Our tongues can sense five basic tastes with specialized nerve cells for each: salty, sour, sweet, bitter, and umami (savory). But a new study suggests our tongues can detect another “taste”—tasteless water. A paper published in the journal Nature Neuroscience details this fascinating new research, which uses mice as the test subjects.
According to a press release from the researchers,1 when the mice tongues were stimulated with pure water, the nerves responded, suggesting that somehow their (and presumably our) tongues can indeed “taste” water. Researchers then genetically and pharmacologically blocked the taste receptors for various flavors, such as saltiness. When the mice with the blocked saltiness taste receptors were exposed to something salty, they no longer responded because they could no longer taste the saltiness. To the complete surprise of the researchers, when they blocked the sour taste receptors, the mice no longer responded to water.
To look into this surprising result further, the researchers used a technique called optogenetics. This allowed them to stimulate the sour taste receptors using light, rather than water. Instead of dripping water, the mouse’s water bottle emitted a blue light when a mouse touched it. Because the light created a sensory cue for water, these thirsty mice eagerly “drank” the light for up to 2,000 licks every 10 minutes,2 even though they weren’t being hydrated.
Researchers also found that when mice were given the choice of water or a clear, tasteless, synthetic silicon oil, the mice who had been engineered to lack sour taste receptors took longer than other mice to figure out which drink was water.3
This shows that the taste receptors on mice tongues don’t tell the mice when they’ve quenched their thirst, but they do let them know that what they’re drinking is water which, according to neuroscientist Zachary Knight, must be sending the brain information “because animals stop drinking long before signals from the gut or blood could tell the brain that the body has been replenished.”4
These study results haven’t been replicated in humans yet. However, since insects and amphibians can detect water and since this ability has been found in mammals, it seems likely that something similar is occurring on our tongues, letting us know what we’re drinking really is water and will adequately quench our thirst.
The design of water is very helpful to mankind. Because water is considered tasteless, we can cook with it without affecting the flavor of our food. And, based on this new research, it appears God specifically designed mammals to “taste” water even though it’s tasteless, thus protecting us from drinking nonaqueous liquids and failing to properly quench our thirst. He’s designed our bodies to be compatible with the water he also designed for our use. What a wise Creator we serve!
Next time you grab a glass of ice cold water or fill a pot to make dinner, stop and thank the Creator who gave us such a wonderful gift and has so fearfully and wonderfully designed our bodies.