Why do we yawn?
The short answer is that we still don’t know for sure, but here’s a pretty good (popular) summary of some current research.
The Surprising Science Behind Why and When We Yawn : The New Yorker.
Why do we yawn?
The short answer is that we still don’t know for sure, but here’s a pretty good (popular) summary of some current research.
The Surprising Science Behind Why and When We Yawn : The New Yorker.