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[Trivia] Why do we yawn?

Discussion in 'Issues Around the World' started by Coriolis, Mar 21, 2006.

  1. Coriolis

    Coriolis Bob's your uncle

    Now, before you Google for an answer (which won't do you much good anyway, because yawning is not well understood), try to come up with a rational answer for the following:

    1. Why do we yawn?
    2. Why does it seem to be contagious?

    Then Google it to see how close you are. There are some good theories, but they are all flawed in various ways, thus making this an interesting problem. :)
  2. Coriolis

    Coriolis Bob's your uncle

    PS: How many of you yawned while thinking about this? :)
  3. Steve

    Steve Is that it, then?

    It's your body's way of drawing in extra oxygen to compensate for a deficiency.
  4. Sir Joseph

    Sir Joseph Registered User

    I think the technical answer is "we're not 100% sure."
  5. Sacchiridites

    Sacchiridites Banned

    I was taught that it's the body's way of releasing carbon dioxides and monoxides. Now, I'll look for the answer online.

    Here's a thought...plants 'yawn' however slowly. It's their way of 'breathing'.

    Perhaps it's contagious because it's not a human's natural way of breathing and while it might be an unconscious release of carbon dioxides/monoxides for one person, it's a reminder to the other person to 'breathe'. Hell, we hold our breath unconsiously when under stress, don't we? Why not react to a visual clue as a 'reminder' to breathe in other ways?

    P.S. I did not yawn or have a desire to while reading this thread.
  6. Coriolis

    Coriolis Bob's your uncle

    Both seem like reasonable answers, but apparently not true.

    From Wikipedia
    A long-standing hypothesis is that yawning is caused by an excess of carbon dioxide and lack of oxygen in the blood. The brain stem detects this and triggers the yawn reflex. The mouth stretches wide and the lungs inhale deeply, bringing oxygen into the lungs and hence to the bloodstream. It is almost certain however, that this hypothesis is not correct. One study documented that this effect does not exist ( "Yawning" by Robert R. Provine, pages 532-539, American Scientist, November-December 2005, Vol 93, No. 6).

    There's also evidence that fetuses yawn -- and since they are not breathing oxygen, then the oxygen/CO2 hypothesis cannot be true.

    From Scientific American
    As for the etiology of yawning, for many years it was thought that yawns served to bring in more air because low oxygen levels were sensed in the lungs. We now know, however, that the lungs do not necessarily sense oxygen levels. Moreover, fetuses yawn in utero even though their lungs arent yet ventilated.​
  7. jfcjrus

    jfcjrus Veteran Member

    OK, here's my theory (which I suggest has as much 'real' science behind it as anyone elses). ;)

    I think yawns are a natural human reflex; when the neurons in our brain get bored with trying to store all the absolutely usless information being submitted and revolt by trying to do something more useful, like sucking some air that they know our body can use.
    And I think that someday we'll discover that neurons can talk to one another, which will explain why yawns seem contagious.

    Can you tell that I don't think much of this research?
    I mean, come on, they're SCIENTISTS, not a schmuck like me!
    And that is the best they can come up with?
    I suggest we give them another $10million grant, to further their study into this important issue.

  8. Frodo Lives

    Frodo Lives Luke, I am NOT your father!

    I believe that a yawn is either:

    A: A release of stress in the muscles around the jaw and neck area that is built up during stress that you get during the day. This helps to relax your muscles for sleep.

    B: A carryover from our ancestors during a time when mankind lived in small groups. It's a sign that it is the time for rest for the tribe or group living together. That is why it seems contagious. When one person sees another yawn, the instinct that it's time for rest kicks in, and so they yawn as well.
  9. Coriolis

    Coriolis Bob's your uncle

    Very interesting theory. Sort of a sleep synchronization mechanism. It still begs the question, however, why this particular physiologic response/reaction exists in the first place. Surely there are other more efficient ways to indicate that it's time for bed. Also, the fact that a fetus will yawn just adds to the puzzle.
  10. Coot

    Coot Passed Away January 7, 2010

    It's not just humans, most mammals that I am aware of yawn.
  11. Steve

    Steve Is that it, then?

    I'm sticking with my original comment. That fetuses also yawn means nothing. Fetuses also masturbate and smile. Yawning is done from a state of rest, the act of yawning results in a large intake of air (try to yawn without breathing deeply). Even suppressed yawns, those ones where you try really hard not to show it, make you breathe in deeply.

    Given that no one knows the "real" reason, I'll stick with "guilt by association" :)
  12. Sacchiridites

    Sacchiridites Banned

    Neat to know. Thanks!
  13. ravital

    ravital Banned

    Talk about yawning being contagious and easily induced, I yawned three times reading the very short Scientific American piece, I was not tired in the least, had no trouble understanding it, not bored, just reading about yawning caused it.

    Then again, you can't go by me.
  14. ravital

    ravital Banned

    Talk about yawning being contagious and easily induced, I yawned three times reading the very short Scientific American piece, I was not tired in the least, had no trouble understanding it, not bored, just reading about yawning caused it.

    Then again, you can't go by me.
  15. Kluge

    Kluge Observing your world for over 50 years

    Don't cats yawn & stretch when they wake up? Isn't it stereotypical to yawn & stretch (& scratch) after waking from a sleep? Yawning is a mechanism to wake up or stay awake... hence the troublesome question from another, "Am I boring you?"
  16. JeremyToo

    JeremyToo Registered User

    Yawning now ....:nut:
  17. ethics

    ethics Pomp-Dumpster Staff Member

    Gladwell went over this topic nicely. He believes it IS contagious. Yawning, from my reading (and it could be wrong) is used in two circumstances. One is when you are about to go to bed, one last gulp of O2 for the rest of the brain. The other is a signal to others that you are bored vs. stressed and you do it when you ARE stressed.

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