why do people yawn?

We know that yawning appeared early in vertebrate history and that and most other animals with backbones, including fish, turtles, birds, and crocodiles, engage it. But we don’t know why it appeared. [...] People begin to yawn early in their lives. Indeed, yawning has been observed in three-month-old fetuses — evolutionary evidence of how ancient the behavior is. It’s the contagious quality of the activity that’s especially intriguing. [...]

“Contagious yawning definitely does not involve a conscious desire to replicate the observed act,” Provine observes, but it’s possible, as some research into brain activity suggests, that someone who “catches” a yawn may be unconsciously expressing “a primal form of empathy.” Thus, contagious yawning can be linked to sociality. Some neurological and psychiatric disorders, such as schizophrenia and autism, that leave patients “deficient in their ability to infer or empathize with what others want,” apparently reduce as well their susceptibility to contagious yawning.

every opinion is very welcome..enjoy urself…

It seems contagious. If you yawn in class, you'll probably notice a few other people will start yawning, too. Even thinking about yawning can get you yawning.

that's very true ^_

i really notices that .

and i yawned tow time while reading this artricle .

thanks man for these great info >>>>

I yawned when i was sleepy,and when others were yawning.