0:00:07.149,0:00:13.480
Charles Osborne began to hiccup[br]in 1922 after a hog fell on top of him.

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He wasn't cured until 68 years later

0:00:16.860,0:00:20.930
and is now listed by Guinness as[br]the world record holder

0:00:20.930,0:00:23.001
for hiccup longevity.

0:00:23.001,0:00:25.641
Meanwhile, Florida teen Jennifer Mee

0:00:25.641,0:00:28.951
may hold the record [br]for the most frequent hiccups,

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50 times per minute [br]for more than four weeks in 2007.

0:00:34.381,0:00:37.601
So what causes hiccups?

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Doctors point out that a round[br]of hiccups often follows from stimuli

0:00:41.871,0:00:43.781
that stretch the stomach,

0:00:43.781,0:00:45.052
like swallowing air

0:00:45.052,0:00:48.176
or too rapid eating or drinking.

0:00:48.176,0:00:51.616
Others associate hiccups [br]with intense emotions

0:00:51.616,0:00:53.442
or a response to them:

0:00:53.442,0:00:54.172
laughing,

0:00:54.172,0:00:54.900
sobbing,

0:00:54.900,0:00:55.846
anxiety,

0:00:55.846,0:00:57.641
and excitement.

0:00:57.641,0:01:00.324
Let's look at what happens when we hiccup.

0:01:00.324,0:01:05.623
It begins with an involuntary spasm[br]or sudden contraction of the diaphragm,

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the large dome-shaped muscle[br]below our lungs

0:01:08.142,0:01:10.611
that we use to inhale air.

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This is followed almost immediately[br]by the sudden closure of the vocal chords

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and the opening between them,

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which is called the glottis.

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The movement of the diaphragm[br]initiates a sudden intake of air,

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but the closure of the vocal chords[br]stops it from entering the wind pipe

0:01:27.250,0:01:28.922
and reaching the lungs.

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It also creates the characteristic sound:[br]"hic."

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To date, there is no known function[br]for hiccups.

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They don't seem to provide any medical[br]or physiological advantage.

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Why begin to inhale air only to suddenly[br]stop it from actually entering the lungs?

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Anatomical structures,

0:01:48.279,0:01:51.712
or physiological mechanisms, [br]with no apparent purpose

0:01:51.712,0:01:54.874
present challenges [br]to evolutionary biologists.

0:01:54.874,0:01:59.493
Do such structures serve some hidden[br]function that hasn't yet been discovered?

0:01:59.493,0:02:02.454
Or are they relics [br]of our evolutionary past,

0:02:02.454,0:02:04.523
having once served some important purpose

0:02:04.523,0:02:09.517
only to persist into the present [br]as vestigial remnants?

0:02:09.517,0:02:11.285
One idea is that hiccups began

0:02:11.285,0:02:14.803
many millions of years[br]before the appearance of humans.

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The lung is thought to have evolved[br]as a structure to allow early fish,

0:02:19.155,0:02:23.394
many of which lived in warm, stagnant[br]water with little oxygen,

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to take advantage of the abundant oxygen[br]in the air overhead.

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When descendants of these animals[br]later moved onto land,

0:02:31.414,0:02:36.574
they moved from gill-based ventilation[br]to air-breathing with lungs.

0:02:36.574,0:02:41.814
That's similar to the much more rapid[br]changes faced by frogs today

0:02:41.814,0:02:44.198
as they transition [br]from tadpoles with gills

0:02:44.198,0:02:46.425
to adults with lungs.

0:02:46.425,0:02:51.414
This hypothesis suggests that the hiccup[br]is a relic of the ancient transition

0:02:51.414,0:02:53.996
from water to land.

0:02:53.996,0:02:56.975
An inhalation that could [br]move water over gills

0:02:56.975,0:03:02.507
followed by a rapid closure of the glottis[br]preventing water from entering the lungs.

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That's supported by evidence

0:03:03.857,0:03:08.284
which suggests that the neural patterning[br]involved in generating a hiccup

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is almost identical to that responsible[br]for respiration in amphibians.

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Another group of scientists believe[br]that the reflex is retained in us today

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because it actually provides[br]an important advantage.

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They point out that true hiccups[br]are found only in mammals

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and that they're not retained in birds,[br]lizards, turtles,

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or any other exclusively [br]air-breathing animals.

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Further, hiccups appear in human babies[br]long before birth

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and are far more common in infants[br]that adults.

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Their explanation for this

0:03:43.187,0:03:47.447
involves the uniquely mammalian [br]activity of nursing.

0:03:47.447,0:03:50.737
The ancient hiccup reflex may have been[br]adapted by mammals

0:03:50.737,0:03:55.761
to help remove air from the stomach[br]as a sort of glorified burp.

0:03:55.761,0:03:59.607
The sudden expansion of the diaphragm[br]would raise air from the stomach,

0:03:59.607,0:04:04.858
while a closure of the glottis would[br]prevent milk from entering the lungs.

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Sometimes, a bout of hiccups will go[br]on and on,

0:04:08.287,0:04:10.677
and we try home remedies:

0:04:10.677,0:04:13.538
sipping continuously [br]from a glass of cold water,

0:04:13.538,0:04:15.009
holding one's breath,

0:04:15.009,0:04:17.238
a mouthful of honey or peanut butter,

0:04:17.238,0:04:19.228
breathing into a paper bag,

0:04:19.228,0:04:21.709
or being suddenly frightened.

0:04:21.709,0:04:26.229
Unfortunately, scientists have yet[br]to verify that any one cure

0:04:26.229,0:04:29.097
works better or more consistently[br]than others.

0:04:29.097,0:04:33.409
However, we do know one thing[br]that definitely doesn't work.