I have always been fascinated about why humans yawn and indeed that it is so contagious! Is it because we are tired and need more oxygen? Or as some claim to take in more air to cool down our brains?
I found this clip on YouTube whereby someone goes to different cities around the world and yawns in public to see if they will also yawn!
Why not try your own little social experiment; when for example sat in the doctors office take a big yawn and see how many people around you also yawn! Studies have shown that it appears to be only children and adults over the age of 4 that yawning affects, why is this? What is different below the age of 4?
Enjoy the clip!