Our mental acuity declines and our bodies fail us but, as renowned biologist Lewis Wolpert points out, old age also offers the possibility of great contentment

‘I feel it’s quite strange,” says Lewis Wolpert. “How could a 17-year-old like me be 81?”

Prof Wolpert is author of You're Looking Very Well: The Surprising Nature of Getting Old, just published by Faber and Faber.

It has long been said that old people see themselves as being at an age much younger than their chronological years. The 17-year-old Wolpert still plays tennis and rides a bicycle but is baffled by the 81-year-old Wolpert: “I can’t get over how slowly I walk in the streets. I still play tennis and ride my bicycle but when I am walking everybody walks faster than me,” he says.

His book takes both a human and scientific look at ageing. He is Emeritus Professor of biology as applied to medicine at University College London.

And sometimes that scientific approach pricks some rather silly current bubbles. I have heard otherwise sensible people suggest, for instance, that at age 70 we are going to live so long that this is the point at which we need to work out what our next career will be.

Not so. “To increase longevity significantly will be very difficult,” Prof Wolpert points out. “It’s about complexity of the cells; wear and tear of cells causes ageing.”

Measures to increase longevity would have to be taken “at the level of the embryo”. Then he chuckles: “The person who did it wouldn’t know if it worked because he wouldn’t live long enough.”

The embryonic stage might sound rather early for putting off old age, but there again, Wolpert’s book informs us with scientific detachment that our mental abilities peak at the age of 22 – yes, 22 – and we begin losing muscle from the age of 40.

No need to despair, though – happiness peaks at the age of 74, so it’s not all about mental abilities and muscle mass.

What can get in the way of happiness for some people, he suggests, is obligatory retirement. He misses his work. “I quite liked having my scientific research group,” he tells me. “On the other hand, retirement means I don’t have to write grant applications.”

In the book he puts it somewhat more starkly – after explaining that some aspects of his discipline, biology, have probably already moved ahead of him since he retired, he adds, “There are also, I regret, times when I wonder what the point of continuing to live really is.”

Asked about this, he does not expand on it beyond what he has already written in the book, but surely he is not alone in feeling this way about retirement – it’s just that it’s not usually talked about in that way.

One group of people who often don’t get to retire are grandparents. Just when they might be free to devote time to themselves, they are pressed into service as unpaid childminders.

Thankfully, Prof Wolpert has now come to the rescue with this: “There are also problems associated with the role of the caring grandparent. A study in London showed that children did better if they went to nursery school than if they were cared for by their grandparents. Their social skills at three years were worse and they had more behavioural problems already at nine months, though their vocabulary was better.”

Reluctant prospective grandparent-childminders should cut out that passage, frame it and hang it up inside the front door. And if they’re challenged on it, they can refer critics to page 62 of You’re Looking Very Well.

Then they can devote themselves to exercise and the Mediterranean diet (lots of fruit, vegetables, cereals and fish but, alas, low amounts of meat and poultry) as there is some evidence that the combination can reduce your risk of Alzheimer’s by about 60 per cent.

If they prefer, they can devote themselves to sex and crime instead, or as well. Prof Wolpert informs us that “the frequency of sexual activity, for those who are active, declines only slightly from the 50s to the early 70s, and . . . this activity continues into the 80s.”

“If the old have energy for sex,” he adds, “they also have sufficient energy for crime. In England and Wales, prisoners aged over 60 are the fastest growing age group in prison.”

He points out, though, that this is due to harsher sentencing policies and and that most old people in prison suffer from poor mental health.

There is, however, one area in which a sort of justice prevails: that is in the area of prejudice against the old.

“Young and middle-aged adults who endorse negative stereotypes about older people display high rates of strokes, heart attacks and other serious heart problems later in life, compared with ageing peers who view the elderly in generally positive ways,” he writes.

And he cites Yale University psychologist Becca Levy who found that “those who viewed ageing as a positive experience lived an average of seven years longer. This means that a positive image had a greater impact than not smoking or maintaining a healthy weight.”

We hear a great deal about the negative side of old age: income and mobility problems, long waits in AE, sometimes inadequate social services and so on.

But the overall picture is brighter than that. As mentioned earlier, happiness peaks in the mid-70s and, Prof Wolpert says, “There is good evidence that most people in their 70s and 80s are very contented with their lives.”

There’s just one caveat:

“You have got to be healthy and have enough money.”

You're Looking Very Well: The Surprising Nature of Getting Oldby Lewis Wolpert is published by Faber and Faber and costs £14.99