The Germans have a saying: "Happy like God in France". A modern version might be "Happy like a wrinkly in France".
The explosion in the numbers of very elderly French is something of a mystery to the French themselves. And a bit of a worry. By mid-century, at the current rate, there could be 170,000 French centenarians.
The best guess of French researchers is that there is something in the French climate and diet which is conducive to long life. But climate and diet have been roughly the same for years. The proliferation of French centenarians, three quarters of them women, is explained by advances in medical treatment, and the generally lavish provision of good-quality healthcare since the 1940s.
A decade ago, American researchers discovered something that they called the "French Paradox". French people lived longer and were healthier even though they consumed many things – especially large quantities of red wine – which were supposed to inflict bodily harm.
The true paradox of French longevity is more complex than that. It is a series of interlocking paradoxes.
First, there are regional differences. Expectation of life is higher in the south of France than in the north, and especially high in the south-west. If you truly wish to live to be 100, you could try the red wine, olive oil, poultry, fish and haricots of the typical French south-western diet.
Secondly, longevity is supposed to be a sign of contentment. Yet polls and anecdotal evidence suggest the French are a naturally cantankerous and discontented people.
Finally,the French are no longer eating and drinking like the French. Medical researchers worry they have moved to a more Anglo-Saxon diet: more fat, more processed foods, more beer.
Perhaps there will not be a great great granny-boom in mid-century France after all.