World cooperation? What fantasy are you living in? The world is still a collection of nation-states (in best case scenarios, ignoring the many many "countries" that are in eternal tribal warfare, whether it be ethnic, religious, cultural, etc.) vying with and challenging each other, "cooperating" only when it is in their interest to do so. Yeah the human brain wasn't "evolved" enough to give up war. Well that's not necessarily true. Many tribes, ideologies, religions, etc have had the same approach to violence and war throughout human history. What happened to them? Oh right, they got absorbed or conquered. I wonder why.
What makes you think humans are any different now psychologically and biologically than they were tens of thousands of years ago, much less two thousand? Post-modernists are frigging delusional. You guys need to actually go and experience life outside of your first world bubbles, the only places in the entire world where this ridiculous hippy shit is not ridiculed as a pipe-dream.