Why are yawns contagious?

I believe its called “mirror neurological syndrome” some can even get sick justbecause of mass hysteria thinking they are sick because people around them are ill.

There is a MythBusters episode that covers this but I don’t remember the outcome. Might find it on YouTube.

My theory:

People yawn when not enough oxygen is getting to the brain. Thus when a person yawns he/she takes a massive amount of air in at once to satisfy the need for air.

Once that person takes in that air there is a deficit of air where once there was none. This causes the surrounding people to have a limited amount of air going to their brains thus they need to yawn as well.

Why is gagging contagious? Why, when we are young, do we often laugh when we see someone crying? The emotions are badly understood. Sociobiologists talk about the herd instinct; it is safer to behave like the tribe, rather than getting bonked or speared

Autistic children do not have “sympathy” yawns.

Interesting, my son has a form of autism but can’t say that I have ever noticed.

i’ve heard that the “contagious” yawn is a sign of empathy, too.

Outside of humans, many mammal societies use yawns as a form of aggression or dominance, i.e. “Look at my huge teeth. Don’t mess with me or they will be in your shoulder and you will be in pain.” So I’m pretty sure the contagion is exclusive to humans, but I could be wrong.

My coworker yawned after catching a dog yawning in the car next to her.

I just yawned after reading all these posts about yawning!!!

I wonder if it’s an evolutionary/survival thing. Maybe one person back in the day yawned to get some extra oxygen to the brain, due to poor air quality or something. Those around him/her subconsciously picked up on the message and yawned as well to get their brains some extra oxygen, thus ensuring their continued survival with healthy brains. Now we don’t have the poor air quality threatening our survival, but we have the residual reactionary yawning. Kind of like how we evolved to have allergies to pollen (runny noses, watery eyes) because those allergens could threaten our systems once upon a time, so we evolved allergic reactions to flush out the allergen. Now pollens and such are not a threat anymore, but we still have the reaction. Or so it’s been explained to me when I am going through a box of Kleenex an hour and crying, “Why, why, WHY?”