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Demography can often seem quite serious, but when you apply it to something a little more familiar, it becomes very interesting.

For example, "marriage" can also be discussed in terms of demography. Looking at the postwar population structure of Japan, it can be said that modern women have an overwhelming advantage in the marriage market. One of the reasons for this is the sex ratio at birth. This has not changed from ancient times to the present, and if the number of female births is 100, the number of male births is roughly 105, which is always constant regardless of ethnicity, country, or era. Therefore, structurally, there is inevitably a surplus of men. Another thing is that when we look at the average age at first marriage, in Japan, men are about two years older than women, so considering that the number of births has been declining for most of the postwar period, from the perspective of men, there are fewer women two years younger than them, which also puts women at an advantage.

When the 2010 lifetime unmarried rate was announced, researchers were very surprised by the figures. The lifetime unmarried rate refers to people who have never married at the age of 50, and it is double the rate for men at 20% and women at 10%. This is a figure that was unforeseen 20 years ago. One of the reasons for this is the remarriage rate. Men remarry more often than women, and those who marry once marry a second or third time. In other words, one popular man marries a second or third time, leaving unpopular men out, and the structure is such that they remain unmarried their whole lives. That's why I jokingly tell my students, "Men should never let go of a woman once they have her."

Japan is one of the countries with the lowest birthrates and the fastest aging population in the world, and its population decline will accelerate in the future. The population, which was 127.77 million in 2005, is expected to decrease by more than 30% to 86.74 million in 2060, 55 years from now. What kind of society awaits us in such a future? Let's first look at Japan's past from the perspective of population.

After World War II, the first baby boom occurred. People born between 1947 and 1949 are called the baby boomer generation, but let's look at them as a cohort (group of people born at the same time).

For example, people born between 1945 and 1949, including the baby boomers born between 1947 and 1949, are called the "1945-49 cohort." One of the features of demography is the analysis of groups by year of birth. If we look at the figure on the right, "Number of inter-prefectural migrations by metropolitan and non-metropolitan area type," for 1960 to 1969, 15 to 20 years after the 1945-49 cohort became workers, we can see that a very large number of people migrated from non-metropolitan areas to metropolitan areas. These people became abundant workers in heavy, large-scale industries such as steel and shipbuilding, and led Japan to high economic growth.

However, between 1975 and 1979, this stopped completely. This was called the "U-turn era," and was said to be a phenomenon caused by people returning from metropolitan areas to their hometowns, but in fact, this is slightly different. It wasn't that more people were returning, but rather that fewer people were leaving. As you can see from the graph in the upper right, there was a sudden drop in the number of people moving from non-metropolitan areas to metropolitan areas.

The reason why fewer people are moving from non-metropolitan areas to metropolitan areas is because the number of births has been falling significantly since the 1950s after the end of the first baby boom, and the overall number of people moving out has decreased to begin with. It can be said that the disparity in population size between the baby boomer generation and the next generation caused this social phenomenon, which we call the "cohort effect." From an economic perspective, the theory is that population movement occurred because of rapid economic growth, and this is what is often said on the streets. I do not deny this, but from the perspective of a demographer, it can be said that rapid economic growth occurred precisely because there was an abundant labor force. It can also be said that economic phenomena and population have a synergistic (interactive) effect.

Let's look again at the graph "Number of inter-prefectural migrations by metropolitan and non-metropolitan area type." Around 1993, a similar reversal phenomenon to that seen between 1975 and 1979 occurred again, and this is related to the baby boomer juniors. Baby boomer juniors refer to people born between 1971 and 1974, but if we look at the cohort born between 1971 and 1975, which includes these juniors, they are around the time they turn 20. They are about the age when they would leave their parents' homes, but the baby boomer juniors are the children of the baby boomer generation and were originally born in metropolitan areas. This is why the number of people migrating from non-metropolitan areas to metropolitan areas has decreased.

Research is still in progress on this issue, so it is difficult to say for sure, but the baby boomers born in metropolitan areas have no need to move because there are universities and job opportunities in the same area. This means there is no reason to leave their parents' home, and the number of parasite singles is increasing. Everyone wants to be happy. Rather than getting married and becoming poorer financially than before, people want to maintain their current standard of living, and the unmarried rate is increasing. This is thought to be the beginning of a trend toward later marriage and non-marriage, which leads to a declining birthrate and a rapidly aging population, which is one of the demographic issues.

When it comes to the issue of aging, many people may think of it as something that only applies to depopulated areas rather than large cities. It is true that the aging rate is higher in depopulated areas, but I think that from now on, aging will be brought into greater focus as an issue for metropolitan areas. This is because, from now until the middle of the 21st century, the rate at which the aging rate in metropolitan areas is increasing will often exceed that of non-metropolitan areas.

So why is the aging of the population in metropolitan areas progressing so quickly? Again, the baby boomer generation is cited as a cause. If they were evenly distributed across the country, there would be no regional differences, but they live in large metropolitan areas. To be precise, all generations are biased towards metropolitan areas, but the bias for the baby boomer generation is greater than for other generations. This generation is becoming elderly one after another at this very moment. In particular, in large housing complexes in the suburbs of metropolitan areas that were built during the period of high economic growth, the number of residents suddenly aging at a time is increasing. In collective housing such as complexes, the generation of people who first moved in is biased towards a certain age group (mainly in their 30s), so if those people continue to live there, at some point the majority of the residents will become elderly, just like in a game of Othello. And many of these residents are the baby boomer generation. Moreover, such collective housing is significantly aging and does not support barrier-free access. It is four or five stories tall and does not have elevators. Even if their legs become weak, they have no choice but to go up and down the stairs. These problems associated with aging will increase at a rapid pace in the future.

In any case, the aging of society will undoubtedly become more serious in the future. However, there is a way to lower the aging rate, which is currently about 25% (2013), overnight. Do you know how to do it? The answer is to change the definition of the elderly. Usually, people aged 65 or older are considered elderly, but if this age standard is changed to 75 or older, the aging rate will drop to about half at once. This is not a joke. If you take a survey of people aged 65 to 74, you will find that many of them are healthy and have a desire to work. In other words, with the average life expectancy increasing today, it is no longer very reasonable to treat the early elderly as the same "elderly" as people aged 75 or older.

However, the speed of aging cannot be solved overnight. Even if you change the definition, some things are fast. The problem is that many of our social systems, both hard and soft, are built on the basis of population structure. The best example is pensions, as well as elderly care facilities and the nursing care insurance system. However, since this is not something that can be designed immediately, we need to pay attention to metropolitan areas where the speed of aging is fast.

It seems that systems have yet to catch up with these issues surrounding the aging population, but when problems arise, appropriate solutions or business opportunities also emerge.

For example, in response to the aforementioned problem of aging housing complexes, the Urban Renaissance Agency has taken an interesting and successful approach: They renovated several buildings in an old housing complex in Hino City, Tokyo, into stylish rental housing for the younger generation, and developed various facilities around the complex so that both new and old residents could gather.

As a result, people of different generations have started to actively interact with each other within the complex. Also, as an example of former public housing, it is interesting to note that over 20 buildings in the area that was developed earliest in Tama New Town have been replaced by a private developer into a group of seven high-rise apartment buildings.

What makes this case interesting is that the previous residents were able to move into the new apartments with almost no additional costs. This was because the surplus in the floor area ratio (a standard under the Building Standards Act that defines how much floor area a building can have in relation to the land area) was used to significantly increase the total number of units, and the additional units were sold to raise the funds for the reconstruction. In this way, the problems of the old housing complex, such as no elevators and no barrier-free access, were completely solved.

Japan's population will decrease by hundreds of thousands per year from now on. We are entering an era opposite to the "demographic bonus" I mentioned earlier. If the population decreases and productivity per capita remains the same, it is easy to predict that the Japanese economy will shrink in the future. Demographers tend to be pessimistic about such a future, but I sometimes change my tune to be an optimist. The problems of aging and declining labor force are based on classifications decided by humans. Just like the definition of elderly people mentioned earlier, humans can remake it again. It is inevitable that the aging population will progress to a certain extent. I think it is important to have a new idea of accepting aging and creating a good society even in spite of it.

(Published in 2014)