A few years ago Wired, the technology magazine, ran a regular feature called “Japanese schoolgirl watch”. The concept was not as dubious as it sounds. The idea was simply that the schoolgirls of Japan are technological trendsetters and that the gadgets they adopt today will go global tomorrow.

These days, however, Japan is also a global trendsetter in other, more troubling ways. If the policy makers of Europe and North America want a sense of the social, economic and strategic challenges they may face in the coming years, they should visit Japan, as I did last week.

One idea might be to start a “Japanese granny watch”, since the country offers a sobering lesson in the consequences of longer life expectancy and lower rates of childbirth. Both trends are particularly extreme in Japan, but replicated – to some degree – in most rich nations. Japan’s population began to shrink in 2010. It is projected to fall from 127m today to 86.7m by 2060, when 40 per cent of the population could be over 65. As a result “care robots” – which can do things such as helping granny off the lavatory, as well as engaging in simple conversations about the weather – are at the centre of a flourishing industry.