As life expectancy grows and birth rates slump across the EU, around one third of the bloc's population could be over the age of 65 by 2050, a social shift with the potential to transform the lives of Europeans.
Only three years ago, just 16.5 percent of the inhabitants of the European Union's current 27 member states were over 65.
The proportion is expected to grow to 18 percent by 2010, 25 percent by 2030 and 30 percent by 2050, according to recent forecasts from the EU's Eurostat data agency.
The number of European residents over 65 surpassed those under 15 at the beginning of the decade.
Currently, the EU's "oldest" members are Germany and Italy, where the proportion of over 65s is 20 percent.
Worldwide, only Japan has so far been confronted with a similar demographic phenomenon: around a quarter its 127 million people are already over 65, and the proportion is set to grow.
The scale is greater in the EU, which has a far larger population -- currently 495 million -- and a vaster geographical spread.
From 1990 to 2005, the average European's life expectancy rose by around two years.
After hitting 65, an average man in the EU is likely to live another 17 years, and a woman another 20.
In parallel, birth rates have plunged.
The average EU fertility rate -- the hypothetical number of babies per woman of child-bearing age -- has fallen to 1.5 from 1.6 in 1990.
Demographers say that just over two children per woman are required to keep a population from shrinking, without counting immigration.
The most marked slump has been in countries from the former communist bloc, 10 of which have joined the EU since 2004.
Fertility rates were around two when their regimes crumbled in 1989.
Today they are at record lows -- in Slovakia, for example, the rate was 1.2 in 2006 -- as many women put off having children.
"The postponement of marriage and child-bearing became a very rational strategy in the changed economic and social conditions", as the free market replaced communism, said Michaela Potancokova of Slovakia's national statistics office.
According to Irena Kotowska, a demographer at Poland's Warsaw School of Economics, the EU's former communist countries are simply following a trend which began in the 1960s in Scandinavia before reaching other western and then southern European countries.
Across the EU, the number of working women has grown, providing greater financial independence which has enabled a shift from the traditional model of a wife raising children supported by a husband's income.
European women also study longer and often focus on developing their career before having children.
In 2003 the average age of a woman having her first child was 28, two years older than in 1990.
Experts say falling birth rates can be stemmed, provided European countries give would-be parents a way to balance their professional and family lives thanks to creches and kindergartens, as in France, or generous paid leave for mothers and fathers, the path chosen by Sweden.
Some EU members have opted for immigration to shore up the younger generation.
Spain, for example, has drawn in millions of young migrants, many of them from Latin America.
Most demographers, however, say Europe will just have to get used to a new age structure and learn to live differently.
Governments will need to manage public finances better to ensure pension systems and health services are not undermined because there are fewer younger workers to pay social security contributions, and also accept the growing political clout of the elderly.
According to EU Social Affairs Commissioner Vladimir Spidla, Europeans should stop looking at aging as a costly burden and "seize the opportunity of new markets linked to the news of an aging population".
The term "Silver economy" is becoming a new buzzword, referring to services and products targeted at older consumers.