God, I hope there will be no "next war", at least not between countries - it'll suck more than ever - the fights are not what they used to be before WW2 - one nuke (or even a slightly bigger conventional bomb) destroys a city, people fight with assault rifles that can kill you from a distance before you realize what happened, and I have no doubt armies will just attach machine guns to automatic platforms and leave them to kill anyone/anything who gets close ("close" is up to a kilometer currently - yes, they're already that accurate on a good day).

An economic war, a cold war, a new space war or anything else that does not require people fighting directly - I agree, that would help progress (and birth rates), even though it'll kind of suck. But I really hope we'll be able to get by simply with competition (in starting new businesses, inventing new things, etc.), even though it sounds naive.

Also, why did you leave out Europe, Arabic countries and Russia (which by the way is thinking of a new union with former USSR republics, that would be interesting)?

It might be a bit more complicated than that. The fertility rates are sometimes higher among:
a) groups of people that have lower IQ/sense and that simply don't give a damn about future. And it doesn't matter, that they are poor. The just go for their instincts.
b) groups of people that live according to traditional patriarchal system (muslims etc)
c) groups of people that are living without fear of future - the Economy is booming / government is spending money for houses/flats for new families etc. (Czech Republic during socialism, maybe USA after WWII etc.)

I live in capitalistic country. And I am pretty sure, that we are here not that much stressed about work / career as people in Japan. I love to work, but until I'll have enough money in savings, until I'll have my house / flat, until I'll be sure, that my future wife wont just one day start bitching (which is problem with lot of nwdays lads), leave me for some jerk and take the kids with herself... the situation is just to unstable to have kids.

And yet, one must be somehow grown up, to freely choose the option to have kids.

When there will be unlimited stability, peace and love(!)... there, I guess, could be lots of kids in such a society. But... unfortunately... such a society can't ever exist, as long as people rule themselves.

But anyway... maybe by simply generating fear of war might be the fer. rates brought up, because the instinct to multiply might get louder. Hence maybe my text above was just waste of time.

Good bye

"No longer forced to confront mortality and with no externally unifying cause, people start living for luxury, pleasure, and consumption. They stop having children. Birth rates fall off."

True for almost all eras but how about our current era where military supremacy could be down to certain technologies? It doesn't have to be people-powered nearly as much as before.

I think we are already fighting WWIII. It is not (always) of the conventional or visible kind. This war is being fought for the last market share of resources. Someone once said that war is always about resources. I live in Africa so we see this war being fought daily. I agree with the hypothesis that peace eventually brings self-destruction. Conflict brings out the best in humanity. We are not a peaceful nice species.