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What Does That Dangly Thing in the Back of Your Throat Do?

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Uvula image via Shutterstock

The uvula is one of the weirdest looking features of the human body. Yet despite its infamy, scientists have spent centuries puzzling over its function.

The hangy ball's full name is the “palatine uvula,” referring to its location on your soft palate. Not to be confused with the uvula vermis, a lobe of the cerebellum, or the uvula vesicae, in the urinary bladder. 

Through history, scientists have had many theories about the uvula. Among them:

That it once helped guide the flow of food and water, and, in humans, was a mere remnant from previous mammals who had to lean down to eat and drink.
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That it induces the gag reflex. And therefore isn’t the best place to get a piercing.
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That it contributed to “chronic cough.” A problem that 19th-century doctors treated with a “simple” “clipping” procedure.
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That it contributes to cardiovascular problems like sudden infant death syndrome (SIDS) and sleep apnea.

Even today, some doctors treat sleep apnea by having the uvula removed. Unpleasant as that sounds, much of the recent uvular research has come about by studying uvulopalatopharyngoplasty patients (uvula-less people). Several such studies have concluded that the uvula is really good at excreting saliva. A lot of saliva, in a really short amount of time. Another study compared the soft palates of eight different mammals, and found that a small, underdeveloped uvula was found in only two baboons.

Don’t Leave Us Hanging

So what does the dangly throat thing do? Because the uvula is basically unique to humans, scientists basically agree that it primarily serves as an accessory to speech. You know what it’s like to have your throat go dry before talking to a large group? The uvula is there to provide the proper lubrication for complicated human speech. In time, we’ll likely learn that the uvula does some other cool things to boot, but to quote one study on the subject, it “may be another marker of human evolution that differentiates man from other mammals.” For now, that’s pretty cool.

This post originally appeared in 2012.

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Geological Map Shows the Massive Reservoir Bubbling Beneath Old Faithful
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Yellowstone National Park is home to rivers, waterfalls, and hot springs, but Old Faithful is easily its most iconic landmark. Every 45 to 125 minutes, visitors gather around the geyser to watch it shoot streams of water reaching up to 100 feet in the air. The punctual show is one of nature’s greatest spectacles, but new research from scientists at the University of Utah suggests that what’s going on at the geyser’s surface is just the tip of the iceberg.

The study, published in the journal Geophysical Research Letters, features a map of the geological plumbing system beneath Old Faithful. Geologists have long known that the eruptions are caused by water heated by volcanic rocks beneath the ground reaching the boiling point and bubbling upwards through cracks in the earth. But the place where this water simmers between appearances has remained mysterious to scientists until now.

Using 133 seismometers scattered around Old Faithful and the surrounding area, the researchers were able to record the tiny tremors caused by pressure build-up in the hydrothermal reservoir. Two weeks of gathering data helped them determine just how large the well is. The team found that the web of cracks and fissures beneath Old Faithful is roughly 650 feet in diameter and capable of holding more than 79 million gallons of water. When the geyser erupts, it releases just 8000 gallons. You can get an idea of how the reservoir fits into the surrounding geology from the diagram below.

Geological map of geyser.
Sin-Mei Wu, University of Utah

After making the surprising discovery, the study authors plan to return to the area when park roads close for the winter to conduct further research. Next time, they hope to get even more detailed images of the volatile geology beneath this popular part of Yellowstone.

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Animals
Why Do Female Spotted Hyenas Give Birth Through Their Pseudo-Penises?
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At the zoo, you can sometimes tell the difference between male and female animals by noting their physical size, their behavior, and yes, their nether regions. Hyenas, however, flip the script: Not only are lady spotted hyenas bigger and meaner than their male counterparts, ruling the pack with an iron paw, they also sport what appear to be penises—shaft, scrotum, and all.

"Appear" is the key word here: These 7-inch-long phalluses don't produce sperm, so they're technically really long clitorises in disguise. But why do female hyenas have them? And do they actually have to (gulp) give birth through them? Wouldn't that hurt … a lot?

The short answers to these questions are, respectively, "We don't know," "Yes," and "OW." Longer answers can be found in this MinuteEarth video, which provides the full lowdown on hyena sex. Don't say we didn't warn you.

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