As a kid, seeing old photos in history books and elsewhere, I came to the conclusion that, in most "dignified" pictures, the "white men" mostly came off looking constipated or as if they were smelling something unpleasant, whereas the Native Americans tended to look grim and/or pissed off. Sorta gave me my visual definition for the word "stoic".

This is just my opinion, mind you, but I think it's partly a feature of facial structure. Imagine my surprise when I found out, in my late teens, that apparently my own face, at rest and not feeling anything in particular, is usually interpretted as grim and/or pissed off. Then I noticed the same in the faces of my own family (I guess familiarity had made it so "normal" to me as to pass notice). All of whom show the evidence of our own N.A. heritage to a greater or lesser degree. And we all have had a problem with being perceived as stand-offish and glum (rather than warm and fuzzy).

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It is hard to convey five-dimensional ideas in a language evolved to scream defiance at the monkeys in the next tree. -- The Science of Discworld III: Darwin's Watch, by Terry Pratchett, Ian Stewart & Jack Cohen