Why Do So Many Animals Have Snot?

Mucus is gross, but it does a lot of good in humans and the many other animals that produce it. Learn more in this episode of BrainStuff, based on this article: https://health.howstuffworks.com/human-body/systems/respiratory/mucus.htm

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Episode Transcript

Speaker 1 (00:01):
Welcome to brain Stuff, a production of iHeart Radio. Hey
brain Stuff, Lauren vogel Bomb here. It's not it's not
the most appetizing subject. It might unsettle you to know
that you swallow loads of it every day, even on
your healthiest of days. And that's limy gelatinous goo we

(00:23):
call mucus doesn't just roll down the back of your
throat or clog up your nose. It's actually found on
all of the wet surfaces of your body not covered
by skin. That includes the lungs, sinuses, mouth, stomach, intestines,
genital tissue, and I sockets, just to name a few.
So why do we have to put up with it?

(00:43):
It's because, as disgusting as it may be, mucus plays
a hugely important role in keeping us healthy, and not
just as humans. The same mucus helps protect other creatures too.
But mucus is a bit of a mystery. Although mammals, fish, amphibians, mollusks,
and even some invertebrates produce mucus, a new study has

(01:04):
found that many mucus genes don't share a common ancestor.
This is unusual because genes with a similar function often
evolved from a common ancestral gene, but in humans, for instance,
genes that encode for mucus are members of several families
that probably evolved independently. The key component that makes mucus

(01:26):
slimy is a set of proteins called mucins. In this
new study, published in August two in the journal Science Advances,
a team from the University of Buffalo looked into the
musins and saliva across forty nine different mammal species, and
they discovered that some non musan proteins in some mammals
had evolved into musans. The researchers set in a press release,

(01:50):
if these musins keep evolving from non musans over and
over again in different species at different times, it's just
that there is some sort of adaptive pressure that makes
it beneficial. And then at the other end of the spectrum,
and maybe if this mechanism goes off the rails happening
too much or in the wrong tissue, then maybe it
can lead to disease like certain cancers or mucosal illnesses.

(02:15):
But okay, let's back up a step. What is mucus
and where does it come from? A mucus is made
up almost entirely of water, but is spiked with small
amounts of hundreds of compounds, including fats, salts, and proteins
such as slim ifying mucins. Mucus serves our bodies in
different ways, by preventing tissues from drying out and cracking,

(02:37):
which could expose them to infection, by lubricating the eyes,
by protecting the stomach lining from acid, by removing or
trapping substances and thus preventing them from getting into the
lungs where bloodstream, and by keeping the bodies trillions of
bacterial inhabitants under control. Our bodies are constantly producing mucus.

(02:59):
The respiratory system alone cranks out more than a leader
or court of it every day. A lot of that
slides down the back of your throat, into your stomach
and eventually makes its way out of your body. When
you're healthy, you're probably not aware of all the mucus
rolling down the back of your throat at all. But
when you're sick, your mucus becomes thicker and stickier as

(03:20):
your body ramps up production of it to quickly flush
out any offending pathogens. And as we said, humans aren't
the only creatures that produce mucus, and those other critters
do some amazing things with it. For example, the visco
elastic mucus that snails and slugs excrete acts as both
an adhesive and a lubricant, enabling them to scoot seemingly

(03:43):
effortlessly over rough terrain. All fish are covered in mucus,
but parrot fish also puke out little mucus sleeping bags
that they encase themselves in every night to protect them
from parasites. In sea lions, mucus keeps the eyes and
nasal tissues moist, and they're said to launch snot rockets,

(04:04):
across great distances. Female cave dwelling birds called swiftlets use
their saliva to build gooey nests to stick to steep
cave walls. The nests are delicacy in China and are
boiled down without eggs to form a gelatinous soup called
bird's nest soup. And mucus might do even more for

(04:26):
us in the future. Back in a biological engineering professor
at the Massachusetts Institute of Technology told stat News that
mucus was the unsung hero that had been taming problematic
pathogens for millions of years. The team at m I
T wants to figure out how to harness mucus to
prevent infections, especially those caused by bacteria that are resistant

(04:48):
to antibiotics. Today's episode is based on the article The
Science Behind Why We All Have Stopped on How Stuff
Work stuck Um, written by Jennifer Walker. Journey Brainstuff is
production of by Heart Radio in partnership with how stuff
Works dot Com, and it's produced by Tyler Klang. Four
more podcasts my heart Radio, visit the heart Radio app,

(05:10):
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