For years, the developed world experienced economic growth underpinned by population growth. Developing countries are now enjoying the population bonus of a bulge in working-age population, although they still have far lower resources per head to spend on health and education.

In comparison, developed countries are suffering from the population onus, an ageing population often supported by generous welfare states, funded by an unsustainable transfer of resources from the young and the poor to the older generation.

The most obvious solution, says Yasuchika Hasegawa, is to have more open immigration policies; but this is a discussion that many in developing nations are unwilling to have. Other solutions are equally unpalatable – raising taxes and retirement ages or reducing retirement benefits. Whatever we choose to do, developed and developing countries must work together to share technology and information, and there is no avoiding the immigration discussion.