Japan is the case everyone thinks they understand: an ageing country whose population has stopped growing because of a low birth rate. That much is correct — by 2065 the book puts Japan's population at 86 million, a drop of 40 million in 40 years, and sustaining current total GDP would require productivity per worker to rise by 0.9% a year for the entire period. Japan's rate for the last decade was 0.7%, so it might be achievable. So not an economic disaster. Furthermore, GDP per capita — the true measure of affluence — grows steadily, at 0.9% per annum, under that assumption.
What is less well known is that the society's age structure barely shifts over that horizon: society is reduced in size but not disrupted in structure. The ratio of workers to non-workers is relatively unchanged over 40 years.
Japan is not alone. Most developed countries face population decline from falling births even allowing for high immigration — it is a matter of degree, and rarely as smoothly managed as Japan's. China and Western Europe, for instance, are shifting decisively toward an older population (China because of birth policy, Europe as a result of earlier adult migrant waves), raising real questions about how they will support an aged market of unprecedented scale.
At the other extreme are Southern Africa (not just South Africa), West Africa and East Africa. They are projected, with real confidence, to more than double in total population — from 1.1 billion to 2.6 billion by 2065. The number needing to be employed is projected to rise from 471 million to 1,160 million, meaning some 689 million additional jobs must be created. Some will be domestic; much of the rest depends on export demand from consumer economies that are themselves facing flat or slowing population growth, and perhaps consumption spending.
India sits in the middle, neither contracting nor expanding rapidly — but its long-vaunted 'demographic dividend' is now running out. Growth will become almost entirely a function of productivity per worker rather than workforce growth, fortunately just as the effects of India's move to universal education, introduced in 2010, begin to reach the labour force. Whether that lift arrives fast enough — and what happens to India's consumer segments in the meantime, since it is no longer the child-heavy market it once was — is one of the book's central questions.
Additionally, for many developing countries, there is the question of who is in the workforce. Historical gender norms are likely to change (as much a function of increased access to education as anything else), and that will affect the size and growth of the potential number of people seeking work. Will there be enough demand for additional output, and hence workers, as demographic trends indicate is needed? AI and robotics are an issue here.
The book also corrects a common misreading of falling birth rates. In countries such as China, the birth rate itself — births per 1,000 women aged 15 to 49 — has actually stabilised, at around 35. What keeps falling is the number of women of childbearing age: in China, from 310 million in 2025 to a projected 188 million by 2065. Because everyone who will be aged 15 to 49 in 2040 is already alive today, that decline is almost certain through 2040 — no policy change will alter it.
On productivity, education is the clearest driver — but the dynamic has changed. Countries with well-educated workforces are close to the ceiling of what education alone can add. After all, you can only have so many PhDs in one office! (Just one is sufficient to make the coffee.) For countries still catching up, an upgraded education system takes at least 25 years to fully raise productivity. India's introduction of compulsory education in 2010 is only reaching the female workforce now, and it will be another 10 years before they are a large enough proportion to alter the capability of the workforce. Meanwhile, the sheer scale of the challenge in parts of Africa is difficult to grasp: some regions must add well over 2,000 classrooms a day, every day, for the next 40 years, just to keep pace with a still-expanding school-age population.
