Nowadays we do everything later, be it prancing shamelessly across a stage in front of thousands, a la Sir Michael Jagger, or conquering Mount Everest for a second time, like 73-year-old Tamae Watanabe. As we live longer, humanity is increasingly refusing to sit back, put its feet up and settle for a quiet old age.
Nowhere is this phenomenon of age aping youth more noticeable than in the field of divorce. So-called ''silver separation'', the parting of couples in their sixties after as many as 40 years of marriage, is on the rise, bucking the general downward trend in divorce.
The actress Diana Quick was 61 when she separated from her actor partner, Bill Nighy, after 27 years. As she said in an interview with The Daily Telegraph this week: "There are far more couples splitting up in their sixties now and one reason is that they can. Economically, they have more independence."
The former US vice-president Al Gore, 64, separated from his wife Tipper in 2010, after 40 years of marriage. And the actor Arnold Schwarzenegger, 65, separated last year from Maria Shriver, his wife of 25 years. "People feel that if they don't make a break for it, they're never going to do it," says Geraldine Bedell, editor of the website Gransnet.
The statistics bear her out. Three years ago, 11,500 people in England and Wales aged over 60 were granted a divorce. In 2010, the most recent year for which figures are available, that rose to almost 14,600. While only five per cent of the total, over-sixties divorce continues to rise, even as overall divorce rates decline to a level last seen in the 1970s. The reasons are varied, but for many disillusioned spouses, the basic answer is because they can.
As the young struggle to put a toe on the housing ladder, middle-class retired couples often occupy properties valuable enough to provide man and ex-wife with the means to ''start again''. Added to that is the baby boomer's sense of entitlement, the belief cultivated in the 1960s and 1970s that life is there to be enjoyed rather than endured. With the children grown up and gone, what is there to stop them?
"This is going to become more common - it's inevitable," says Ros Altmann, director-general of the over-fifties lifestyle company Saga. "Many men and women who hit their sixties still have parents alive and realise that it's not all over. They have lots of life ahead of them, and think, 'What do I want?'"
Sue Plumtree, from Richmond, Surrey, left her husband in 2004, just as she was about to turn 60. She now works as a life coach. "I was married for 37 years when I finally decided I deserved better," she says. "It's not that I didn't love him any more, it was just time for a better life, and it was the best thing that I've ever done.
"I can't tell you how exciting your sixties are. I'm doing work I'm passionate about; I give talks and I share what I've learnt. I have a purpose that I didn't have before. I was in an unhappy relationship and didn't realise I had the power to change things."
This striving for ''fulfilment'' in later life is a by-product of longevity. "Some of those marriages that in previous generations would have ended in death now end in divorce," says Betsey Stevenson of the University of Pennsylvania, who has made a study of marriage and divorce. "You can't divorce if you're dead."
The American sociologist Susan Brown divides the evolution of wedlock into distinct periods. First, there was the ''institutional phase'', in which marriage was regarded as an essentially economic arrangement. This was succeeded, after the Second World War, by the ''companionate phase'', in which men and women were judged by their conventional roles as bread-winner and housewife. Then, some time in the 1970s, a new epoch in male-female relations dawned - the ''individualised phase''. This is all about personal need - ''me-ness'' - and a traditional marriage lasting four decades, involving Bert having his potatoes cooked just so, is unlikely to meet its demanding criteria, particularly for women.
"Among those women who have left their husbands, there is often a sense that the men never tried hard enough, that they expected to be looked after," says Ms Bedell. "Retirement is often a crunch point for couples. A lot of women aged over 50 feel they have subsumed themselves in order to look after a family, to care for children who have fled the nest. Now, they feel, is the time to assert their identity, to please themselves and stop putting up with childish demands."
Liberation from oppressive men-folk may suit some women, but for many others divorce carries with it enormous hurt and vulnerability, stemming as it often can from male infidelity.
"Far more women in their sixties are now single, and sometimes it isn't their choice," says Ms Altmann. "Most women would have been expecting their husband to provide a pension for them, for example, and suddenly he's not there.
"Also, people simply no longer feel old at 60, and realise they have years of life ahead of them. Nowadays, when you hit your sixties, it can be the start of a new life. Maybe you're stopping work, maybe the children are leaving home, and you suddenly think: 'What next?'
"Maybe the mid-life crisis is happening a bit later. Men reach their sixties and think, 'I want something more', in the way that men in their forties used to. Perhaps everything is happening later, as people live longer and have children later."
Ms Altmann has seen the unhappiness that can follow a late and unexpected divorce. "I have a friend who never worked, as she was caring for others. Then her husband decided he wanted a younger model. He walked out and she is finding it so difficult to earn money; she has lost the pension support, too. She thought they would be together forever. Lots of women are in a similar situation."
Social isolation and poverty are common outcomes of divorce, together with the misery of litigation. Jo Edwards, of Manches, a firm of solicitors, specialises in ''high net worth'' divorce cases. "I've seen a marked increase in the number of older couples going through divorce," she says. "In terms of my caseload at the moment, probably a third involve marriages of 20 years or more. With an older couple, it's about disentangling two lifetimes' worth of assets, and possibly debts. One also has to plan for retirement and divide pensions."
Clients often voice more personal concerns. "Women in particular are worried about whether they will meet anyone else. It's a real fear for people over the age of 60."
There are unexpected consequences to the growth of the grey dating market, too. Older people, no longer concerned about unwanted pregnancy, often fail to use barrier contraception, resulting in a greater incidence of sexually transmitted disease.
But for Sue Plumtree, late divorce has been a form of liberation. Her husband, 69 when the divorce took place, initially greeted his new state with "anger, bitterness and hurt", but has since undergone his own form of reinvention. "Now he lives overseas and has become an environmental campaigner," she says. "I'm very proud of him. He is living the life he was supposed to have. It fulfils him, I know that.
"People love, but it doesn't always work for the other person. I had a list as long as my arm of everything he did or said that was wrong, as evidence that it was his fault. It took me some years to see my contribution, and that wasn't an easy thing to do. I hurt him in all kinds of ways, wanted him to be different. I nagged him and wanted to control him.
"The great thing about knowing this is that by recognising my contribution, I am empowered. If and when I fall in love again, I will know what not to do."