Why do people smile when a photo of them is taken?

[sanddeamon]

im having a hard time to smile at the camera, fake smile or otherwise :s
plus there is the matter of flashes..damm you flashes!

[phangtom]

Truth be told, I've never seen rich people smile. That says something.

"Although, it is not true that all unhappy people are rich, it is true that most rich people are unhappy."

I like to mess around with J.S Mill's quote :P

[fedaykin]

In my experience, people awkwardly grimace at the camera under the weight of social expectation to smile.

[fool]

In my experience, people awkwardly grimace at the camera under the weight of social expectation to smile.

Yup it's as you say

Anyone not smiling in a photo is pointed out like it's an abnormal thing, especially in group photos

[MacroMagic]

Apparently the act of smiling releases serotonin in the brain. Insofar as other people not liking it when you're not smiling in a picture or a group photo. It may have something to do with an emphatic feeling of sorrow or sadness. And in group photos, well, they probably don't feel comfortable about it or something.

Hey! Warren Buffet is the happiest guy I've ever seen! Come on, you've seen rich people smile, just watch some TV.

I've seen the fake smile called 'cheesin' am I right on the definition?