A few months ago, oncologist and bioethicist Ezekiel Emanuel had an essay in The Atlantic saying that all things considered, he would prefer to die at around age 75. He argued that he would rather clock out with all his powers intact than endure a sad, feeble decline.

The problem is, he would probably miss out on his happiest years. When researchers ask people to assess their own well-being, those in their 20s rate themselves highly. Then, there is a decline as people get sadder in middle age, bottoming out at around age 50. But then happiness levels shoot up - old people are happier than young people. The people who rate themselves most highly are those aged 82 to 85.

Psychologists who study this now famous U-curve tend to point out that old people are happier because of changes in the brain. For example, when you show people a crowd of faces, the young unconsciously tend to look at the threatening ones, but, for older people, attention gravitates towards the happy ones.

Older people are more relaxed, on average. They are spared some of the burden of thinking about the future. As a result, they get more pleasure out of the present in ordinary activities.

My problem with much of the research on happiness in old age is that it is so deterministic. It treats the ageing of emotional life the way you might treat the ageing of the body - as this biological, chemical and evolutionary process that happens to people.

I would rather think elder happiness is an accomplishment, not a condition - that people get better at living through effort, by mastering specific skills. I would like to think people get steadily better at handling life's challenges.

In middle age, they are confronted by stressful challenges they cannot control, like having teenage children. However, in old age, they have more control over the challenges and they get even better at addressing them.

Aristotle notes that being a good person is not mainly about learning moral rules and following them. It is about performing social roles well - being a good parent or teacher or lawyer or friend.

It's easy to think of some of the skills that some people get better at over time.

First, there's bifocalism, the ability to see the same situation from multiple perspectives.

Professor Anthony Kronman of Yale Law School once wrote: "Anyone who has worn bifocal lenses knows that it takes time to learn to shift smoothly between perspectives and to combine them in a single field of vision.

"The same is true of deliberation. It is difficult to be compassionate, and often just as difficult to be detached, but what is most difficult of all is to be both at once."

Only with experience can a person learn to view a fraught situation both close up, with emotional intensity, and far away, with detached perspective.

Then there's lightness, the ability to be at ease with the downsides of life. In their book, Lighter As We Go, Dr Jimmie Holland and Dr Mindy Greenstein argue that although older people lose memory, they also realise most setbacks are not the end of the world.

Anxiety is the biggest waste in life. If you know you will recover, you can save time and get on with it sooner.

"The ability to grow lighter as we go is a form of wisdom that entails learning how not to sweat the small stuff," the authors point out, "learning how not to be too invested in particular outcomes."

Then, there is the ability to balance tensions.

In Practical Wisdom, Professors Barry Schwartz and Kenneth Sharpe argue that performing many social roles means balancing competing demands.

A doctor has to be honest but also kind. A teacher has to instruct but also inspire. You cannot find the right balance in each context by memorising a rule book. This form of wisdom can be earned only by acquiring a repertoire of similar experiences.

Finally, experienced heads have an intuitive awareness of the landscape of reality, a feel for what other people are thinking and feeling, an instinct about how events will flow.

In The Wisdom Paradox, neuropsychologist Elkhonon Goldberg details the ways the brain declines with age: Cells die, mental operations slow. But a lifetime of intellectual effort can create empathy and pattern awareness.

"What I have lost with age in my capacity for hard mental work," Dr Goldberg writes, "I seem to have gained in my capacity for instantaneous, almost unfairly easy insight."

It's comforting to know that, for many, life gets happier with age. But it's more useful to know how individuals get better at doing the things they do.

The point of culture is to spread that wisdom from old to young; to put that thousand-year heart in a still-young body.

NEW YORK TIMES