> Historically, the only thing that prevents tribes of human animals from blowing each other up is mutually beneficial economic cooperation.
That's correct, until someone thinks that he is being screwed and does not see mutual benefit. Mostly what Lenin explained in "Imperialism, the Highest Stage of Capitalism"
Do you really think that WW2 happened over whether Poland would be invaded? I think you are confusing cause and effect.
Same as thinking that WWI happened due to the assassination of Archduke Franz Ferdinand.