Different parts of your tongue taste different things
The old claim turned out to be wrong and was rejected by evidence.
TaughtThe tongue map: sweet at the tip, salty and sour along the sides, bitter across the back.
NowAll taste regions of the tongue detect all basic tastes. The map came from a mistranslation of a 1901 German paper, and there was never good evidence for it.
What actually happened
The tongue map traces to a 1901 dissertation by David Hänig, who found very slight differences in threshold sensitivity across the tongue. In 1942 the Harvard psychologist Edwin Boring rendered his data into a chart in a way that turned tiny variations into hard zones, and the chart was too tidy to die. Virginia Collings demonstrated in 1974 that sensitivity to all tastes is present everywhere on the tongue with only minor variation.
The modern picture is molecular: taste receptor cells sit in buds distributed across the tongue, palate, and throat, and individual buds contain cells responding to multiple tastes. Textbooks kept printing the map into the 2000s anyway, which makes it the single best example on this site of how long a good diagram can outlive its evidence. You can test it yourself in about ten seconds with salt and the tip of your tongue.
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Sources
- Nature: The tongue map: tasteless myth debunkednature.com
- Smithsonian Magazine: The tongue map is a liesmithsonianmag.com
Who was taught this
Still standard through 2005, so anyone who finished school between 1950 and 1993 learned the earlier version.