Game Theory did a small thing on this, Seeing someone yawn, then yawning yourself, is a short-cut for you're brain, so it can skip doing as much work, and it provided to have some sort of evolutionary advantage, which is why it's become an instant reflex in our heads.
because the person that yawned is getting sleepy from being bored. The other people in the area are also getting sleepy from being bored. So it is not that it is contagious, the situation is who is going to yawn from being bored first.
When you see someone else yawn your brain triggers a response that thinks that the person who yawned is taking all the oxygen around you, so you automatically yawn because of this. that's why people yawn in the first place is because the lack of oxygen to the brain.- science class 101
Yawning when others yawn, the study suggests, is a sign of empathy and a form of social bonding. Kids don't develop this deeply rooted behavior until around age four, the study found. Kids with autism are half as likely to catch yawns. In the most severe cases, they never do.