As the number of births falls below replacement level in many countries, the developed world is living with the fear of demographic ageing and population decline. With one of the world's lowest fertility rates - 1.3 children per woman - and the highest life expectancy, Japan is an extreme illustration of this trend. Analysing the latest Japanese population projections, Jacques Véron explains the inevitable and possible consequences for the country's demographic future.

Under the medium variant of the demographic projections issued in 2006 by the National Institute of Population and Social Security Research in Japan, the Japanese population is set to fall more than 30 million by 2050. Rapid population ageing will also occur due to increasing life expectancy - already the world's longest - and lowest-low fertility: 1.3 children per woman on average in 2006. The economically active population will continue to decline and the dependency ratio will rise dramatically as the proportion of over-65s increases. A limited upturn in fertility, measured opening of the Japanese borders or marginal behavioural changes in the working population are unlikely to have much impact on these projected trends.

• Sustained low fertilityand the world's highest life expectancy

• Fewer extended families, more people living alone

• Radical changes in the age structureand a smaller labour force

• Are these changes inevitable?