WARREN BUFFETT, who on May 3rd hosts the folksy extravaganza that is Berkshire Hathaway’s annual shareholders’ meeting, is an icon of American capitalism (see article). At 83, he also epitomises a striking demographic trend: for highly skilled people to go on working well into what was once thought to be old age. Across the rich world, well-educated people increasingly work longer than the less-skilled. Some 65% of American men aged 62-74 with a professional degree are in the workforce, compared with 32% of men with only a high-school certificate. In the European Union the pattern is similar./.../