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Hey Friends,
Nina’s Notes is growing!
I’m now sharing interviews with health, longevity and psychedelics experts every other week on Mondays!
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💬 In this note:
🥱 Why Do We Yawn?
📚 Three Body Problem
⚡️ Digging a Tunnel Through Earth
🥱 Why Do We Yawn?
Yawning is a commonplace behavior.
But we often overlook it in discussions of human physiology and psychology.
Its ubiquity across various species and the complexity of its potential causes make it a fascinating subject to research.
Sleep scientist Dr. Matthew Walker dives into four theories in detail in his podcast episode, Yawning Explained.
I break it down those four competing theories about Why We Yawn for you here.
1. Yawning as a sign of tiredness
It's a commonly held belief that yawning is a sign of being tired.
However, this theory is not true.
Research shows that people often yawn when they are bored, even if they are well-rested, indicating that yawning is not exclusively a sign of being tired.
2. Yawning balances your blood gasses
The idea here is that in the process of yawning you take a deep inhalation to increase oxygen intake, and then you make a forceful exhalation to expel carbon dioxide, thus rebalancing oxygen and carbon dioxide in your blood.
To determine if this is true, researchers did some clever experiments.
Researchers artificially increased the oxygen levels, and more importantly, increased the carbon dioxide levels of the participants in the study to answer the question, “Did those individuals start to yawn more when the level of carbon dioxide in the blood went up?”
And the answer was no, people did not start yawning when their carbon dioxide levels were increased.
Proving that this theory is not true.
3. Contagion
Yawning is notably contagious among humans and other species.
(By the way, is anyone yawning yet while reading this? I’m yawning writing it!)
This phenomenon can be attributed to the brain's mirror neuron system, which enables us to mimic the actions of others.
However, that also means that when someone yawns around you, then you will also mirror them and yawn in return.
Other species also have a mirror system. That means that if you yawn, there is a statistically significant increase in the chance that your dog will yawn too.
This effect also works cross species, so when your dog yawns first, there is a higher chance that you will yawn.
This mirroring might play a role in fostering social bonds, promoting pro-social behavior and collective behavior, such as in groups of lions where yawning seems to promote coordinated group activities.
4. Yawning cools the brain
The final and most evidence-based theory is that yawning is a cooling mechanism for the brain.
Inhalation during yawning introduces air from the outside that is typically cooler than the body’s core temperature.
Studies show that when we inhale there is a modest drop in brain temperature.
And when the brain temperature starts to rise, that’s when we see yawning frequency start to increase.
So the next time you see someone yawn, it’s not because we are tired, it’s because our brain is getting warm.
Personally, this makes a lot of sense to me, because I always yawn in the first 10 minutes of a workout even though I’m well rested and not tired.
Now I know that since my heart rate is going up and my body temperature is rising a little, my brain is also getting a bit warmer too and I yawn to cool it down. So cool.
📚 Book of the Week
It’s a book and a show!
The Three-Body Problem by Liu Cixin, translated by Ken Liu
Rating: ★★★★★
I’ve only watched the show so far, and now I'm really regretting that I didn't read the books beforehand.
With the show being this great, the books must be spectacular.
Three-Body Problem is the story of Earth’s first contact with an alien civilization.
Contact begins after a Chinese astrophysicist sends a defiant message into space.
As a result, humans must deal with the consequences of this contact.
It’s thrilling and definitely a show you should add to your watchlist.
Netflix hasn’t announced or confirmed a second season yet.
So if you’re like me and impatient, I suggest adding the next book in the series, The Dark Forest to your “to-read” list.
⚡️ Check This Out
Where would you end up if you dug to the other side of the earth?
The title of the 1970s movie, The China Syndrome, refers to the idea that if you dig a hole through the Earth starting in the U.S., you would end up in China.
Atlas Obscura created a few maps which show the antipode (the direct opposite) of the continents of Earth.
For most people, the place where you’ll end up won’t be land, but water.
As we know, the oceans cover about 70 percent of our Earth’s surface.
If you could fold the Earth, the overlap of land would be surprisingly small.
Argentina & Chile overlap the most with China.
And there is nearly no overlap in North America & none in Africa either.
For Europe, it looks like New Zealand may overlap with Spain. (Let’s dig!)
Edited by Wright Time Publishing