photo: By Daisuke Tashiro - Flickr, CC BY-SA 2.0, https://commons.wikimedia.org/w/index.php?curid=41915637
Well, don't ask me, I haven't a clue, but it's interesting how efficient that short gasp at the beginning of a yawn is. If you want to sing, or play a wind instrument, observe what you do at the beginning of a yawn, because that's the way to get lots of air in quickly and quietly for musical purposes.
No, no, that's all right. All part of the service.
Anyway, here's another question: why is yawning catching?
Again, no one knows (though one idea is that it's to keep a group of animals alert) but it's a widespread phenomenon. Even reptiles will sometimes yawn in imitation of a colleague. Birds sometimes do the same thing. You can even catch a yawn from a member of another species.
But why do we yawn? I mean, if we needed more oxygen then we could just breathe faster.
Well, yawning might cool down the brain, or signal to your friends that it's time for sleep (or to stop talking about their holiday). On the other hand baboons yawn as a threat; guinea pigs yawn to be bossy; and penguins yawn when chatting up a potential mate.
Snakes yawn to put their jaws back together after a meal.
So the real expert here, of course, is you.
Why do you yawn?
Worth thinking about, isn't it?
Thing To Do Today: yawn. This word comes from the Old English gionian, and is related to the Old Norse jgā, gap.