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  • [♪ INTRO]

  • *hic*

  • Ah, hiccups.

  • We've all been there.

  • Usually, they're no big dealunless you're one

  • of the 4,000 Americans admitted to the hospital

  • every year for hiccups, or you're that Iowa farmer

  • who hiccuped for 68 years straight.

  • Still, even the occasional bout of hiccups can be annoying.

  • And as you hold your breath or gulp down water

  • to try to make them stop, you may wonder:

  • Why is this happening to me?

  • Wellscientists don't really know.

  • But teeny little baby hiccups might provide a clue.

  • Hiccups mainly involve the diaphragm

  • (that dome-shaped muscle below your lungs

  • that drives your breathing) and the glottis

  • (the opening between your vocal cords).

  • Basically, they occur when your diaphragm spasms,

  • causing you to rapidly inhale.

  • That forces your glottis to audibly slam shut.

  • And everyone experiences them at some point

  • they're one of the first things we do in the womb.

  • Fetuses begin hiccuping at just nine weeks old.

  • And they continue to hiccup a ton

  • (between 8 and 14 times per hour!)

  • until they're about 24 weeks old.

  • Then, things settle down somewhat.

  • Though, young babies still hiccup a bunch,

  • especially if they were delivered early.

  • For example, preterm newborns (those born before 37 weeks)

  • spend an average of 15 minutes a day hiccuping!

  • Which got scientists at University College London

  • thinking that there might be a developmental purpose

  • behind all this convulsing.

  • So for a study published in December 2019,

  • they outfitted 13 newborns with a cute cap of electrodes

  • and monitored their hiccups.

  • They found that every time a baby's diaphragm contracted,

  • it triggered two large brainwaves, then a third brainwave.

  • The third wave is the most interesting,

  • because it looks similar to the brainwave created when we hear a noise.

  • So, the researchers think the babies may be hearing thehic

  • and connecting it in their brains

  • with the sensation of their diaphragm contracting.

  • This may allow their brains to form neural circuits

  • which help them sense what's happening with their internal organs.

  • The fancy scientific term for this ability is interoception,

  • and it's how you know you're having trouble breathing,

  • or your stomach feels full, or your heart is beating fast.

  • Creating these nerve connections between

  • the brain and the diaphragm could also help them

  • learn to control their breathing.

  • The same scientists think something similar

  • happens when fetuses kick in the womb.

  • Basically, those kicks may help them create mental maps

  • of their bodies so they can sense where their legs are,

  • and, eventually, learn to make voluntary movements.

  • So why do adults hiccup if our brains

  • don't need to learn how to breathe anymore?

  • That's a good question.

  • It could simply be that we can't get rid

  • of this reflex after it's served its purpose.

  • But who knows?

  • There aren't a whole lot of studies of run-of-the mill

  • occasional hiccuping in adults since, well,

  • it's not really something doctors are concerned about.

  • So maybe if scientists investigated hiccups more,

  • they'd find these spasms have a weirdly

  • amazing purpose in adults, too.

  • Thanks for asking about hiccups, Michelle and Anne!

  • And thanks in general to all of our patrons on Patreon.

  • We have the most wonderfully nerdy community of supporters!

  • If you'd like to join them, you can learn more at Patreon.com/SciShow.

  • And if you're already a patron and have a weird question

  • like this about how the world works, drop it in our QQ inbox!

  • We not only read those questions,

  • we make some of them into videos like this one.

  • So your question could be next!

  • [♪ OUTRO]

[♪ INTRO]

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