bears yawn, cats yawn , most mammals yawn .
whay do yawn ? no realy knows the answer.
we do know that everyone yawns in the same way. first you open your mouth slowly. your mouth stay open for about five seconds . then you quickly close your mouth.
we also know that yawing is contagious , or catching .
when you see someone yawn , you yawn ,too.
many people say that they yawn because they are bored or tired. this might be ture .
however we know that people also yawn when they are excited or nervous .
olympic runners , for example , often yawn before a race . why is that ?
some scientists believe that yawning makes you more alert .
when you yawn , you breathe more deeply . you also stretch the muscles in your face and neck . maybe this makes you feel more alert.
scinetists dont spend much time studying yawing doesnot hurt . it is just smoething we do...