But with time we can learn that, hey, that bitter stuff is not really bad. I can associate it with a very positive effect—for example, those who like beer for the alcohol buzz.”
Across the animal kingdom, each species’ unique evolutionary history creates unique taste abilities. Carnivores, for instance, don’t eat fruit, so they don’t have our craving for sugar. “Cats actually cannot taste sweet,” says Margolskee. “And so if you give a cat vanilla ice cream and your cat likes it, the reason they like it doesn’t have to do with the sugar. They presumably like it because of the fat, or maybe the amino acid umami component of it.”
Yum. To learn more about the delectable science of taste, check out our video with Margolskee above.
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