Jeremy Dean at PsyBlog has an interesting post on the relationship between culture and control of facial expression. Some researchers contend that, among cultures that have been studied, Russians exert the most control over facial expression in public, while Americans exert the least control. It has also been suggested that collectivist cultures encourage conformity and, therefore, discourage facial expression, while cultures that encourage individualism are more relaxed about expression.
This discussion reminded me of Michael Moore's ridicule of the American tendency to smile broadly and readily. Such knee-jerk ridicule may satisfy pretentious clowns like Moore, but it reflects a naive indifference to the possible adaptive value of cultural differences in facial expression.
One (highly speculative) thought I've had about the adaptive value of the broad American smile is that in a culture of immigrants who had to overcome natural xenophobia, one way strangers might quickly establish their intentions is the clear display of facial expression. Facial expressions are universal across cultures and understood regardless of spoken language differences.
A warm smile can, in some instances, bypass the wariness that is sometimes evoked by the unfamiliar and neurologically facillitate a sense of ease between people. Among other things, an open smile may convey that "I am friendly. I am not a threat." And, if we are considering the full range of facial expressions, perhaps amplified facial expression evolves as an adaptive cultural trait that serves a more important communicative function within societies that are culturally and linguistically more diverse.