Something we wll know, but I have no clue why. When we talk about the topic, or when someone yawns, bingo everyone around you starts up. Since I started making this post, have yawned 4 times already just thinking about it.

Does anyone have and medical explaination why we yawn when others do. From what I know, its typically set on by the bodies need for more oxygen , but when the guy ( hold on...need to yawn again ) next to yawns, irrespective of you energy levels, you wannt follow suit.....

Interesting if any one know why humans have this habit. (or is it kinda a cave man thing which makes sure everyone sleeps at the same time when the first one gets tired ( <deleted>, yawning again......need to go )

I believe that no one knows for sure. Some say it has to do with increasing oxygen because when we are tired or bored we don't take in as deep of a breath as usual. I'm not sure that is the case though, since if you yawn around others, they too will likely yawn. It might just be a way of telling the tribe or flock or whatever that it's time for sleep. This makes sense since many different animals do it.

I believe that no one knows for sure. Some say it has to do with increasing oxygen because when we are tired or bored we don't take in as deep of a breath as usual. I'm not sure that is the case though, since if you yawn around others, they too will likely yawn. It might just be a way of telling the tribe or flock or whatever that it's time for sleep. This makes sense since many different animals do it.

Thank was my un-scientific take on it too..... always interested me why this is so.