Once upon a time, a very long time ago, animals evolved and developed into species. For some reasons, apparently clearly understood only by Darwin, these species separated and the idea of "us-ness" and "them-ness" was born. “Us” is good and “them” is bad.
Then there evolved families of humans who formed themselves into different groups called “tribes”, obviously borrowing the ideas from the animals. They invented private languages and the idea of “us” and “them” became an art form. Everyone who is not “us” look funny, smell funny and “us” cannot understand a word “them” say.
Of course, it was permissible for the “us” tribes to steal women from the “them” tribes because women were really of no consequence whatsoever and it was easy to replace a worn-out one by promising a hungry one much meat on the table . . . or whatever. Which just goes to show you that things have not changed much. In fact, to this very day, women form a sub-group of “them” among the main “us” group of men, who still continue to feel very superior to “them”.
And so it has gone down through the ages until today. The tribes grew and prospered, all the while holding firmly to the idea of “us-ness” and “them-ness” because it is very ego-pleasing to be a superior “us” among all these inferior “thems”.
Of course, all the “us” groups tend to ignore the fact that “thems” make up all the rest of the human population of the entire world!
So . . . .
Germans hate the French, English and Russians, somewhat respect Americans and anyone else who carries a big stick, suspect the Japanese of being more intelligent and distrust everyone else, particularly those who can make decisions without consulting at least three other people to reach a consensus or who tells the truth about anything.
English hate the Germans and French, feel very superior to everyone else . . . and have just discovered how small their island kingdom really is without their colonies.
Japanese are stll inscrutable Italiens respect only the Pope and the Mafia, and the French hate everyone and everything not French.
Russians cannot seem to make up their minds but derive much pleasure from hating Americans . . . and each other.
Jews are paranoic and think everyone is out to get “them”, which has, of course, been the case for several thousand years.
And Americans? Well, our ethnic mixture is diverse enough to give all of “us” someone called “them” to hate happily ever after . . . which is how a story that begins with “Once upon a time” should end, don't you think?