[HN Gopher] Brain size drives differences in yawn duration acros...
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Brain size drives differences in yawn duration across mammals and
birds
Author : vnglst
Score : 130 points
Date : 2021-05-16 06:36 UTC (16 hours ago)
(HTM) web link (www.nature.com)
(TXT) w3m dump (www.nature.com)
| The_rationalist wrote:
| Why is yawning highly correlated with fatigue then?
|
| Why is yawning socially contagious?
|
| Can't the thermal hypothesis be measured in lab?
|
| The brain size correlation has a co-founder variable: Lung
| size/capacitance.
| kburman wrote:
| Doesn't explain why yawn is contagious
| csunbird wrote:
| The word "yawn" triggered me and now I am yawning constantly.
| da39a3ee wrote:
| I find it a bit sad that whimsical/mundane science
| interests/amuses people. It's also sad that educationalists
| mandate that science taught in schools should be "relevant to
| students' lives". So a bunch of apes on a vegetated rock hurtling
| through space learn how to read the nutritional info on the back
| of cereal boxes instead of thinking about the genesis of time,
| matter, energy, information, and life from fucking nothing.
| ggm wrote:
| Ig-nobel worthy??
| jerrysievert wrote:
| now explain why when you see a cat yawn, you have a compulsion to
| say "big yawn!"
| temptemptemp111 wrote:
| Drives? Correlates! "Scientists" are literally brain dead.
| wizzwizz4 wrote:
| But how long are their yawns?
| ekianjo wrote:
| The model hardly predicts anything, or then the data is super
| noisy. It's not very convincing to express things with certainty
| when your model hardly fits the data.
| ekianjo wrote:
| > Our species-level measures of average brain mass, body mass,
| total neuron count, and cortical and pallium neuron counts were
| highly skewed. We therefore log-transformed these measures
| prior to statistical analysis.
|
| Most of the yawns were collected in non-controlled conditions,
| and then the rest of the data is completely junk, so this whole
| paper is garbage.
| kruxigt wrote:
| Why do we need to cool our brains when we are tired and not for
| example when we are exercising or thinking hard or in a hot
| environment?
| exporectomy wrote:
| My totally made up guess is when we sleep our brains operate at
| a lower temperature than awake, regardless of activity. So to
| quickly transition from waking temperature to sleeping
| temperature, maybe yawning does a rapid cooling that's then
| maintained by normal slower-acting processes.
| op00to wrote:
| Maybe you are tired, and thus need to cool your brain.
| emptysongglass wrote:
| Doesn't read like sound science when all of my 6 pet rats yawn
| longer than I do.
| exporectomy wrote:
| I don't think they found absolute brain mass was correlated
| with yawn duration. They scaled brain mass in some complicated
| way that might put rats above humans for all I know:
|
| "we calculated residual brain mass measures from a
| phylogenetically controlled linear regression of the respective
| brain measure on body mass"
| true_religion wrote:
| There is a chart:
| https://www.nature.com/articles/s42003-021-02019-y/figures/2
|
| Humans are above rats in this chart in both yawn duration and
| brain mass.
|
| Rats are above dogs though.
| [deleted]
| KMag wrote:
| Read The Hitchhiker's Guide to the Galaxy, and post back here.
|
| Minor spoiler: mice (okay, not rats) are projections into our
| universe of immensely powerful trans-dimensional beings, or
| something like that.
| emptysongglass wrote:
| Makes sense as I really seem to be their pet most of the time
| or worse a glorified janitor: the "poo shoveler".
| sebmellen wrote:
| Scared me for a moment there, I've killed upwards of 40 rats
| during this pandemic (outside). They seem to have gone
| rampant with the onset of COVID.
| donkarma wrote:
| Wait until you see the mouse plague in Australia
| Quasimarion wrote:
| Honestly the charts in the paper is not very convincing. The
| outliers are all over the place and there is hardly an
| association judging from naked eye.
|
| (e.g: imagine seeing figure 4 without the model prediction in the
| background)
| wholinator2 wrote:
| Agreed, it looks like they may have even missed a U-shaped
| quadratic association. If were doing pure curve fitting it'd
| work way better with those data. For real though, very
| unconvincing graphs.
| stubish wrote:
| I don't understand why I would need to cool my brain more when
| I'm tired. I'm not buying the theory that yawns are for cooling
| brains without more details.
| tediousdemise wrote:
| I think sighing, rather than yawning, makes more sense with the
| brain cooling theory.
|
| When we are distressed, we release cortisol, which is a pro-
| oxidizing free radical that raises body temperature and blood
| pressure. Signing involves a fast and prolonged exhalation of
| air. We tend to sigh when we are distressed, so it possibly
| serves as a way to cool ourselves down similar to an exhaust
| fan on a desktop chassis.
| vnglst wrote:
| I read somewhere that when we fall asleep our body temperature
| is lowered a bit, maybe that's what's happening?
| chmod600 wrote:
| To go to sleep your body temp needs to drop a couple degrees.
|
| https://www.sleep.org/does-your-body-temperature-change-whil...
|
| Maybe yawning helps you get to the right temperature.
| loceng wrote:
| Could just act as a little nudge in the right direction.
| londons_explore wrote:
| I'm not buying the brain-cooling theory because a couple of
| yawns won't lead to anywhere near enough evaporative cooling to
| chill the brain by a few degrees. Also, the brain has a very
| very good blood flow with the rest of the body, so you really
| have the cool the whole organism.
| tediousdemise wrote:
| The only area of the body yawning could have any kind of
| immediate cooling effect is the soft palate in the rear upper
| portion of the mouth--the part responsible for brain freezes
| when eating ice cream. I don't think ambient air passing over
| that palate would create a measurable change in brain
| temperature.
|
| Yawning always seemed, to me, to go hand in hand with
| stretching. I believe the reason we yawn is one in the same
| with the reason we stretch. By yawning, we are effectively
| stretching one of the few internal organs under our direct
| control: the lungs. It stretches the muscles involved in
| breathing, releasing trapped lactic acid built up over a long
| day of automated breathing. It improves blood oxygen
| concentration, which improves wakefulness and attention,
| which is exactly what you need when you are fatigued. Deep
| breathing also reduces anxiety, which is why breathwork is
| heavily incorporated in meditation.
|
| I think the contagious aspect could be an evolutionary
| behavior. Social mammals tend to work in groups, and
| "contagious" yawning was likely naturally selected for since
| all members of an exhausted group who yawn would be more
| awake and alert in the event of an attack or when hunting
| prey. These are physically strenuous (and tiring) activities
| that directly affect the survival of the organism.
| thatcat wrote:
| It changes air flow by stretching the fold between mouth
| and sinus, maybe it is a pre-sleep sinus stretch.
| montebicyclelo wrote:
| There's also the social aspect of yawning - seeing someone yawn
| triggers a yawn... Maybe brains like to maintain a similar
| temperature to nearby brains.
| elb2020 wrote:
| It's quite possible that it _is_ a social signal, I think.
| Something designed to facilitate a non-spoken syn-ack
| handshake between members in a social group. I see you, you
| see me, I see that you see me, end of transmit.
| batch12 wrote:
| Hell, for me seeing a video of someone yawning can make me
| yawn. Even reading these comments... I seriously yawned three
| times just thinking about people yawning.
| montebicyclelo wrote:
| Just to clarify, the hypothesis in the post above was
| intended to be humorous.
| londons_explore wrote:
| Or yawning is just a communication mechanism, formed in a
| time before using words became commonplace and maintained
| because it works.
|
| It might also be a type of communication which goes against
| the typical 'pack' animal communication hierarchy. It might
| make sense for the pack to sleep when _any_ of the pack is
| tired, rather than waiting for the alpha-dog to feel tired.
| 'contagious' yawning allows that.
| ZuLuuuuuu wrote:
| For me, even reading the word "yawning" so many times
| triggers yawning.
| operatorius wrote:
| Doesnt adenosine improve bloodflow to the brain when we are
| tired? If that is true, increased bloodflow should increase the
| brain temperature as more blood circulates and exchanges heat
| 988747 wrote:
| I guess because your brain overheating is what's making you
| feel tired in the first place?
| taneq wrote:
| That seems pretty easy to falsify. I still get tired in cold
| environments, do you?
| zeta0134 wrote:
| I actually have an easier time maintaining flow in cold
| environments. I keep my house pretty chill and warm the
| rest of my body with warm clothes. Summer in South Texas
| was miserable for me, so I moved father north and could not
| be happier with the change.
|
| It's not that I don't still get tired, of course I do. More
| that I'm less affected by the ambient heat.
| 11235813213455 wrote:
| Probably because the brain is what takes the most energy for us
| amarant wrote:
| I'm definitely citing this study next time I'm sleepy and someone
| comments on my constant yawning
| [deleted]
| purplecats wrote:
| title doesn't state if larger size is positively correlated
| with more frequent yawns :)
| airstrike wrote:
| You're giving people far more credit than I would! You can
| get a ton of mileage out of the most spurious of
| correlations...
| amelius wrote:
| drives -> correlates with
| erulabs wrote:
| I just saw my unborn son yawn in the womb on an ultrasound today
| so this brings me a bit of silly joy - knowing his brain folds
| are just developing and he might be cooling them! That said, the
| stats nerd in me doesn't buy this study outright.
|
| I'd personally hypothesize that yawns, like almost all other
| emotional displays (smiling, laughing, worrying, eye dilation)
| are simple pre-language communications. It's useful for a pack of
| animals to know when one animal is tired - yawning is contagious
| because it's advantageous for the pack to have a similar sleep
| schedule - and to be aware of how each other feels. Our faces
| display our emotions clearly as a form of communication to
| others. We developed whites in our eyes, for example, so we can
| track the attention of our pack-mates. It's easy to forget that
| biologically, spoken language is a brand new invention - but
| communication is extremely ancient.
| just-ok wrote:
| > yawning is contagious [...] to be aware of how each other
| feels
|
| To this point, fascinatingly, psychopaths are immune to
| "contagious" yawns, highlighting their inability to empathize
| with others.
|
| https://www.psychologytoday.com/us/blog/your-online-secrets/...
| etangent wrote:
| > I'd personally hypothesize that yawns, like almost all other
| emotional displays are simple pre-language communications
|
| The trouble with that hypothesis that even very primitive
| vertebrates that have or have had almost no social history also
| yawn.
| erulabs wrote:
| Agreed - but it's a chicken/egg issue there. It's not clear
| that behavior is a precursor to social groups. Social groups
| with no communication behavior would be very hard to
| maintain. Hard to say tho for sure which comes first
| b4ke wrote:
| Yawns are caused by changes in the souls position relative to
| others.... why it is contagious, and why someone who is
| cognitively your superior will cause you to yawn in their
| presence. I know it sounds nuts, but they know more than they let
| on.... just look for the well seal ;)
| Madmallard wrote:
| This is hilarious
| sulZ wrote:
| Is this a reference to something that I'm not picking up on?
| montebicyclelo wrote:
| Yawning cools the brain?!
| ElvisTrout wrote:
| Yes, that's it's purpose. Hence why the results of this study
| is not really surprising.
| cinntaile wrote:
| We don't know if that's the purpose of yawning.
| [deleted]
| rukuu001 wrote:
| I researched this independently when I started yawning madly at
| the gym
| jdonaldson wrote:
| Ok, glad to know I'm not the only one to do this. However,
| the plot thickens... why is this happening?
| [deleted]
| [deleted]
| b4ke wrote:
| Ha los are a real thing, praise be.
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