Dr. Matt Walker

No, you have experienced some degree of what I've just experienced.

How does it do that?

Because your brain has a system inside of it that mirrors my action states and it's called a mirror system.

And you can imagine why it's very good to understand the action and emotional states of others for pro-social capacities and all of that good stuff.

And one of the things that can also happen with this mirror neuron system is that it mimics yawning.

So when you yawn, my likelihood of yawning increases too because my mirror neuron system is matching your yawn.

And what's interesting is that we know other species also have a mirror neuron system.

And that means that when you yawn, there is a statistically higher chance that your dog will yawn and it's cross species.

So when your dog yawns, there's a higher probability that you will yawn.

And we've got this data and it's very clear.

One of the other interesting theories though, is that when species that are cooperative species, for example, a pride of lions,

When one of those lions yawns, firstly, many of the other lions will yawn in a contagious fashion.

But then consequently, there is a collection of actions that happen after that contagious yawn.

And so some people have suggested that the yawning is a way to enact cooperative group behavior.

That's another theory.

The final theory, number four, which I think has the best evidence for, is not the gaseous exchange balancing of carbon dioxide and oxygen.

But when you inhale oxygen from the outside, it's usually cooler.

than your core body and brain temperature.

And 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 beginning to increase.