Still a Mystery
It's important to remember that for all of these theories, we can not say for sure why people yawn and why it is contagious. There are many compelling ideas out there, and there is no scientific consensus about which is correct. We can not say for sure if we yawn to cool down our brains or if we do it to keep alert. And again, as long as more pressing medical issues remain to be studied, we may never know the answer for sure. But the next time I see someone yawning, and I can’t help but do the same, I’m going to choose to take it as a sign of the human being’s capacity for empathy. That will do a lot more to help me sleep at night than the thought that my brain might be too hot.
