reason why we yawnThere is never a true reason why we yawn, and why it is so catching. Do you know?

Why do we yawn and why is it so catching.
it does allow us to take in more oxygen and expel carbon dioxide, it also increases heart rate a bit. Yawning could keep the brain aroused in situations where sleep is unwanted - like first period maths lessons or 9 am meetings.

Why we yawn when we see others yawning has baffled scientists for ages and a number of suggestions have been put forward to explain this phenomenon. What we do know is that yawning is an involuntary action - our brain does it without us thinking about it. Even very young babies yawn, showing that it's a built in action (Chimps do it too by the way). Just thinking about yawning can trigger the bit of the brain that causes a yawn and, chances are, when reading this, you will end up yawning at least once!

My favorite explanation for why we yawn when we see others yawn is that it's a throw back to the days of our ancestors, when we lived in groups. Yawning could have been a sign thareason why we yawnt it was time for the group to go to sleep or change activities. It's important, after all, that all group members were ready to do the same thing at the same time.

It appears that there is some relationship between yawning and our ability to 'put ourselves in other peoples shoes'. Not all people can 'catch' a yawn when they see someone else yawning and these people also appear to be less able to understand things from other people's points of view. This is an important skill for being able to get along with other people - it lets you sympathize with them and understand how they feel. So yawning is maybe just a by-product of us being able to use our own experience to understand how others are feeling. Maybe it's due to accidental 'cross-wiring' in the brain that occurs when the 'thinking about others' part of the brain is stimulated or could serve some other purpose that no one knows yet.
We yawn to open up the windpipe and let more oxygen in, reason why we yawntherefore giving us a little more energy than before!
No one knows why we yawn. We see another person or an animal yawn, and we do it to. Its not just restricted to humans--I've made my dog yawn a few times. Also, you can see someone on TV yawn and you have to as well. Also, someone on the radio is yawning and you also have the impulse. Who hasn't yawned while reading this paragraph?

Check out this link:

did you know fetuses yawn in the womb?
Like the other answer said, to allow more oxygen in. That helps us feel awake. It catches because (in like, primitive times) we would see someone else yawn and then your sub conscious would go 'oh dear, the oxygen is running out!' (yawning lets more oxygen in, and one reason to do that was because there was a limited/low supply of oxygen, so you take in more) and copy that person, taking in more oxygen yourself.