My Never Ending Battle With The Tongue Map Myth

This is my entry for Suesa's Science Challenge #2

My online friend @suesa asked us to write about a scientific misconception that either annoys or amuses us. Well, today I am gonna talk about something that creates both feelings to me.. But first let me tell you a story.

Our story begins about 23 years ago, with a 7 years old boy in Greece, reading another monthly issue of "Σαίνια" (rough translation: Geniouses).. Σαινια was a very popular kid magazine back at the days and probably the only kid magazine that had a large part devoted to science, DIY experiments, stuff like that.. 

So, our kid is reading the magazine and eventually comes across an article about the human mouth and how it works. One of the photos on the article is something you have probably seen at least once in your lifetime:

The famous tongue map. 1 tastes bitter, 2 tastes sour, 3 tastes salt, and 4 tastes sweet (source)

The article explained how the various part of the tongue can only sense a particular taste and called the readers to test this themselves using sugar or lemon. And that's what the boy did! He took a lemon and a suringe and dropped a few lemon drops here and there. To his surprise the juice tasted sour in all parts of his tongue! True, the taste seemed to be stronger in some areas, but still.. he could taste it on all parts of the tongue!

The article was spreading misinformation! The author hadn't even bothered to do the simple experiment he was asking the readers to do! What an idiot! The boy was proud!

Days passed..Years passed..The tongue map was something that came up every now and then in the boy's life. He would always tell other victims of the myth to just to do the experiment and taste the truth for themselves. Other kids like him were usually up to the challenge and were amazed by the results! However, adults or older kids would react with disbelief and say something like "What do you know? You are just a boy...".

More years passed. The boy was now a man but the tongue map myth still haunted him. It was like everyone believed this bullshit. And unlike in his childhood years, most people were no longer excited to do the tongue experiment and see the truth for themselves. They were growns up, too old for this shit.. too old to question a myth they believed to be true during their whole lifetime.....

Some more year pass.. The man is on a boring class in the second semester of his Food Science Master. The man is sleepy but the man has mastered all his mental power and tries his best to pay attention.. The class was on sensory evaluation or something, pretty basic and boring stuff..

I will let you in a secret now. The man is me. I remember sleepiness was getting the best part of me. Pure mental power no longer seemed enough to keep me awake. But the Professor is a real bitch so I have to stay awake, pretending to be excited with the stuff we see projected on the wall. *Click. One slide closer to the finish line. Click..another one... Click.. Click...

And then it happens! The sleepiness vanishes. My eyes are open wide. My blood is boiling.  My archenemy is there, on the fucking wall! The fucking tongue map! I hope she will start explaining how it's a myth and all.. But no, I know it's all wishful thinking.. But still... there is a fragment of hope in my heart. She starts talking and with her words she crushes the little hope I had... 

Here we are, in a food science Masters and a professor with more than 15 years of experience is spreading the fucking myth! I wonder.. How many students before me were taught this bullshit? How many believed it? How many actually wanted to say something but didn't, afraid of the repercussions?

I have to talk but I know I must not. It's just better if I shut up and move along with my life.. I know if I talk there will be consequences in the future so I let her finish.. But my feelings overcome me. I raise my hand. Here's the discussion that somewhat followed :

- Yes?
- Sorry but I have an objection on something you were just saying
- Which is? (ironic tone)
- This whole tongue thing. Actually it's a myth and there is no scientific proof behind it. Blah blah
- You have no idea what you are talking about kid. I am a professor and I think I know better than you
- Just do the experiment blah blah and see for yourself!
- Have you?
- Yes, you can taste all tastes in all parts of the tongue
- Then I guess you are a super taster [3] (she went full irony mode at this point)
- Look, don't take my word for it, after all I am just a kid. Just type in google tongue map myth. The first result is wikipedia. (Tries to interrupt me to say wikipedia is not a scientific source but I raise my voice). Check the second reference, it's a paper published a few years ago in Nature, sorry but I don't remember the exact name. Certainly I am a kid that doesn't know much, but I am sure the guys that got published on Nature are not (I can do irony too!)
- So you say that all the tongue experiments we have been doing in the very university you are attending came up with wrong results? (when you lose an argument just make up some bullshit)  
- All I am saying is that there is a recent paper on Nature [2] that totally disagrees with what you are teaching and I think you should check it out

The discussion continues for a while, essentially her calling me a kid, claiming how I know nothing about the topic and how she is an expert and all.. My response everytime was, "There is a paper on Nature, go check it out I would be happy to hear your scientific sources". Knowing it wasn't leading anywhere I just shut up saying something along the lines "let's agree to disagree"...

One month later, same professor, other course. When I saw her, I knew.  She had checked it up. She learned how the myth she was propagating all these years in her classes was just that, a myth. And she hated me for that. And I knew that if I dared to bring the incident up she would made sure I regret it. So I didn't. But another student did:

- Hey professor.. What about tongue map..blah blahblah...one month ago..blah blah blah..
- As I told you in the class guys, all parts of the tongue can sense all tastes!

Everyone's jaw dropped but no-one dared to say something. She pretended like the incident never happened... 

As expected, this incident came to bite me later in my studies.. But I won't be mentioning further details, I think that I have already said more than enough... At least I am happy to know that she won't be teaching that BS anymore..

The Tongue Map Misconception, How It Started And Why It's Wrong

The tongue map myth is a common misconception that is widely taught in schools all over the world and apparently in some universities too! But how did this myth start? Wikipedia does a pretty good explaining the hows and whys so I will just quote it cause I got tired from all the writing before:

 The theory behind this map originated from a paper written by Harvard psychologist D.P Hanig, which was a translation of a German paper, Zur Psychophysik des Geschmackssinnes, which was written in 1901.

The unclear representation of data in the former paper suggested that each part of the tongue tastes exactly one basic taste.

The paper showed minute differences in threshold detection levels across the tongue, but these differences were later taken out of context and the minute difference in threshold sensitivity was misconstrued in textbooks as a difference in sensitivity.

While some parts of the tongue may be able to detect a taste before the others do, all parts are equally capable of conveying the qualia of all tastes. Threshold sensitivity may differ across the tongue, but intensity of sensation doesn't.

The same paper included a taste bud distribution diagram that showed a "taste belt", similar to a "waste belt" but for your tongue.

In 1974, Virginia Collings investigated the topic again, and confirmed that all the tastes exist on all parts of the tongue. 

So that's pretty much all I had to say about this misconception. Have you fallen a victim to this myth? Let me know in the comments below :)

References

1. https://en.wikipedia.org/wiki/Tongue_map
2. https://www.nature.com/nature/journal/v442/n7105/full/nature05084.html
3. https://en.wikipedia.org/wiki/Supertaster