The Japanese have known it was coming for years, but it arrived sooner than anyone expected. The Japanese population has gone into absolute decline. There will be at least 60,000 fewer Japanese at the end of this year than a year earlier, and the decline will accelerate.
It's the same elsewhere in East Asia. The National Statistical Office in Seoul says South Korea's fertility rate - the number of babies the average woman has in a lifetime - has plummeted to 1.16, even lower than Japan.
China looks better at 1.7, but that is deceptive because there is a 15 per cent surplus of boys over girls in the youngest population groups. All these countries' populations will fall steeply over the next generation.
The obvious explanation is that the East Asian countries, as they educate their people and turn into fully developed societies, are simply following the well-beaten path first travelled by the European countries.
Italy, after all, has a total fertility rate of only 1.4, and Russia is down to 1.3. If such trends persist, there will 15 million fewer Italians by mid-century and 40 million fewer Russians. But the obvious explanation is probably wrong, because not all developed countries have collapsing birth rates.
In countries that attract large numbers of immigrants - including the United States, Canada and Australia - the populations will remain stable or grow, but that situation is not relevant to East Asia.
China, Japan or Korea could easily attract immigrants in large numbers, but they could not integrate them - their citizens simply cannot believe that someone from the Philippines, Iran or Ethiopia could ever become a full member of the host society.
Some European countries are holding their populations without mass immigration. The average fertility rate in France, to pick the most striking example, is 1.9. That is not quite enough in itself to keep the population stable because the "replacement" rate is 2.2, but it is close enough to mean that a relatively small flow of migrants guarantees population growth.
The French population, now close to 60 million, is forecast by the United Nations to become 63.5 million in 2025.
So what are the French doing right? France and Japan are both fully industrialised and highly urbanised, with generous social services, and have very well-educated populations.
They are both places where it is very expensive to have children. And both countries have experienced extreme fluctuations in their birth rates in response to changing conditions.
Japan's population almost doubled in the half-century after 1945, from 70 to 125 million. If the present trend persists, it will be back to 70 million before the end of this century.
France's population, by contrast, was already 40 million in 1840, but it then stopped growing for 100 years, mainly because it remained a largely rural country and generations of farmers limited their children to avoid having to divide their farms.
But rapid post-war urbanisation ended their obsession with land, and in the past 50 years the population has grown from 40 to 60 million. It is still growing, albeit slowly. Why?
The biggest difference between France and Japan is the status of women. Japanese women have a low status in the family. And despite the occasional female high-flyer they have an even lower status in the workforce, which they are generally expected to leave after they marry.
As a result, they have in effect gone on strike - the average age of Japanese women at marriage is going up by several months each year, and the birth rate has collapsed.
In France, by contrast, the traditional male-dominated family is all but dead and almost half of all French children are born "out of wedlock" - but informal new styles of family living give women more control over their lives while still providing secure environments for most children.
And the main thing women do with their freedom is to stay in the workforce: 80 per cent of French women between 24 and 49 work, the highest rate in the EU.
It's not just about money, it's about independence and satisfaction with life. The French Government helps women with free child-care, subsidised holiday camps during the school holidays, and tax breaks and family allowances for bigger families.
Other countries do the same, but with much less impact on the birth rate. The three-child family is still the norm among the French middle-class because French women do not feel they must choose between motherhood and a life outside the house.
There are no immediately useful lessons in this for East Asian societies, because changing popular attitudes on gender roles takes decades or generations.
For the many countries that are still in the "demographic transition" and working to get their birth rates down to 3.0 or even 4.0, it is bound to seem a distant and hypothetical problem.
But there is a lesson for everybody here. The lesson is this: if you don't want your country's population to fluctuate like a yo-yo on a 50-year string, pay attention to women's status inside and outside the family.
* Gwynne Dyer is a London-based independent journalist whose articles are published in 45 countries.
<EM>Gwynne Dyer:</EM> Status sums up growth
AdvertisementAdvertise with NZME.