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Speaker 1: Welcome to brain Stuff, a production of iHeart Radio. Hey

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Speaker 1: brain Stuff, Lauren vogel Bomb here. It's not it's not

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Speaker 1: the most appetizing subject. It might unsettle you to know

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Speaker 1: that you swallow loads of it every day, even on

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Speaker 1: your healthiest of days. And that's limy gelatinous goo we

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Speaker 1: call mucus doesn't just roll down the back of your

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Speaker 1: throat or clog up your nose. It's actually found on

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Speaker 1: all of the wet surfaces of your body not covered

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Speaker 1: by skin. That includes the lungs, sinuses, mouth, stomach, intestines,

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Speaker 1: genital tissue, and I sockets, just to name a few.

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Speaker 1: So why do we have to put up with it?

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Speaker 1: It's because, as disgusting as it may be, mucus plays

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Speaker 1: a hugely important role in keeping us healthy, and not

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Speaker 1: just as humans. The same mucus helps protect other creatures too.

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

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Speaker 1: and even some invertebrates produce mucus, a new study has

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Speaker 1: found that many mucus genes don't share a common ancestor.

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Speaker 1: This is unusual because genes with a similar function often

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Speaker 1: evolved from a common ancestral gene, but in humans, for instance,

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Speaker 1: genes that encode for mucus are members of several families

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Speaker 1: that probably evolved independently. The key component that makes mucus

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Speaker 1: slimy is a set of proteins called mucins. In this

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Speaker 1: new study, published in August two in the journal Science Advances,

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Speaker 1: a team from the University of Buffalo looked into the

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Speaker 1: musins and saliva across forty nine different mammal species, and

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Speaker 1: they discovered that some non musan proteins in some mammals

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Speaker 1: had evolved into musans. The researchers set in a press release,

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Speaker 1: if these musins keep evolving from non musans over and

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Speaker 1: over again in different species at different times, it's just

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Speaker 1: that there is some sort of adaptive pressure that makes

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Speaker 1: it beneficial. And then at the other end of the spectrum,

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Speaker 1: and maybe if this mechanism goes off the rails happening

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Speaker 1: too much or in the wrong tissue, then maybe it

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Speaker 1: can lead to disease like certain cancers or mucosal illnesses.

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

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Speaker 1: and where does it come from? A mucus is made

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Speaker 1: up almost entirely of water, but is spiked with small

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Speaker 1: amounts of hundreds of compounds, including fats, salts, and proteins

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Speaker 1: such as slim ifying mucins. Mucus serves our bodies in

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Speaker 1: different ways, by preventing tissues from drying out and cracking,

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Speaker 1: which could expose them to infection, by lubricating the eyes,

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Speaker 1: by protecting the stomach lining from acid, by removing or

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Speaker 1: trapping substances and thus preventing them from getting into the

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Speaker 1: lungs where bloodstream, and by keeping the bodies trillions of

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Speaker 1: bacterial inhabitants under control. Our bodies are constantly producing mucus.

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Speaker 1: The respiratory system alone cranks out more than a leader

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Speaker 1: or court of it every day. A lot of that

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Speaker 1: slides down the back of your throat, into your stomach

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Speaker 1: and eventually makes its way out of your body. When

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Speaker 1: you're healthy, you're probably not aware of all the mucus

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Speaker 1: rolling down the back of your throat at all. But

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Speaker 1: when you're sick, your mucus becomes thicker and stickier as

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Speaker 1: your body ramps up production of it to quickly flush

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

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Speaker 1: the only creatures that produce mucus, and those other critters

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Speaker 1: do some amazing things with it. For example, the visco

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Speaker 1: elastic mucus that snails and slugs excrete acts as both

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Speaker 1: an adhesive and a lubricant, enabling them to scoot seemingly

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Speaker 1: effortlessly over rough terrain. All fish are covered in mucus,

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Speaker 1: but parrot fish also puke out little mucus sleeping bags

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Speaker 1: that they encase themselves in every night to protect them

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Speaker 1: from parasites. In sea lions, mucus keeps the eyes and

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Speaker 1: nasal tissues moist, and they're said to launch snot rockets,

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Speaker 1: across great distances. Female cave dwelling birds called swiftlets use

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Speaker 1: their saliva to build gooey nests to stick to steep

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Speaker 1: cave walls. The nests are delicacy in China and are

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Speaker 1: boiled down without eggs to form a gelatinous soup called

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Speaker 1: bird's nest soup. And mucus might do even more for

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Speaker 1: us in the future. Back in a biological engineering professor

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Speaker 1: at the Massachusetts Institute of Technology told stat News that

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Speaker 1: mucus was the unsung hero that had been taming problematic

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Speaker 1: pathogens for millions of years. The team at m I

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Speaker 1: T wants to figure out how to harness mucus to

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Speaker 1: prevent infections, especially those caused by bacteria that are resistant

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Speaker 1: to antibiotics. Today's episode is based on the article The

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Speaker 1: Science Behind Why We All Have Stopped on How Stuff

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Speaker 1: Work stuck Um, written by Jennifer Walker. Journey Brainstuff is

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Speaker 1: production of by Heart Radio in partnership with how stuff

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

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Speaker 1: more podcasts my heart Radio, visit the heart Radio app,

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Speaker 1: Apple Podcasts, or wherever you listen to your favorite shows