Vietnam is getting old before it gets rich

AS DAWN BREAKS in Hanoi the botanical gardens start to fill up. Hundreds of old people come every morning to exercise before the tropical heat makes sport unbearable. Groups of fitness enthusiasts proliferate. Elderly ladies in floral silks do tai chi in a courtyard. In the shade of a tall tree, dozens of ballroom dancers sway to samba music. Others work up a sweat on an outdoor exercise-machine. Tho, an 83-year-old with a neat white moustache, says he comes to walk round the lake every day, rain or shine.

In the next few decades the gardens will become busier still. Vietnam has a median age of only 26. But it is greying fast. Over-60s make up 12% of the population, a share that is forecast to jump to 21% by 2040, one of the quickest increases in the world (see chart). That is partly because life expectancy has increased from 60 years in 1970 to 76 today, thanks to rising incomes. Growing prosperity has also helped bring down the...