Justin Bieber Justin Bieber Justin Bieber — but anyway, and more importantly, and not unrelated, here's something Ben Montgomery once wrote about mug shots
In 1892, Charles Darwin suggested that facial expressions don't just indicate an emotion, but actually contribute to the emotion itself. Facial expressions aren't more important than memories or thoughts, he wrote, but they can cause an emotional response.
The theory has been tested and retested. In the early 1990s, researchers found that simply prompting people to smile made them happy.
If that theory holds true in jail, maybe smiles are about survival.