why is yawning contagious?

[bristewart]

why do people often feel the need to yawn just because they have seen others yawn?!

[WaldoMcFroog]

Yawning causes an increase in the amount of oxygen taken into the lungs, and by extension, the bloodstream and ultimately the brain. Other people yawn because psychosomatically, we fear that the first person to yawn has done so becuase of a low oxygen level. We then try to ensure our own intake is high enough to ensure our survival.

[WaldoMcFroog]

Yawning causes an increase in the amount of oxygen taken into the lungs, and by extension, the bloodstream and ultimately the brain. Other people yawn because psychosomatically, we fear that the first person to yawn has done so becuase of a low oxygen level. We then try to ensure our own intake is high enough to ensure our survival.

[THEGREATONE]

There is a theory that before we evolved into the species we are today we were apes or at least a close relative of them. The yawn to an ape is a warning of danger and this is instinctivly passed on throughout the group until everyone is aware that there is a potential threat. Somehow we still have those thoughts subconccioussly whenever we see someone yawning or when we yawn ourselves.