There is was awesome paper[1] on yawning in American Scientist a
while ago. It posits that the yawn is "primal, unstoppable and
contagious, revealing the evolutionary and neural basis of empathy
and unconscious behavior". The paper is only available to American
Scientist subscribers (well worth the $$), but here are some facts I
remember from it: 1) even fish yawn; yawning goes way back into our
evolutionary pasts 2) the inter yawn interval is 68 seconds (i've
timed my yawns a few times - 68 seconds is a spookily accurate
measure), 3) spontaneous yawning is performed by fetuses in the womb,
but kids don't learn contagious yawns until several years after birth.
[1] http://www.americanscientist.org/template/AssetDetail/assetid/47361
On Jul 3, 2007, at 11:42 PM, Udhay Shankar N wrote:
http://www.newscientist.com/article/mg19426104.400-yawning-may-
boost-brains-alertness.html
"
Yawning may boost brain's alertness
* 02 July 2007
* NewScientist.com news service
* Rowan Hooper
Yawning is not something we usually aim to provoke among our
readers, but have a yawn now. Does your brain feel cooler? Do you
feel more attentive? According to psychologists Andrew Gallup and
Gordon Gallup of the State University of New York at Albany, that
is why we yawn: to boost blood flow and chill the brain.
Not only that, brain-cooling explains why you can "catch" a yawn,
says Gordon Gallup. "We think contagious yawning is triggered by
empathic mechanisms which function to maintain group vigilance." In
other words, yawn-catching evolved to help raise the attentiveness
of the whole group.
The pair recruited 44 college students to watch, individually,
films of people yawning and recorded the number of contagious yawns
each volunteer made. Students were told to inhale and exhale in one
of four ways: strictly orally; strictly nasally; orally while
wearing a nose plug; or just breathe normally.
Fifty per cent of people told to breathe normally or through their
mouths yawned while watching other people yawn, while none of those
told to breathe through their noses yawned. The researchers also
found that subjects who held a cold pack to their forehead did not
catch yawns from the film, while those who held a warm or room-
temperature pack yawned normally (Evolutionary Psychology, vol 5, p
92).
"Subjects who held a cold pack to their forehead did not catch
yawns, while those who held a warm pack yawned normally"
Blood vessels in the nasal cavity send cool blood to the brain, so
breathing through the nose or cooling the forehead cools the brain
and eliminates the need to yawn, says Gordon Gallup. He argues that
brains operate more efficiently when cool, and that yawning
enhances brain function. "According to our hypothesis, rather than
promoting sleep, yawning should antagonise sleep," he says.
"Paratroopers report yawning before they jump," says Robert Provine
of the University of Maryland, Baltimore County. "Yawning signals a
transition between the behavioural states of wakefulness and
sleepiness, and boredom to alertness."
From issue 2610 of New Scientist magazine, 02 July 2007, page 14
--
((Udhay Shankar N)) ((udhay @ pobox.com)) ((www.digeratus.com))
