Women are rejecting marriage in Asia. The social implications are serious.

You have no idea what the relevant numbers are. The estimated loss of life during the Crusades ranges from 3-10 million lives. Current estimates place the Russian loss of life alone from WWII at 19.5 million.

>First note that the childless already massively subsidize parents through taxes that pay for education. Also note that I am considering replacement levels of fertility desirable.

This isn't as simple as that. The tax revenue used for education in Texas comes from property taxes. The majority of that is from homeowners. The overwhelming majority of homeowners have or had children in the home at some point. Aside from those facts, would you like to live in a society where the children were not educated? I think you would find that the reduction in crime and the boost to the cheap labor force would be worth the investment.

The most important point this should make is: all of these things are fabulously complicated and interrelated.

Seems to me that the article missed the most central point. Let's start with a little, simple, relevant background:

(1) In the past, e.g., in tribal or agricultural communities, women had children whether they really 'wanted' to or not.

(2) Now in more industrialized countries, a significant fraction of women have some options. Some women still have children but some women do not want to have children and do not.

(3) The change in number of children per woman is a 900 pound gorilla in the room: The article mentioned numbers under 2 children per women with a rate a low as 1 child per woman. There is some recent data that Finland is at 1.5 children per woman.

Of course, for any rate much under 2, each 20 years or so the population will be going down significantly. "Get your old houses, furniture, dishes, baby clothes, etc. cheap, cheap, cheap!".

So, net, heavily women who don't want to have children won't. These women will be 'weak, sick, dead limbs on the tree' and will be pruning their genes from the tree. What will be left are women who, given the choice, actually, effectively WANT to have children.

The big point: After a few such generations, we will be left with a much smaller population with many fewer women but nearly all of whom WANT to have children. Then the population will start growing again.

One more big, surprising point: We are now, in much of the world, in the most rapid change in the gene pool of the last 40,000 or so years.

Where did the 40,000 come from? Humans walked out of Africa back there somewhere. At one point, ballpark 40,000 years ago, they reached, say, India. One branch went west to Western Europe, and another branch went east to China and Japan. Mostly the two branches haven't much mixed since then.

Okay, at the common branch, ballpark 40,000 years ago, what were women like? Well, take women from Japan and women from Western Europe. Take some 'characteristic' in common, say, desire of a major fraction of the women, given an economic opportunity, not to have children. Now, start in either Japan or Western Europe and count genetic 'changes' on this 'characteristic' going backwards in the tree to the common branch, about 40,000 years ago, and, then, continuing to count changes, going forward in the other branch of the tree to the present.

So, if on this characteristic the women in Japan and Western Europe are close, that is, have few changes, then on this characteristic the common ancestor 40,000 years ago has still fewer, that is, is closer to the women in both Japan and Western Europe than they are to each other.

Net, since a significant fraction of women in both Japan and Western Europe will, given an economic opportunity, choose not to have children, that is, these women are close to each other, both are still closer to their common ancestor 40,000 years ago. So, for 40,000 years, many women had children not really because they 'wanted' to but because of economic necessity.

So, now that women who don't really want to have children are being pruned from the tree, we are, on this characteristic, in the most rapid change in the human gene pool of the past 40,000 years. And, the change is VERY rapid, should have a huge effect in just a few generations, say, just 100 years, which on the scale of 40,000 years, is FAST.

Have you read "The Fates of Nations" by Paul Colinvaux? It's a fascinating - and disturbing - book, covering the exact topic you are talking about.

But where Colinvaux and myself would disagree with you, is the direction of the cause and effect.

My interpretation is that a society starts off warlike. At some point it either conquers, or is conquered by its neighbors. Once the empire is at its natural borders, war no longer provides a good economic rate of return. People avoid the army and instead go into trade or farming. The imperial peace provides a stable base for commerce and industry. People become rich. As they grow rich, and as the need for martial valor declines, people become more decadent. They spend more on luxuries, they have less need for children. Thus both a decline in fertility and a decline in aggressiveness are symptoms of the underlying cause (war no longer being necessary for survival, and war no longer providing a good rate of return). Eventually though, on the borders of the empire some new, highly fertile, highly aggressive population arises. Meanwhile the old growth civilization has long lost its martial prowess, and each individual resident faces a game theory optimum of continuing the decadence, rather than face the rigors of a martial life. Thus the bordering tribe eventually is strong enough to invade, the old civilization falls, and the cycles of history continue.

"Humanity grows exponentially, food production grows linearly" has not been debunked. People have starved in the last few decades, and we barely managed to avoid a widespread catastrophe through a big one-time upgrade to the best farming techniques known. How many other improvements are left before we reach biology's productivity limits? How long until we run low on natural gas to make fertilizer, having long since mined the pre-existing fertility from the soil?