Is There a Tongue Map?
written by Rafael Hoekstra and Les Kuan
Back in 1901, a German scientist named D.P. Hanig developed a map of the tongue map by asking volunteers where they could perceive sensation. Other scientists later corroborated his findings but charted the results in such a way that areas of lowered sensitivity looked like areas of no sensitivity.
Today, it seems that the situation of where taste takes place is less clear than ever. It turns out that the beloved tongue map many of us learned in school - which shows bitter tastes are detected in the back of the tongue while sweet tastes are detected at the tip- has no scientific basis.
Photo credit: MesserWoland, CC BY-SA 3.0, via Wikimedia Commons
The first tongue map: 1. Bitter; 2. Sour; 3. Salty; 4. Sweet
By 1974, Virginia Collings had determined that while the tongue did have varying degrees of sensitivity- some areas could perceive certain tastes better than others- there was no real truth to the strict tongue map.
As we understand now, although taste receptors usually react strongly to a single taste, many respond to multiple gustatory stimulations. People can perceive taste anywhere there are taste receptors. Scientists are also learning more about the shocking diversity of taste sensitivity...
In 1991, Linda Bartoshuk, then of Yale Medical School, coined the name "supertasters" for the people with acute taste sensitivity and noticed that they had a denser covering of fungiform papillae than nontasters. She linked the number of taste receptor cells to supertaste. Usually for these studies, a chemical compound such as phenylthiocarbamide or propylthiouracil is used, as people report differing abilities to taste these. Based on these studies, it is estimated that 25% of the population are nontasters, 50% are medium tasters, and 25% are supertasters 1.
photo credit: Sensonet, CC BY-SA 3.0, via Wikimedia Commons
How does the tongue map relate to coffee?
Current research suggests that people’s perception of bitter tastes, such as that of caffeine and other compounds found in coffee, is affected both by their diet and by their genetics2. The daily consumption of coffee indicates a stronger perception of bitterness, as does the abundance of Bitter Receptor mRNA. In summary, there is a real basis for the differences in perception in coffee taste, caused by both genetic and dietary factors.
All of this contributes to the complex range of flavors experienced when drinking coffee.
References:
- David V. Smith; Robert F. Margolskee (March 2001)."The Taste Map: All Wrong". Scientific American.
- Lipchock SV, Spielman AI, Mennella JA, et al. Caffeine Bitterness is Related to Daily Caffeine Intake and Bitter Receptor mRNA Abundance in Human Taste Tissue. Perception. 2017;46(3-4):245-256. doi:10.1177/0301006616686098.
https://en.wikipedia.org/wiki/Tongue_map
