The Institute for Health Metrics and Evaluation at the University of Washington recently issued projections for longevity by country in 2050. Among the top 20 for living to a ripe old age are rich ones like Switzerland and Singapore. But a geographic cluster of relatively poorer countries are also conducive to longer lives: Spain, Italy, France and Portugal.

"Health and long life correlate unsurprisingly with GDP per capita. Why does southern Europe outperform the usual link between wealth and health, making the average lifespan in Spain (85.5 years in 2050) longer than that of the average Dane (83.5)?"

• sunshine
• alcohol consumption
• social life
• Mediterranean diet
• physical activity

Besides, researchers find that today’s Mediterraneans do not stick to their namesake diet. Plazas in Spain are full of people eating fried fish and salted ham, washed down with beer at hours some might consider unseemly. Spaniards drink more booze and smoke slightly more than the European average, and are among Europe’s biggest cocaine users.

Diets today increasingly include Western processed foods, but “cultural inertia” keeps them somewhat healthier, says Mr Buettner.

That shepherding past points to another factor: movement. Spaniards lead western Europe in steps per day at 5,936, according to a study from 2017. (Italy, France and Portugal are less impressive.) The study found that countries with “activity inequality”—a few prolific walkers but many couch potatoes, as in America and Saudi Arabia—had the highest obesity rates.