What is the purpose of yawning and Why we yawn more while there is a cool breeze?I know little, that the yawning is for getting more oxygen. But I...

Actually, the idea that people yawn to get more oxygen has
been discredited in recent years. There has been a lot of research on this, and a number
of theories have been tested. Some studies suggest that yawning may cool the brain
slightly, allowing a clearer thought process - this may be why we yawn when bored or
stressed.

The best-supported theory connects to yawning in
the evening and when we are tired, and it has to do with the fact that yawns are
contagious as well. Researchers believe that a yawn may be a social signal for a group
behavior - when one member of the group gets tired and begins to yawn, others in the
group start to yawn as well, and it helps their bodies synchronize to get ready to sleep
at the same time. This has obvious advantages for groups that include youngsters - the
parents can only sleep soundly when the babies are sleeping as well, so keeping sleep
cycles in sync is very important from an evolutionary
standpoint.

Most mammals exhibit yawning behaviors similar
to humans, so that tends to support these theories as well.