Why Is Your First Instinct After Hurting Your Finger to Put It in Your Mouth?

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iStock

If you close your fingers in a car door or slam your funny bone into a wall, you might find your first reaction is to suck on your fingers or rub your elbow. Not only is this an instinctive self-soothing behavior, it's a pretty effective technique for temporarily calming pain signals to the brain.

But how and why does it work? To understand, you need to know about the dominant theory of how pain is communicated in the body.

In the 17th century, French scientist and philosopher René Descartes proposed that there were specific pain receptors in the body that "rang a bell in the brain" when a stimulus interacted with the body, Lorne Mendell, a professor of neurobiology and behavior at Stony Brook University in New York, tells Mental Floss. However, no study has effectively been able to identify receptors anywhere in the body that only respond to painful stimuli.

"You can activate certain nerve fibers that can lead to pain, but under other circumstances, they don't," Mendell says. In other words, the same nerve fibers that carry pain signals also carry other sensations.

In 1965, two researchers at MIT, Patrick Wall and Ronald Melzack, proposed what they called the gate control theory of pain, which, for the most part, holds up to this day. Mendell, whose research focuses on the neurobiology of pain and who worked with both men on their pain studies, explains that their research showed that feeling pain is more about a balance of stimuli on the different types of nerve fibers.

"The idea was that certain fibers that increased the input were ones that opened the gate, and the ones that reduced the input closed the gate," Mendell says. "So you have this idea of a gate control sitting across the entrance of the spinal cord, and that could either be open and produce pain, or the gate could be shut and reduce pain."

The gate control theory was fleshed out in 1996 when neurophysiologist Edward Perl discovered that cells contain nociceptors, which are neurons that signal the presence of tissue-damaging stimuli or the existence of tissue damage.

Of the two main types of nerve fibers—large and small—the large fibers carry non-nociceptive information (no pain), while small fibers transmit nociceptive information (pain).

Mendell explains that in studies where electric stimulation is applied to nerves, as the current is raised, the first fibers to be stimulated are the largest ones. As the intensity of the stimulus increases, smaller and smaller fibers get recruited in. "When you do this in a patient at low intensity, the patient will recognize the stimulus, but it will not be painful," he says. "But when you increase the intensity of the stimulus, eventually you reach threshold where suddenly the patient will say, 'This is painful.'"

Thus, "the idea was that shutting the gate was something that the large fibers produced, and opening the gate was something that the small fibers produced."

Now back to your pain. When you suck on a jammed finger or rub a banged shin, you're stimulating the large fibers with "counter irritation," Mendell says. The effect is "a decrease in the message, or the magnitude of the barrage of signals being driven across the incoming fiber activation. You basically shut the gate. That is what reduces pain."

This concept has created "a big industry" around treating pain with mild electrical stimulation, Mendell says, with the goal of stimulating those large fibers in the hopes they will shut the gate on the pain signals from the small fibers.

While counter irritation may not help dull the pain of serious injury, it may come in handy the next time you experience a bad bruise or a stubbed toe.

Great White Sharks May Have Led to Megalodons' Extinction

iStock.com/cdascher
iStock.com/cdascher

The megalodon has been extinct for millions of years, but the huge prehistoric shark still fascinates people today. Reaching 50 feet long, it's thought to be the largest shark to ever stalk the ocean, but according to a new study, the predator may have been brought down by familiar creature: the great white shark.

As Smithsonian reports, the analysis, published in the journal PeerJ, finds that the megalodon may have vanished from seas much earlier that previously believed. Past research showed that the last megalodons died roughly 2.6 million years ago, a time when other marine life was dying off in large numbers, possibly due to a supernova blasting Earth with radiation at the end of the Pliocene epoch.

A team of paleontologists and geologists revisited the fossils that this conclusion was originally based on for their new study. They found that many of the megalodon remains had been mislabeled, marked with imprecise dates, or dated using old techniques. After reassessing the specimens, they concluded that the species had likely gone extinct at least 1 million years earlier than past research indicates.

If the megalodon vanished 3.6 million years ago rather than 2.6 million years ago, it wasn't the victim of supernova radiation. One known factor that could explain the loss of the 13 million-year-old apex predator at this time is the rise of a new competitor: the great white shark. This predator came on the scene around the same time as the megalodon's decline, and though a full-grown great white shark is less than half the size of a mature megalodon, the species still would have been a stressor. Adult great whites likely competed with juvenile megalodons, and with the megalodon's favorite prey—small whales—becoming scarce at this time, this may have been enough to wipe the megalodons from existence.

Even if great white sharks eventually beat megalodons for dominance in the oceans, the megalodon's status as one of the most fearsome predators of all time shouldn't be contested. The giant sharks had 7-inch teeth and a bite stronger than that of a T. rex.

[h/t Smithsonian]

From Squatty Potty to Squat-N-Go: The Best Toilet Stool for Every Bathroom

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iStock.com/eldemir

In 2015, Squatty Potty's bathroom stool plopped into the popular conscience with a viral commercial that featured a unicorn joyfully pooping out a conveyor belt's worth of ice cream. The video racked up more than 35.9 million views on YouTube and reportedly caused a 600 percent jump in sales. "The stool for better stools" was a hit.

Now, it's a hit with the medical community, too. New research out of Ohio State University finds that the toilet stool—which aims to relax the puborectalis muscle and straighten out the rectum, making it easier to poop—really does help people who strain to empty their bowels. The study, published in the Journal of Clinical Gastroenterology's March 2019 issue, only involved 52 people, but it's the first clinical research into the Squatty Potty, and the results were very positive—71 percent of participants said they experienced faster bowel movements after using the stool for a month. A full 90 percent said they experienced less straining than before.

Since the Squatty Potty debuted, the company has inspired plenty of copycats, as well as launching a number of other official Squatty Potty design iterations targeted at every type of user. Here are the best toilet stool options for every bathroom.

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1. If You're Hesitant to Commit: The Squatty Potty Original

At just $25, the original Squatty Potty is a great entry-level option that will allow you to try out the system without sinking a ton of money into it. (And it's a whole lot cheaper than an endless supply of Metamucil.) The white plastic isn't the most elevated decor option, but it's durable, easy to clean, and relatively unobtrusive. It's available in a 7-inch-tall version for standard toilets or a 9-inch-tall version for comfort-height porcelain thrones. If you're not sure how tall your toilet is, the company makes an adjustable height Squatty Potty that can be configured to fit anywhere.

Buy it on Amazon, from Squatty Potty's website for $25, or at these other retailers:

2. If Your Bathroom is Tiny: The Squatty Potty Curve

The original Squatty Potty can be a bit clunky, but a newer version offers all the health benefits without taking up as much space. The Curve has a thinner footprint so that it doesn't stick out quite so far from under your toilet, but still has just enough room for your feet. The 7-inch stool comes in white, pink, black, and gray.

Buy it for $25 on Squatty Potty's website.

3. If You Text on the Toilet: The Keeney Bathroom Stool

A white and blue Keeney toilet stool
Keeney, Amazon

Keeney's toilet stool offers a few unusual features. For one, it has a storage bin designed to keep your wet wipes close at hand. More importantly, it's designed to hold up more than just your feet—it has a smartphone/tablet holder, too. Though toilet stools are designed to make your bowel movements speedier, if you're the kind of person who likes to spend a lot of time on the can, you can also tuck your smartphone into the built-in groove in the stool designed to keep your screen at optimal viewing angles. Whether you're watching Netflix or looking at Tinder, it offers a hands-free option that you're not going to find on any brand-name Squatty Potty. Ergonomically, it's also got slightly angled footrests designed to put you in the optimal pooping position.

Buy it on Amazon for $21.

4. If You're Into Minimalist Design: The Squatty Potty Slim

Great bowel movements and great interior design don't have to be mutually exclusive. Squatty Potty's high-fashion option may be pricier, but it doesn't have the medical-device vibes of the original model, either. Designed for small, urban apartments, it's a bit bigger than the Curve but a lot more aesthetically pleasing. The teak finish is great if you're going for a Scandinavian minimalist vibe, while the acrylic glass Slim Ghost model has an artsy mid-century modern look.

Buy the Slim Teak or the Slim Ghost on Squatty Potty's website for $60 and $80, respectively, or on Amazon for $80 or $83.

5. If You Need to Go on the Go: Squat-N-Go Bamboo X Toilet Stool

While Squatty Potty does make a portable version of its bathroom stool (the cleverly named Porta-Squatty), the most convenient travel stool is made by a competitor. Squat-N-Go's foldable footstool comes in two different pieces for easy storage and portability. The two bamboo platforms essentially act as stilts, propping up your feet separately. They offer the most customizable fit, with 7-inch, 8-inch, and 9-inch heights and the ability to place each footstool anywhere around the toilet, at any angle. When you're done, they fold down to just an inch tall and can be stowed in the included travel bag.

Buy it on Amazon for $40 or at these other retailers:

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