Serious declines where? Not in Mozambique, not in Serbia, not in Gaza. The West is NOT the world. What about that is so hard to understand?

Pinker's assumption (and that is a very key word) is that band hunter-gatherers were chaotic and vicious - which seems entirely unlikely since there is no archeological evidence of war until 10k years ago, among a vast array of other reasons that this supposition is just plain wrong. He doesn't say that violence has increased since 12k years ago - he says that it has decreased since the beginning of time - and he's wrong.