It must be the chocolate...or the cheese...or the Alpine air...or the fierce independence. People in Switzerland are more likely to make it to 100 than people in any other European country. Researchers in France and in Lausanne, on the shores of Lake Geneva, looked at patterns of age in Switzerland.

What the researchers wanted to know: How is Switzerland aging?

What they did: The researchers used data from censuses, carried out once a decade sine 1860, and from annual estimates of population.

What they found: Between 1876 and 2001, life expectancy at birth nearly doubled, from 40ish to close to 80. As in much of the world, life expectancy dipped around the tip of the 1918 flu epidemic, but Switzerland stayed out of World War II, and life expectancy continued to increase through the 1940s and through the present. Switzerland has also kept track of the maximum age at death; while this was around 102 in the late 1900's, it's up to 110 now. In 1860, there were 10 people age 100 or older; at the time of the last census, there were 796. Swiss women, following the usual pattern, live longer than men.

What the study means to you: Since the researchers didn't have long-term data on sanitation, disease, and so on, they don't really know why people are living so long. Switzerland's population of old folks is right up there with Japan's. More studies might be able to tell us why exactly life expectancy is increasing so rapidly.

Caveats: The researchers say Switzerland's data on old people probably isn't perfect.

Find out more: Wouldn't you like to know the weather in Switzerland right now? www.meteoswiss.ch

Read the article: Robine, J.-M. and F. Paccaud. "Nonagenarians and centenarians in Switzerland, 1860-2001: A Demographic Analysis." Journal of Epidemiology and Community Health. January 2005, Vol. 59, pp. 31-37.

Abstract online: http://jech.bmjjournals.com