Way more than 5000 years. People don't change that quickly.

Given that all of recorded history has taken place in the last 10500 years, and that time has seen a huge diversity of social structures in civilizations across the globe, I think your pessimism is unfounded.

Yes, people are selfish. People also have a great capacity for cooperation and altruism, given sufficient cause to bind them together.

I rather hope that the impending collapse of the biosphere that sustains all life is just such a cause. Then again, we appear to be setting the world on fire at an ever greater pace.

Lol, touche. I hope for all our sake that you are eventually correct, though I fear we'll be extinct before that's ever the case