Ever find yourself stunned, then annoyed, then offended to see the person you're talking to yawn?

That's a natural reaction.

Then again, yawning is a natural process.

And that natural habit we humans share with many other mammals doesn't necessarily signal a lack of interest - or a lack of sleep.

As The Wall Street Journal recently reported, a growing body of scientific research supports the proposition that creatures often yawn simply to cool their brains.

Experts have also recently re-confirmed that yawning is contagious. That is, people who see other people yawn often start yawning, too.

But why?

Andrew Gallup, an assistant professor of psychology at the State University of New York at Oneonta, has suggested that yawns bolster collective defense by keeping minds alert. From that Journal story:

"In a 2012 study published in the Journal of Comparative Psychology, Dr. Gallup and fellow researchers compared yawning among groups of four parakeets, some of which were startled by a loud noise. Yawning became more contagious in groups jolted by the noise but not in the others. Dr. Gallup theorizes contagious yawning may be a method for promoting 'group vigilance' against potential predators or other threats."

However, Dr. Gallup also is now advancing the yawning-as-brain-cooling notion.

And considering the threat some hotheads in our species pose, cooling the brain by yawning sounds like, well, a cool idea.