I read an article that describes how mankind has evolved to instinctively recognize from mannerisms as simple as a wave, the gait of a person’s walk that they are from another “tribe”.  That is nation or ethnic group, which may cause a natural anxiety.  Our ability to overcome anxiety with reason allows for us to come together as nations, of many tribes, many dialects, and many characteristic markers.  However that instinct is ever present.

Instinct

Instantly we know, he’s not one of us, but we ignore
Because it’s not sensible, logical
to assume something bad may be in store
Hair follicles tell us there’s something different here
Nothing we can discern in prefrontal cortex
but something much more primitive, fear
Inherited by the survival of ancestors now long-dead
Nothing we can explain, nor really want to
but we give over to wary reason instead