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You probably know not to lick something unfamiliar. But there are actually a surprising number of discoveries that have been made because scientists licked things.

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[ INTRO ].

How many licks does it take to get to the center of a Tootsie roll centered Tootsie Pop? I don’t care!

But that doesn’t mean scientists haven’t tried really hard to find out. The results are — sadly — very inconclusive. But there are actually a surprising number of other discoveries that have been made because scientists licked things that they… maybe shouldn’t have?

Here are seven times licking stuff has — amazingly — helped the scientific process along. This first example is actually three discoveries in one. Because, believe it or not, scientists have discovered artificial sweeteners by licking chemicals... not once, not twice, but three separate times.

All because they were really bad at washing their hands in the lab. First, there was saccharin, the sweetener you probably know by the brand name Sweet’N. Low.

It was discovered in 1897 by a grad student who was trying to find something useful to do with a waste product of coal processing called coal tar. After a day in the lab, he went home and notice the bread he was eating tasted strangely sweet. As did his fingertips, and everything else he touched.

So obviously he went back to the lab and tasted everything on his lab bench to try and solve the mystery. Oh, sorry, you don’t think tasting everything on your bench devoted to studying COAL WASTE. PRODUCTS is a good idea?

That’s weird. Once he figured out that saccharin was the culprit, he wanted to make sure it was safe. he went ahead and ate 10 grams of it and waited to see what would happen to him. Fortunately, nothing happened, and even though saccharin is known to have a bit of a weird aftertaste, it became really popular in the U.

S. during World War I, when sugar was scarce and conserving it was considered patriotic. It’s also still widely used today. That’s not the case for sodium cyclamate, another artificial sweetener that was discovered in 1937.

It was banned in the U. S. in 1969, after it was shown to cause bladder cancer in rats and chicks — although today, the validity of those results is debated. [on pic] Regardless, its story started off in a similar way, with a grad student trying to synthesize an anti-fever medication. One day, he was smoking in the lab and tasted something sweet when he happened to brush some loose tobacco off his lips.

And suddenly, artificial sweetener. Also, Smoking in the lab! The final sugar substitute on this list is aspartame, which was discovered in 1965.

The researcher who found this one was trying to create a drug to treat gastric ulcers. He’d gotten some of what he was synthesizing on his hands and forgotten to wash them. So when he licked his finger to pick up a piece of paper, he noticed it tasted super sweet.

Now, he had washed his hands since breakfast. Honestly surprising, given this lot’s track record. So he knew it couldn’t be sugar.

And once he’d traced it back to the compound known as aspartame, he made an educated guess that it probably wasn’t toxic and tasted it. Today, it’s often what’s used to sweeten diet soda. For plenty of people, these three discoveries were life-changing… but if you work in a lab, please follow the safety procedures and don’t, just lick stuff.

If salty snacks are more your style, we’ve got a “scientists fail to wash their hands” story for you, too. Around 2013 or so, group of scientists was hanging out in Australia. They were collecting samples and reclassifying a genus of wild grasses called spinifex into different species.

Obviously, this involves making lots of observations about the grasses, but even so, tasting them wasn’t in the plan. As the researchers later put it when they talked to NPR, “It's probably not the best way to explore the natural world, licking things.” Yeah, no kidding. But a couple of the grass species happened to have sparkly droplets of sap on them.

And back in the lab, some of the sap got on one of the researchers’ hands, which she later happened to touch to her mouth. Surprise! It was tangy in a way that the researchers said they recognized: It tasted just like salt and vinegar chips.

Sadly, the rest of us probably won’t be snacking on spinifex anytime soon. It’s a tough and spiny plant, and when the researchers later licked the actual grass to prove that it caused that taste… they said it felt like licking a porcupine. Which, how did they know?

Maybe they licked the porcupine. Anything on the table at this point. They didn’t end up investigating what made the sap taste so tangy, and they also didn’t mention the flavor in their 2017 paper.

But they did make note of the sap itself. They speculated that it might be similar to the protein or carbohydrate substances that other plants exude from little outgrowths called microhairs. While scientists don’t know exactly what the function of those substances might be, there are a bunch of hypotheses.

For example, they might keep the plant from drying out, defend the plant from pathogens, or they might wash into the soil to inhibit the growth of surrounding plants. Either way, we’ll just gonna have to stick to good old acetic acid and sodium chloride acetate for our salt and vinegar snacks for now. Frogs and snakes are well known for having poisonous mucus membranes… but birds?

Not so much. The hooded pitohui is native to New Guinea and is brightly colored, which maybe should have been a warning… but like, really, no one expected a bird to be poisonous. So, the story goes like this: A grad student — it’s always grad students — was studying birds of paradise in the 1990s in New Guinea.

And pituhois often got caught in his net. The student got a few cuts while trying to untangle one of these birds, and when he licked the wounds, he found that his mouth started to tingle, burn, and go numb. Initially, he didn’t think much of it, but then another researcher had a similar experience.

So the grad student caught a pituhoi, plucked one of its feathers, and just put it in his mouth. And yes, same burning sensation. He and other researchers later analyzed the birds’ skin and feathers and discovered that these pituhois weren’t messing around when it came to scaring off their predators.

They had the same kind of poison as the infamous Colombian poison-dart frogs. It’s called homobatrachotoxin, and it packs a punch. The researchers who licked it seem to have been OK, but it’s one of the most lethal poisons out there, and it works by permanently binding to the sodium receptors on your neurons.

That stops the neurons from firing and means that they no longer send signals to your muscles. Then, the muscles go into paralysis… including some pretty important ones, like your heart muscles and lungs. Also, there’s no antidote.

Native New Guineans called the hooded pituhoi a “rubbish bird,” because it’s no good for eating, so maybe that should have been a hint, but somehow doesn’t seem like a strong enough term? Anyway, the question then was where the birds get this poison from and how they evolved to have the same toxin as a frog on the other side of the world. In 2004, the same researcher finally figured it out.

The birds were actually borrowing homobatrachotoxin from someone else: the beetles they ate. He speculated that the frogs could also be eating the same beetle, which would explain why they produce the same toxin despite being continents apart. But where the beetles get the poison and how the pituhois — and the frogs — evolved to be able to eat and use it without dying are still unknown.

These days, most of us know not to lick the science. Poisoning yourself can really ruin your day also, kill you. But back in the day?

A lot of chemists and pharmacists tasted all their stuff, much like any good cook might taste their tomato sauce to make sure they added enough salt. Carl Wilhelm Scheele was one of those lick-happy chemists who lived in Europe in the 1700s. He’s widely credited with discovering at least seven elements — although other researchers often got credit for them, because he wasn’t super into publicizing his work and had more interest in making sure his collaborators got credit.

Still, it’s argued that he at least discovered oxygen, barium, manganese, and tungsten. He also discovered a gas from which chlorine was later isolated, a number of organic acids, and a green copper-and-arsenic-based pigment that came to be called Scheele’s green… and that might have played a role in the death of Napoleon. He meticulously described the compounds he discovered, including their odor and, yep, their taste.

One of his more flavorful discoveries was tartaric acid, which is known for its sour taste and is today part of the stuff we call baking powder. But he also tasted more dangerous things like hydrogen cyanide, which he synthesized in 1782 from a pigment called Prussian blue. He described it as having a taste that bordered on sweet, and having a heating effect in his mouth.

Without his work, we might not know some of the properties of chemicals like this — but then again, that might have been okay. Because in case you were wondering, yes, hydrogen cyanide is that cyanide, and it’s super poisonous. Cyanide ions bind to receptors in your mitochondria, keeping your cells from using oxygen.

Which is, you know, bad. Scheele somehow, luckily, didn’t die from tasting his hydrogen cyanide. It was far from the only toxic substance he tasted, though, and it’s widely suspected that all of this self-administered poison caught up with him.

He died in his 40s from symptoms that some sources describe as being similar to chronic mercury or arsenic poisoning. There’s no denying he was a super productive chemist and discovered a ton of useful things. But licking stuff probably wasn’t the best way to sustainably long term do chemistry.

Having just told you not to lick the science, there’s actually a whole field of researchers who lick stuff on the regular: geologists! That sounds weird, but what’s known as the “lick test” is actually the best way to tell a fossil from a rock, because the tongue sticks slightly to the porous structure of the fossil. A quick tap with the tip of the tongue is also a good way to distinguish between minerals like halite and sylvite, which can look alike but tasty salty and sour, respectively.

But tasting things can lead to other discoveries, too. Like, in a paper published in 2013, a geologist described how she used the lick test to identify really, really old water, including one sample that was up to 2.6 billion years old. Deep underground, in mines in Canada, she and her team found pockets of water that had been hidden in ancient bedrock for billions of years.

Ancient water is way saltier than seawater because of ongoing reactions between the water and the rock it’s tucked away in. Which means that tasting it can be an easy way to tell it apart from the run-of-the-mill. H2O we encounter every day.

Further tests are necessary to precisely pinpoint water’s age, of course. But especially underground and in the dark, picking out which pocket of liquid is saltiest is a quick and dirty way to decide what to take back and test. What’s really cool about this water, though, is that it can give us a sense of what Earth’s environment was like when life was first developing.

Its composition is similar to the mixture that scientists have long hypothesized might have allowed amino acids to develop. And the reactions between the rock and the water that make it salty might also have provided the energy necessary for life. The water they found in Canada didn’t have any organisms in it, but the researchers argue that it definitely could have supported them.

Also, pockets of water they found in a mine in South Africa, which were tens of millions of years old, did have colonies of microorganisms in them. The microbes were living off of dissolved hydrogen… in the dark… 2.8 kilometers underground. Which is completely bonkers.

So licking stuff? It sounds silly, but it totally can be a legit, serious science tool. I mean, in a majority of cases, it’s really not worth being poisoned.

So like please don’t try this at home. But it turns out that taste can tell us a lot, just like all our other senses. And it has led us to some weird, awesome discoveries that we might not have arrived at otherwise.

Thanks for watching this episode of SciShow! If you want to learn more about accidental discoveries like those artificial sweeteners, you can watch our episode about six accidental discoveries you probably haven’t heard of yet. [ ♪OUTRO ].