WEBVTT - Why Do So Many Animals Have Snot?

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<v Speaker 1>Welcome to brain Stuff, a production of iHeart Radio. Hey

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<v Speaker 1>brain Stuff, Lauren vogel Bomb here. It's not it's not

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<v Speaker 1>the most appetizing subject. It might unsettle you to know

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<v Speaker 1>that you swallow loads of it every day, even on

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<v Speaker 1>your healthiest of days. And that's limy gelatinous goo we

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<v Speaker 1>call mucus doesn't just roll down the back of your

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<v Speaker 1>throat or clog up your nose. It's actually found on

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<v Speaker 1>all of the wet surfaces of your body not covered

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<v Speaker 1>by skin. That includes the lungs, sinuses, mouth, stomach, intestines,

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<v Speaker 1>genital tissue, and I sockets, just to name a few.

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<v Speaker 1>So why do we have to put up with it?

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<v Speaker 1>It's because, as disgusting as it may be, mucus plays

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<v Speaker 1>a hugely important role in keeping us healthy, and not

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<v Speaker 1>just as humans. The same mucus helps protect other creatures too.

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<v Speaker 1>But mucus is a bit of a mystery. Although mammals, fish, amphibians, mollusks,

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<v Speaker 1>and even some invertebrates produce mucus, a new study has

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<v Speaker 1>found that many mucus genes don't share a common ancestor.

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<v Speaker 1>This is unusual because genes with a similar function often

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<v Speaker 1>evolved from a common ancestral gene, but in humans, for instance,

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<v Speaker 1>genes that encode for mucus are members of several families

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<v Speaker 1>that probably evolved independently. The key component that makes mucus

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<v Speaker 1>slimy is a set of proteins called mucins. In this

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<v Speaker 1>new study, published in August two in the journal Science Advances,

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<v Speaker 1>a team from the University of Buffalo looked into the

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<v Speaker 1>musins and saliva across forty nine different mammal species, and

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<v Speaker 1>they discovered that some non musan proteins in some mammals

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<v Speaker 1>had evolved into musans. The researchers set in a press release,

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<v Speaker 1>if these musins keep evolving from non musans over and

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<v Speaker 1>over again in different species at different times, it's just

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<v Speaker 1>that there is some sort of adaptive pressure that makes

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<v Speaker 1>it beneficial. And then at the other end of the spectrum,

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<v Speaker 1>and maybe if this mechanism goes off the rails happening

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<v Speaker 1>too much or in the wrong tissue, then maybe it

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<v Speaker 1>can lead to disease like certain cancers or mucosal illnesses.

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<v Speaker 1>But okay, let's back up a step. What is mucus

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<v Speaker 1>and where does it come from? A mucus is made

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<v Speaker 1>up almost entirely of water, but is spiked with small

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<v Speaker 1>amounts of hundreds of compounds, including fats, salts, and proteins

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<v Speaker 1>such as slim ifying mucins. Mucus serves our bodies in

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<v Speaker 1>different ways, by preventing tissues from drying out and cracking,

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<v Speaker 1>which could expose them to infection, by lubricating the eyes,

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<v Speaker 1>by protecting the stomach lining from acid, by removing or

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<v Speaker 1>trapping substances and thus preventing them from getting into the

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<v Speaker 1>lungs where bloodstream, and by keeping the bodies trillions of

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<v Speaker 1>bacterial inhabitants under control. Our bodies are constantly producing mucus.

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<v Speaker 1>The respiratory system alone cranks out more than a leader

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<v Speaker 1>or court of it every day. A lot of that

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<v Speaker 1>slides down the back of your throat, into your stomach

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<v Speaker 1>and eventually makes its way out of your body. When

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<v Speaker 1>you're healthy, you're probably not aware of all the mucus

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<v Speaker 1>rolling down the back of your throat at all. But

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<v Speaker 1>when you're sick, your mucus becomes thicker and stickier as

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<v Speaker 1>your body ramps up production of it to quickly flush

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<v Speaker 1>out any offending pathogens. And as we said, humans aren't

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<v Speaker 1>the only creatures that produce mucus, and those other critters

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<v Speaker 1>do some amazing things with it. For example, the visco

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<v Speaker 1>elastic mucus that snails and slugs excrete acts as both

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<v Speaker 1>an adhesive and a lubricant, enabling them to scoot seemingly

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<v Speaker 1>effortlessly over rough terrain. All fish are covered in mucus,

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<v Speaker 1>but parrot fish also puke out little mucus sleeping bags

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<v Speaker 1>that they encase themselves in every night to protect them

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<v Speaker 1>from parasites. In sea lions, mucus keeps the eyes and

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<v Speaker 1>nasal tissues moist, and they're said to launch snot rockets,

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<v Speaker 1>across great distances. Female cave dwelling birds called swiftlets use

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<v Speaker 1>their saliva to build gooey nests to stick to steep

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<v Speaker 1>cave walls. The nests are delicacy in China and are

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<v Speaker 1>boiled down without eggs to form a gelatinous soup called

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<v Speaker 1>bird's nest soup. And mucus might do even more for

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<v Speaker 1>us in the future. Back in a biological engineering professor

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<v Speaker 1>at the Massachusetts Institute of Technology told stat News that

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<v Speaker 1>mucus was the unsung hero that had been taming problematic

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<v Speaker 1>pathogens for millions of years. The team at m I

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<v Speaker 1>T wants to figure out how to harness mucus to

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<v Speaker 1>prevent infections, especially those caused by bacteria that are resistant

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<v Speaker 1>to antibiotics. Today's episode is based on the article The

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<v Speaker 1>Science Behind Why We All Have Stopped on How Stuff

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<v Speaker 1>Work stuck Um, written by Jennifer Walker. Journey Brainstuff is

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<v Speaker 1>production of by Heart Radio in partnership with how stuff

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<v Speaker 1>Works dot Com, and it's produced by Tyler Klang. Four

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