have facial expressions evolved, like language, so that's they're just different these days?

you can't imagine someone 200 years ago doing this expression

http://www.bact.org.nz/fileadmin/clients/bact/images/soulfood/hi_res/tony_open_mouth.jpg

and it seems that whenever you encounter people that are dressed up to look like they are from the past they do expressions that you don't really see in day to day life

http://www.ukgamesexpo.co.uk/images/slides/EXPO10-140.jpg