What's the closest we've ever come to world peace?

Disagreed. I see “peace” as being more than simply the absence of war. It’s the absence of violence and subjugation of all kinds. I’d even include the lack of ecological destruction as part of “peace”.

That’s not accurate at all. The Neolithic refers to a specific time period, but most of the evidence clearly points to very high rates of violent deaths in most premodern societies. Check out War Before Civilization. http://en.wikipedia.org/wiki/War_Before_Civilization

It’s a common mistake to characterize Neolithic humans as living in unfortified dwellings and that therefore war must not have been a problem for them. There actually is evidence of fortified Neolithic dwellings and there’s many examples of human remains from the Neolithic that show trauma from man made weapons.

Japan surrendered in August 1945 and the Chinese and Greek Civil Wars didn’t start until March 1946. So there was a seven month period of peace.

Pretty sure there was some sort of fighting going on-for example the Soviets were fighting Ukrainian rebels who’d sided with the Germans well into the late '40s (when they were being supported by the CIA).