There are other possible explanations. Maybe the sight of contemporaries keeling over infuses survivors with a determination to make the most of their remaining years. Maybe people come to accept their strengths and weaknesses, give up hoping to become chief executive or have a picture shown in the Royal Academy, and learn to be satisfied as assistant branch manager, with their watercolour on display at the church fete. “Being an old maid”, says one of the characters in a story by Edna Ferber, an (unmarried) American novelist, was “like death by drowning—a really delightful sensation when you ceased struggling.” Perhaps acceptance of ageing itself is a source of relief. “How pleasant is the day”, observed William James, an American philosopher, “when we give up striving to be young—or slender.”
Whatever the causes of the U-bend, it has consequences beyond the emotional. Happiness doesn't just make people happy—it also makes them healthier. John Weinman, professor of psychiatry at King's College London, monitored the stress levels of a group of volunteers and then inflicted small wounds on them. The wounds of the least stressed healed twice as fast as those of the most stressed. At Carnegie Mellon University in Pittsburgh, Sheldon Cohen infected people with cold and flu viruses. He found that happier types were less likely to catch the virus, and showed fewer symptoms of illness when they did. So although old people tend to be less healthy than younger ones, their cheerfulness may help counteract their crumbliness.