Why do we yawn?

Question

?????

Answer 1

Actually scientists have no explanation.  The theories of we yawn because we need more oxygen or need to expel more carbon dioxide were proven false recently.  Scientists know what triggers yawning but they have no idea what benefit it has to our bodies

Answer 2

no one really knows why we yawn but they do think it is because were low on oxygen and supposed to help us get more.

Answer 3

it's better for you than smoking? i give up

Answer 4

When we are low on oxygen we yawn to get more...