I saw this video and thought it should go here. It is very interesting. It talks about how we learn facial expressions to survive in our specific culture. I wonder what effect this has if any on our internal emotions.
I have to say, jump to 23:42 if you want to see the very creepy, good stuff. Its called "microexpressions". Tell me what you think!
http://www.youtube.com/watch?v=m72bqvf_qDg
I also wanted to add this short video about it. If you don't have time to watch the long one, this one is good too. He says how people can learn to spot microexpressions on the internet and it only takes about an hour to teach someone how to do it.