Laughter and Grief

A few weeks ago, I got an email wondering why people sometimes "break into uncontrollable laughter or smiling when faced with terrible situations, like death or illness." Where does this perverse emotional reaction come from? Why do we smile at the most inappropriate times?

I looked into the peer-reviewed literature and didn't find much. While there have been some interesting fMRI studies of our comedic circuits, I don't think that references to the left posterior temporal gyrus explain...