The constitutional convention on Europe's future finally packed its bags last week in Brussels. The dramatic change in Europe's demographic profile will weigh far more heavily on the continent's future than the institutional minutiae that have been preoccupying the conventioneers. Fertility rates across Europe are now so low that the continent's population is likely to drop markedly over the next 50 years. The United Nations (UN) predicts that the world's population will increase from just over 6 billion in 2000 to 8.9 billion by 2050. During the same period, however, the population of the 27 countries that should be members of the European Union (EU) by 2007 is predicted to fall by 6%, from 482m to 454m. Combine a shrinking population with rising life expectancy, and the economic and political consequences are alarming. Since pensions in Germany, France and Italy are paid out of current tax revenue, the obvious implication is that taxes will have to soar to fund the pretty generous pensions that Europeans have gotten used to. It is no accident that in the past year France, Austria, Italy and Germany have all experienced angry outbreaks of labor unrest, sparked by attempts to make their pension systems less generous. The tide of immigrants, legal and illegal, crossing the sea is an obvious reaction. So shouldn't Europe be more liberal about immigration, to redress its population imbalance? The inflow of immigrants is causing political strains, with anti-immigration politicians like France's Jean-Marie Le Pen, Italy's Umberto Bossi and the Netherlands' late Pim Fortuyn popping up all over Europe.