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  • Almost all animals with a spine yawn.

  • Penguins do it as a mating ritual, snakes do it to realign their jaws after a meal and guinea pigs do it to display anger.

  • So, why exactly do humans yawn? And is yawning actually contagious?

  • If you haven't already checked out our YAWN-O-METER video, click here, or use the link in the description to see how long you can last before yawning.

  • If you're anything like us, you may have even yawned at the title of this video.

  • The truth is, the first time you yawned was likely as a fetus.

  • Babies begin to yawn during the second trimester, and though the reason why is still unknown, it may have to do with proper brain development.

  • In adults, yawns were commonly thought to draw more oxygen into the lungs making you feel less tired, but new research states that this may not be the case.

  • Scientists now believe that yawning has developed as a way of physiologically cooling your brain.

  • Much like a computer, your brain works best at a certain temperature, and tries to avoid "overheating".

  • And it turns out yawning increases your heart rate, blood flow and the use of muscles in your face which are all essential to cooling the brain.

  • On top of that, deeply inhaling cold air can alter the temperature of the blood in our head.

  • But why is your brain hot in the first place?

  • Well, both exhaustion and sleep deprivation are known to increase overall brain temperature, which explains why yawning occurs more in these states.

  • Researchers have even found participants who place warm packs on their head yawn 41% of the time while watching others yawn,

  • as opposed to 9% of the time with a cold pack on their head.

  • So if your head is already cold, you'll yawn less.

  • But what about contagious or social yawning?

  • Humans, primates and even dogs find yawning contagious, and it's most likely linked to empathy.

  • Contagious yawning begins in children around the age of 4-5, and this is when empathetic behavior, along with the ability to identify emotions, begins to develop.

  • In fact, children with empathy-related disorders, such as autism, yawn less in response to videos of people yawning compared to other children.

  • Research also suggests that you are more likely to copy the yawn of someone socially or genetically close to you.

  • Even dogs are more likely to copy the yawns of their owner as opposed to the yawn of a stranger.

  • Finally, mirror neurons also play a role.

  • In our brain, mirror neurons fire when we perform a specific action, view someone else doing the action or even just hear someone talk about the action.

  • They are important brain cells that are used for learning, self-awareness and relating to others.

  • When we view someone else yawn, the mirror neurons in our brain become activated in a similar way, and as a result, we copy the yawn.

  • So, although yawning may occur in people who are literally 'hot-headed', contagious yawning allows us to be cool with the people around us.

  • If you haven't already checked out our Yawn-O-Meter, go try it out and let us know in the comments how long you were able to last.

  • And subscribe for more weekly science videos!

Almost all animals with a spine yawn.

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