1
00:00:07,149 --> 00:00:13,480
Charles Osborne began to hiccup
in 1922 after a hog fell on top of him.

2
00:00:13,480 --> 00:00:16,860
He wasn't cured until 68 years later

3
00:00:16,860 --> 00:00:20,930
and is now listed by Guinness as
the world record holder

4
00:00:20,930 --> 00:00:23,001
for hiccup longevity.

5
00:00:23,001 --> 00:00:25,641
Meanwhile, Florida teen Jennifer Mee

6
00:00:25,641 --> 00:00:28,951
may hold the record 
for the most frequent hiccups,

7
00:00:28,951 --> 00:00:34,381
50 times per minute 
for more than four weeks in 2007.

8
00:00:34,381 --> 00:00:37,601
So what causes hiccups?

9
00:00:37,601 --> 00:00:41,871
Doctors point out that a round
of hiccups often follows from stimuli

10
00:00:41,871 --> 00:00:43,781
that stretch the stomach,

11
00:00:43,781 --> 00:00:45,052
like swallowing air

12
00:00:45,052 --> 00:00:48,176
or too rapid eating or drinking.

13
00:00:48,176 --> 00:00:51,616
Others associate hiccups 
with intense emotions

14
00:00:51,616 --> 00:00:53,442
or a response to them:

15
00:00:53,442 --> 00:00:54,172
laughing,

16
00:00:54,172 --> 00:00:54,900
sobbing,

17
00:00:54,900 --> 00:00:55,846
anxiety,

18
00:00:55,846 --> 00:00:57,641
and excitement.

19
00:00:57,641 --> 00:01:00,324
Let's look at what happens when we hiccup.

20
00:01:00,324 --> 00:01:05,623
It begins with an involuntary spasm
or sudden contraction of the diaphragm,

21
00:01:05,623 --> 00:01:08,142
the large dome-shaped muscle
below our lungs

22
00:01:08,142 --> 00:01:10,611
that we use to inhale air.

23
00:01:10,611 --> 00:01:15,361
This is followed almost immediately
by the sudden closure of the vocal chords

24
00:01:15,361 --> 00:01:17,032
and the opening between them,

25
00:01:17,032 --> 00:01:19,082
which is called the glottis.

26
00:01:19,082 --> 00:01:23,263
The movement of the diaphragm
initiates a sudden intake of air,

27
00:01:23,263 --> 00:01:27,250
but the closure of the vocal chords
stops it from entering the wind pipe

28
00:01:27,250 --> 00:01:28,922
and reaching the lungs.

29
00:01:28,922 --> 00:01:32,692
It also creates the characteristic sound:
"hic."

30
00:01:32,692 --> 00:01:36,603
To date, there is no known function
for hiccups.

31
00:01:36,603 --> 00:01:40,652
They don't seem to provide any medical
or physiological advantage.

32
00:01:40,652 --> 00:01:46,972
Why begin to inhale air only to suddenly
stop it from actually entering the lungs?

33
00:01:46,972 --> 00:01:48,279
Anatomical structures,

34
00:01:48,279 --> 00:01:51,712
or physiological mechanisms, 
with no apparent purpose

35
00:01:51,712 --> 00:01:54,874
present challenges 
to evolutionary biologists.

36
00:01:54,874 --> 00:01:59,493
Do such structures serve some hidden
function that hasn't yet been discovered?

37
00:01:59,493 --> 00:02:02,454
Or are they relics 
of our evolutionary past,

38
00:02:02,454 --> 00:02:04,523
having once served some important purpose

39
00:02:04,523 --> 00:02:09,517
only to persist into the present 
as vestigial remnants?

40
00:02:09,517 --> 00:02:11,285
One idea is that hiccups began

41
00:02:11,285 --> 00:02:14,803
many millions of years
before the appearance of humans.

42
00:02:14,803 --> 00:02:19,155
The lung is thought to have evolved
as a structure to allow early fish,

43
00:02:19,155 --> 00:02:23,394
many of which lived in warm, stagnant
water with little oxygen,

44
00:02:23,394 --> 00:02:28,144
to take advantage of the abundant oxygen
in the air overhead.

45
00:02:28,144 --> 00:02:31,414
When descendants of these animals
later moved onto land,

46
00:02:31,414 --> 00:02:36,574
they moved from gill-based ventilation
to air-breathing with lungs.

47
00:02:36,574 --> 00:02:41,814
That's similar to the much more rapid
changes faced by frogs today

48
00:02:41,814 --> 00:02:44,198
as they transition 
from tadpoles with gills

49
00:02:44,198 --> 00:02:46,425
to adults with lungs.

50
00:02:46,425 --> 00:02:51,414
This hypothesis suggests that the hiccup
is a relic of the ancient transition

51
00:02:51,414 --> 00:02:53,996
from water to land.

52
00:02:53,996 --> 00:02:56,975
An inhalation that could 
move water over gills

53
00:02:56,975 --> 00:03:02,507
followed by a rapid closure of the glottis
preventing water from entering the lungs.

54
00:03:02,507 --> 00:03:03,857
That's supported by evidence

55
00:03:03,857 --> 00:03:08,284
which suggests that the neural patterning
involved in generating a hiccup

56
00:03:08,284 --> 00:03:13,996
is almost identical to that responsible
for respiration in amphibians.

57
00:03:13,996 --> 00:03:18,187
Another group of scientists believe
that the reflex is retained in us today

58
00:03:18,187 --> 00:03:21,705
because it actually provides
an important advantage.

59
00:03:21,705 --> 00:03:25,325
They point out that true hiccups
are found only in mammals

60
00:03:25,325 --> 00:03:28,826
and that they're not retained in birds,
lizards, turtles,

61
00:03:28,826 --> 00:03:32,835
or any other exclusively 
air-breathing animals.

62
00:03:32,835 --> 00:03:38,033
Further, hiccups appear in human babies
long before birth

63
00:03:38,033 --> 00:03:41,457
and are far more common in infants
that adults.

64
00:03:41,457 --> 00:03:43,187
Their explanation for this

65
00:03:43,187 --> 00:03:47,447
involves the uniquely mammalian 
activity of nursing.

66
00:03:47,447 --> 00:03:50,737
The ancient hiccup reflex may have been
adapted by mammals

67
00:03:50,737 --> 00:03:55,761
to help remove air from the stomach
as a sort of glorified burp.

68
00:03:55,761 --> 00:03:59,607
The sudden expansion of the diaphragm
would raise air from the stomach,

69
00:03:59,607 --> 00:04:04,858
while a closure of the glottis would
prevent milk from entering the lungs.

70
00:04:04,858 --> 00:04:08,287
Sometimes, a bout of hiccups will go
on and on,

71
00:04:08,287 --> 00:04:10,677
and we try home remedies:

72
00:04:10,677 --> 00:04:13,538
sipping continuously 
from a glass of cold water,

73
00:04:13,538 --> 00:04:15,009
holding one's breath,

74
00:04:15,009 --> 00:04:17,238
a mouthful of honey or peanut butter,

75
00:04:17,238 --> 00:04:19,228
breathing into a paper bag,

76
00:04:19,228 --> 00:04:21,709
or being suddenly frightened.

77
00:04:21,709 --> 00:04:26,229
Unfortunately, scientists have yet
to verify that any one cure

78
00:04:26,229 --> 00:04:29,097
works better or more consistently
than others.

79
00:04:29,097 --> 00:04:33,409
However, we do know one thing
that definitely doesn't work.