Surprising Facts About Your Tongue: Beyond Taste, Talking & Kissing
Surprising Facts About Your Tongue: Beyond Taste, Talking & Kissing
And forget surprising – one of the most shocking facts about the tongue is that you can actually be born without one.
More astounding are the two professors at Cal State suggesting we may not need one to taste, or to talk.
Congenital aglossia is this rare condition and worldwide, there are only 11 medically recorded cases since 1718. Even tripling that with the assumption there would be cases not noted, it’s still a strikingly miniscule number in reference to the 7,184,798,739 people born since then.
Born in 1969, Kelly Rogers belongs to this exclusive world grouping and Betty McMicken, associate professor in the department of Speech-Language Pathology, along with Long Wang, assistant professor of nutrition in the department of Family and Consumer Sciences have established that Kelly – able to speak since childhood – can also detect all basic tastes.
McKinnon and Rogers first met in Santa Ana, 1986 at Western Medical Center to see if doctors could reconstruct the 16-year-old’s jaw. It was concluded then, that since Kelly was using her mouth and throat muscles to speak, that surgery could have an adverse affect.
Twenty-five years later the two reconnected, and Rogers eventually became McKinnon’s research assistant.
Without having had any medical intervention, the muscle mass of the floor of Kelly’s mouth has strengthened through years of speaking. Other structures of her mouth contract and relax, and she is able to touch this muscle to her palate.
Rogers is a unique case, and continued studies will prove invaluable for people who require partial or complete removal of their tongue. The more that’s known, the more surgeries and procedures improve.
Kelly’s tastebuds are perfectly normal; she too has them on the base of her tongue and inside of her cheeks. The research confirmed for her that her ability to taste the full range of flavours is not through texture or smell as she had always been told.
Kelly can eat everything, even ice-cream cones, by simply using her lips. She has difficulty biting an apple, but that’s due to her smaller jaw and its resultant misalignment due to not having a tongue to broaden that space.
What’s it like kissing without a tongue? “Well, I like to kiss,” she says, “and I’ve been told I’m a good kisser; I’m sure it’s different, but I’ve had no complaints.”
In humans, prior to the Cal State study, the tongue was always considered absolutely essential for speech, moving food in the mouth, and as a taste and texture sensor. Microscopically, the surface of the tongue is an extraordinary topography of thousands of tiny papillae, housing taste buds and providing friction and lubrication. These studs of fringed and bumpy buds sense the five basic palate sensitivities: salty, sweet, sour, bitter, and umami.
Understanding the mechanical interaction of the tongue and what we consume facilitates food scientists, drug developers and manufacturers of oral care product to produce more appealing merchandise.
Since ancient times, there has been the philosophical claim that water has no flavour. Aristotle referred to water as being “tasteless” around 330BC, and most of us will have had the experience of this not being true: most definitely for those who’ve had the pleasure of Swiss tap water, the pure water of New Zealand. It’s a good ol’ drop in most Aussie places, and most particularly in Mackay. Unsurprisingly Iceland is deemed as having the purest, best tasting tap water in the world. Equally there’s the shock of unpleasant water tastes from the tap: Perth and Adelaide are pretty awful, and Reno, Nevada is ranked worst in the world. The more than 11 contaminants attest to that; including arsenic, manganese, and tetrachloroethylene, at levels exceeding EPA limits.
Insects and amphibians have water-sensing nerve cells and there is growing evidence of similar cells in mammals. Patricia Di Lorenzo, a behavioural neuroscientist at the State University of New York in Binghamton suggests mammalian tastebuds have an additional sixth sense for water. It helps explain how animals differentiate water from other liquids.
And it adds new fodder to a centuries-old debate of whether water has a taste of its own, or is merely a vehicle for other flavours. Critics argue that any perceived taste is just the after-effect of whatever was earlier consumed.
Lorenzo’s recent study shows brain scans suggesting a region of the human cortex that responds specifically to water.
Logic dictates that the brain must somehow receive water information from the mouth and tongue, because animals stop drinking long before signals from the gut or blood can tell the brain that the body has been replenished.
Zachary Knight, another Cal State neuroscientist and his team have found distinct neurons within the hypothalamus that trigger thirst, and signal when an animal should start drinking, and when it should stop. Prior to this, almost nothing was known about the molecular and cellular mechanism by which water is detected in the mouth and throat, or the neural pathway by which that signal is transmitted to the brain.
In an attempt to settle the water-is-tasteless debate, neuroscientist Yuki Oka and his team at Pasadena’s California Institute of Technology, searched for water-sensing taste receptor cells (TRCs) in the mouse tongue. Professor Oka interest is in the neural and molecular motivators of homeostatic regulation. The long-term goal is to understand how the brain integrates internal body state and external sensory information, to maintain homeostasis.
Homeostasis is the crucial survival function that keeps a consistent and optimal internal environment. If an internal state shifts, the brain detects the change and triggers compensatory hormonal responses and secretion and intake behaviours. The two questions driving this ongoing research are: How does the brain monitor internal state; and how does are the appropriate responses generated?
Genetic knockout mice were used in the research to look for the cells. Different taste receptor cells (TRCs) were silenced, and the rodents’ mouths were flushed with water to see which cells responded. The most surprising part of the project was that the well-known, acid-sensing, sour TRCs fired vigorously when exposed to water.
When the option of drinking either water or a clear, tasteless, synthetic silicone oil was given, mice lacking sour TRCs took longer to choose water. It suggests that these cells help distinguish water from other fluids.
Using a technique called optogenics, the team tested whether artificially activating the cells could induce the mice to drink water. They bred mice to express light-sensitive proteins in their acid-sensing TRCs, which made cells respond to laser light.
After training the mice to drink water from a spout, water was replaced with an optic fibre that shone blue light on their tongues.
When the mice “drank” the blue light, they behaved as if they were tasting water. Some mice thirstily licked the light source as many as 2000 times every 10 minutes.
There’s a particular cruelty to science that should never be simply accepted with impartial disregard; these are living creatures that are manipulated on cellular and behavioural levels. In just one year in the US alone, 100 million vertebrates are used in research and only 3% survive.
Of these millions, 15% are not frogs, rats, mice, birds or fish, but cats, dogs and primates.
In order to learn more about humans, we somehow become less so in the doing.
These poor mice never learned the light was an illusion, and kept drinking long after those drinking water did. It suggests that although signals from TRCs in the tongue can trigger drinking, they play no role in telling the brain when to stop.
Research continues in order to precisely determine how the acid-sensing tastebuds respond to water, and what the mice experience when they do. Oka suspects that when water washes out saliva – a salty, acidic mucus – it changes the pH level of the cells, making them more likely to fire.
The notion that animals detect the need for water by lack of saliva seems obvious: after all, a dry mouth is certainly how we determine thirst. But it’s still just one of many likely routes for sensing water, which includes temperature and pressure.
These types of studies also speak to the long-standing debate over the nature of taste. A tastebud has around 50-150 receptor cells for discerning flavour. Each receptor can sense only one: sweet, salty, sour, bitter, umami or a potential of other tastes, including fatty.
When there’s a counter example to the dominant view of only five tastes, scientists go back to the drawing board and with sophisticated computer systems, mathematical models, human tissue and cell cultures that can reveal the reactions and responses of the human body, the use of animals is still preferred with all its trauma and death. Tests and conditions unlawful on humans because they’re deemed inhumane.
The use of animals in research is certainly never undertaken lightly; researchers carry out experiments with extreme care to eliminate or minimise suffering. However, somewhere there may be a karmic price to pay in the way we continue the torture of animals in the name of research and production because we regard ourselves as the most important inhabitants on the planet rather than the most iniquitous and destructive.
Some food for thought while we’re dealing with taste.
Researchers at Oregon State University have discovered how people fundamentally detect flavour, and why some foods are immensely more enjoyable than others.
The findings are hoped to lead to the ultimate goal of nutrition – having people really like vegetables. Which is pretty pathetic, really; you don’t have to like something to know it’s good for you. And palates change. Through adventure, age and experience. Ostensibly it seems to be more consumer pandering and yet another chance for a corporation to patent yet another thing that could never be owned before.
Who knows – one day you may not own your own tastebuds. Some have already signed them over to fast food, fried feasts, finite fresh fruits and frozen fare; maybe research like this heralds the beginning of formalising, digitising, personalising, dehumanising and franchising that somehow.
As an evolutionary survival mechanism, Homo sapiens were wired for sweet-tasting foods. As hunter-gatherers, foods that were sour or sharp warned of the possibility of poison. Sweet or salty were usually safe to eat and provided macronutrient carbohydrates and salt.
Predominantly, commercialism has exploited that highly useful trait. It brainwashes and convinces us that in exchange for its exponential wealth and influence, global ill-health and the training of gluttony is a fair trade.
Planes have crashed because we can’t stop stuffing food in our mouth. Calculating average passenger weight that is imperative to aircraft lift, had not been accurately reassessed for almost 50 years. Assumptions of average weight had to be increased by 15kg.
Beyond diet and exercise, Professor Jennifer Kuk of Toronto’s York University proffers three specific contributors to take into account for this substantial increase in the rise in obesity.
Firstly, there is consistent and increasing chemical exposure to substances that alter hormonal balance. Flame retardants, pesticides, phthalates, parabens, PFAs and bisphenols are in everything. Just the daily use of personal care products alone contain 129 unique chemicals.
Overall, fewer than 1% of chemicals used in consumer products have been rigorously tested for human safety.
Secondly, is the use of prescription drugs. Antidepressants are now one of the most commonly prescribed drugs in the western world and they are most certainly linked to weight gain.
Finally, Professor Kuk thinks that microbiomes have changed since the 1980s and it’s now known that there is a specific gut bacterium that promotes weight gain and obesity. Meat is eaten more often now than 40 years ago, and there’s a cumulative effect of agricultural hormones and antibiotics on gut microbiomes.
Kuk also believes the proliferation of artificial sweeteners is a negative contributor.
The tongue helps us taste food, and sense textures – a very important aspect in the sensuous savouring of a meal. Manufacturers clap their greasy, sugar-dusted hands in appreciation of decades of research into the pleasure of texture and taste, and interference of the satiety cascade.
Once you pop you can’t stop.
Tongue texture is made of papillae, with each one the site of multiple flower-shaped tastebuds. Each tastebud regenerates every two weeks, which is why we recover quickly from the mouth burns of hot food or drink.
Aging takes tastebuds with it, and explains why the elderly prefer blander foods because by then, the 10,000 tastebuds we’re born with are halved.
The American Chemical Society’s peer reviewed publication ACS Applied Materials & Interfaces reports that a 3D silicone surface has been made that for the first time, which closely mimics the surface features of the human tongue.
Currently, scientists rely mainly on human tasters to assess texture, or that eye-rolling irksome term ‘mouth feel’, and it’s time-consuming, subjective and expensive. Electronic tongues, or e-tongues exist, but they analyse taste only, because of the previous gross inaccuracies in the development of texture. Professor of Colloids and Surfaces, Anwesha Sarkar and her colleagues at the University of Leeds have developed a soft 3D surface that replicates the topography and saturation of a human tongue.
Silicone masks were made of the tongue surfaces of 15 healthy adults. 3D optical scanning and computational surface reconstructions created digital models with average density, diameter and height of the two major two types of papillae. A master mould was designed, with the appropriate spatial distribution of these papillae and it was 3D printed. A soft, tongue-like surface of silicone was made and a surfactant added for saliva-like qualities.
This 3D biomimetic surface demonstrated similar frictional properties to a human tongue, and simulates comparable mechanical sensing properties. The team’s endeavour with this tongue-like surface is to support the accelerated development of biomedical, nutritional and clinical products, as well as its application in soft robotics.
No doubt there is a near future of retinal, finger, and tongue scans for identification and there’s cold comfort in imagining simultaneously giving Big Brother the evil eye, the finger, and poking out your tongue.
Most recently in the journal Chemical Senses scientists have outlined exactly how humans use nose and tongue to recognise foods that are safe to eat. When aroma and taste are congruent, like vanilla and sugar, the brain processes it as one sensation that is coming from the mouth.
Vanilla has no taste at all. It’s a smell; and the pleasant sensation comes not from your mouth but your nose – the act of chewing pushes air through the passage at the back of the throat.
When flavours are incongruent and not as commonly found together – like vanilla and salt – then the sensation is that vanilla is from the nose, rather than tasting it in the mouth.
There are several senses involved in perceiving flavour. Taste, solely from the tongue; smell, exclusively to the nose; and somesthesis, which includes things like texture, temperature, and the burn of chilli. Even though the mouth and nose are closely connected, taste and smell don’t physically interact with each other there at all.
As with our entire perception of the world it all happens in the brain.
Both taste and smell are linked through the body’s chemosensation, a system that includes mouth, nose, eyes and throat. In the orbital frontal cortex, taste and smell integrate to perceive a single flavour. The verdict is relayed back to the tongue and an imprint of flavour, with the idea it has come from the mouth, is given.
It’s the reason we hold our nose when taking something unpleasant. Sip a favourite beverage while pinching your nose and notice the taste. Unfamiliar? Open your nostrils and the flavour reappears.
Substituting unhealthy with healthy would be an interesting experiment. Foods you’d like to give up, and foods you dislike but are healthy should simply be eaten while wearing a nose clip.
Even so, flavour perception is largely a learned behaviour. If you haven’t had Vegemite by the time you’re two, more than likely you’ll never, ever like it and every culture will have particular foods.
Since it’s learned, and according to Michael Mosely nurture outweighs nature in the nutrition stakes, we should simply learn better habits based on the better information we have. We find ways to work around evolutionary instincts all the time. It’s an evolutionary instinct to be lazy. It’s an evolutionary instinct to sleep when the sun goes down.
It’s an evolutionary instinct to live in a tribe.
Taste is foundational to human function, and it’s not a static sense. Human Molecular Genetics recently noted our involuntary response to bitter stimuli has reduced; we enjoy coffee and alcohol that our ancestors would reflexively rejected.
So we’ll change these things and we’ll bend these things and we’ll be broken of these things when profits in the billions are to be made. When the easy betterment of global health is tabled, the fork-tongued lip service from the mouthpieces of power is gobsmacking.
Advances in science and medicine skew our survival instinct, sexual and social instincts are constantly debated or legislated, so it’s as convincing an argument as fracking, that the-ape-in-me-made-me-do-it.
With all the technology, available data, and the astounding breadth of research, and with all the logic we insist is inherent we’re still just making a monkey of ourselves. Humanity lives with the possibility of nuclear apocalypse or worldwide war because we’re not cave dwellers and it absolutely proves we are.
We claim the internet, space exploration, artificial intelligence and neurosurgery because we’re not cave dwellers. We blame the overconsumption of cheap, sugar-swollen, low-nutritional, earth-damaging foods because we are.
On the evolutionary scale we’re an overnight sensation.
Although true, it’s a redundant excuse for nutritional preferences from the five fast food groups. Evidence suggests that toxin taste avoidance strategies evolved with the use of fire, so there is that. Flavour perception no longer saves us from being poisoned, it leads us by the nose to the water we won’t drink and the soft drink we do.
In a Sydney suburb, residents are fighting plans for the construction of a 24/7 McDonald’s based on the negative impact of that signature smell. Part of the objection is its permeation of “a peaceful evening breeze.”
Just the mention of it has your nose fill with its familiarity, hand-in-hand with a miffing Mac craving. You see it forever sauntering from sunset to sunrise throughout the gentle winds, as is the big Mac corporation’s wont.
The first time the somewhat bitter taste of black coffee is tasted, few like it immediately, but the effect of the caffeine overrides and the like for the flavour is learned.
As the mechanisms underlying the process of taste unfold, it is hoped the knowledge will move people toward improved food choices from sustainable and ethical food production, without compromising too much on taste.
These are luxuries of thought not afforded the Russians in Leningrad in 1941 where the survival mechanism pushed limits not many would willingly put to the test. Taste was the least of their concerns, and the Fijian term puaka balava meaning ‘long pig’ is apparently most apt.
It’s the incredible flexibility of the tongue that allows the formation of shapes for sound, gives the pleasure of kissing, offers the multi-uses of licking, the necessity of moving food around the mouth, and the ability to both stop things going down your throat, and swallow them.
You can clean your teeth with your tongue, insult people with it, you can have sex with it, few people can profile a clover with it, and not everyone can roll it.
Is it genetic?
Those enthusiastic yeses are heard; despite the answer being ‘no’ – and here’s why: Scientist Alfred Sturtevant conducted a study in 1940, and claimed the results favoured genetics. However, his study was extremely flawed. Some of the participating kids refused to open their mouth, so he included them in the “not able to roll their tongues” category. Sturtevant also documented that some children could roll their tongues and neither parent could, which alone disproves his genetics hypothesis.
Other studies discount Sturtevant’s findings, and he probably spent the remainder of his days eating alone in the cafeteria, claiming self-funded research on diet and academic achievement, and attempting to reinstate the Taste Map.
The Journal of Clinical & Diagnostic Research published a study indicating that the language you speak is a factor in tongue movement and rolling ability. Hardly surprising really; and nice to see it being documented.
The study involved 450 medical students from three ethnic groups: Malay, Malaysian Chinese, and Malaysian Indian. Each participant spoke several languages.
The most versatile tongue movements were by Malaysian Indians, bringing the conclusion that intricate shape and movement ability is the result of linguistic demands. So as with taste, tongue flexibility can be learned. It is after all, a muscle.
And a surprising muscle at that. It has been known to generate a sound level of 114.2 dBA.
A lawnmower is 90 dBA and a car horn is 110.
The most variant shape in the mouth is found in the epiglottis, and the only real variation in tongues is length.
Gene Simmons, Nick Afanasiev, Demi Moore and Kelly Rogers could have an interesting chat about that.
Note: All content and media on the Sunbury Dental House website and social media channels are created and published online for informational purposes only. It is not intended to be a substitute for professional medical advice and should not be relied on as health or personal advice.
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