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Speaker 1: Welcome to brain Stuff, a production of iHeartRadio. Hey brain stuff,

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Speaker 1: Lauren Bollebam here it's not. It is inherently gross. We

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Speaker 1: swallow loads of it every day, even on our healthiest

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Speaker 1: of days. And that slimy, gelatinous goo we call mucus

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Speaker 1: isn't just in our noses. It's actually found on all

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Speaker 1: of the wet surfaces of your body that aren't covered

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

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Speaker 1: and eyes, just to name a few. So why do

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Speaker 1: we have to put up with it? It turns out

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Speaker 1: that mucus plays a hugely important role in keeping us healthy,

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Speaker 1: and not just us humans, similar mucus helps protect pretty

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Speaker 1: much all other creatures as well. But mucus is a

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Speaker 1: bit of a mystery. Okay. We know that mucus is

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Speaker 1: made up almost entirely of water, along with tiny amounts

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

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Speaker 1: And we know that mammals, fish, amphibians, reptiles, birds, molluscs,

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Speaker 1: and some other invertebrates all produce mucus. But a study

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Speaker 1: from twenty twenty two found that many mucus related genes

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Speaker 1: don't share a common ancestor. This is relatively unusual because

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Speaker 1: genes with a similar function often evolve from a common

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Speaker 1: ancestral gene. But just in humans, genes that encode for

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Speaker 1: mucus are members of several families that probably evolved independently.

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Speaker 1: Further study, a team from the University of Buffalo looked

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Speaker 1: at the saliva of forty nine different species of mammals. Specifically,

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Speaker 1: they were looking at the musins in that saliva, musins

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Speaker 1: being the sort of key ingredient in mucus that makes

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Speaker 1: it slimy because musins tend to be good at forming

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Speaker 1: gels with water, and the research found that in some mammals,

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Speaker 1: new types of musins had evolved from other kinds of

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Speaker 1: non musin proteins, like fifteen independent times. The lead author

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Speaker 1: of the study, a University of Buffalo PhD student by

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Speaker 1: the name of Peter Pietz, said in a press release,

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

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Speaker 1: over again in different species at different times, it suggests

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

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Speaker 1: it beneficial. So it seems that evolution loves making slime certainly.

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Speaker 1: Mucus serves our bodies in lots of different ways, including

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Speaker 1: preventing tissues from drying out and cracking, which would expose

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Speaker 1: them to infection, lubricating the eyes, protecting the stomach lining

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Speaker 1: from acid, removing or trapping foreign substances, thus preventing them

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Speaker 1: from getting into the lungs or the bloodstream, and keeping

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Speaker 1: the bodies trillions of friendly bacterial inhabitants under control. Our

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Speaker 1: bodies are constantly producing mucus. In fact, the respiratory system

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Speaker 1: alone cranks out more than a liter of it every day,

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Speaker 1: and that's about forty fluid ounces. A lot of it

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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 the 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 unless you happen

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Speaker 1: to speak into microphones for a living. And thank you,

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Speaker 1: by the way, to Tyler and all of the other

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Speaker 1: fabulous producers here at iHeart for editing out my many,

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Speaker 1: many many throat clears in every episode. Anyway, when you're sick,

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Speaker 1: your mucus becomes thicker and stickier as your body ramps

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Speaker 1: up production of it in an attempt to flush out

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Speaker 1: the offending pathogens. And as we said above, humans aren't

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Speaker 1: the only creatures to produce mucus. Other animals do some

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Speaker 1: amazing things with it. Snails and slugs eat visco elastic

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Speaker 1: mucus that acts as both an adhesive and a lubricant,

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Speaker 1: enabling them to scoop seemingly effortlessly over rough terrain and

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Speaker 1: move vertically up it. All fish are covered in mucus,

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Speaker 1: but parrotfish also spit out little mucus sleeping bags that

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Speaker 1: they encase themselves in every night to protect them from parasites.

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Speaker 1: Some sea sponges sneeze to clear debris out of their pores,

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Speaker 1: similar to how you might blow your nose, but it

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Speaker 1: takes them between twenty and fifty minutes to complete one

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Speaker 1: sneeze like contraction and cave dwelling birds called swiftlets, use

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

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Speaker 1: cave walls. The nests are a delicacy in some Chinese cuisines,

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Speaker 1: in which the delicate cup shaped nests, which look a

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Speaker 1: little bit like a pastry shell when they're dried, are

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Speaker 1: boiled down to form a gelatinous soup called appropriately Birds'

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Speaker 1: Nest Soup. A snot still has a lot to teach us.

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Speaker 1: At the Massachusetts Institute of Technology, there's a lab run

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Speaker 1: by biological engineering professor Katharina Ribbeck that's dedicated to learning

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Speaker 1: how some pathogenic microbes have evolved to slip in through

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Speaker 1: our mucus barriers. Aribic told Statnews back in twenty eighteen

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Speaker 1: that mucus is the unsown hero that has been taming

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Speaker 1: problematic pathogens for millions of years. She and her team

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Speaker 1: want to figure out how to harness mucus to prevent

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Speaker 1: more 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 snot on how stuffworks

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Speaker 1: dot com, written by Jennifer Walker Journey Brainstuff is production

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Speaker 1: of by Heart Radio in partnership with how Stuffworks dot

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Speaker 1: Com and is produced by Tyler Klaying. For more podcasts

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Speaker 1: my heart Radio, visit the iHeartRadio app, Apple Podcasts, or

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Speaker 1: wherever you listen to your favorite shows.