I am not sure, but my intuitions are: + Portrait paintings predating photography don't portray people smiling in that way...nor do most post-photography portra

I am not sure, but my intuitions are: + Portrait paintings predating photography don't portray people smiling in that way...nor do most post-photography portrait paintings including present day portrait paintings. + The selfie smile seems a recent addition to visual literacy. But I could be wrong and don't care if I am.