bbc.com / “Between the ages of 100 and 105, I published four articles,” says the elderly man sitting opposite me. Now 106, Bill Frankland is probably the oldest active doctor on the planet. Though I’m meeting him on a bright, cloudless Saturday morning, he is happily settled in his office in London, dressed in a suit and tie, surrounded by a sea of academic papers.

As of 2015 there were are around 451,000 living centenarians, and this number is set to increase eightfold over the next three decades

Frankland first trained as a doctor in the 1930s. During his long and illustrious career, he has become the world’s foremost authority on allergy. He worked with the Nobel Prize-winning discoverer of antibiotics, Alexander Fleming, and was once called out to Iraq to treat dictator Saddam Hussein.

Though the rules at the time meant he had to retire officially at 65, there was no question of giving up work and he has been working in a voluntary capacity ever since. “What would I do otherwise?” he explains. His latest project will be out soon. “I thought ‘I must write another article when I’m 106’. And actually it’s scribbled out already. I’ve more or less finished it.”

View image of (Credit: Zaria Gorvett)

Needless to say, Frankland’s attitude is unusual. Most people imagine their later years as an extended holiday – a chance to swap desk chairs for arm chairs and start taking afternoon naps. But this might not be quite how things pan out in the future.

There’s a sizeable gap between the amount that most people are saving towards their retirement, and the amount that they’re likely to need. It’s growing every day. According to a recent report by the World Economic Forum (WEF), people living in some of the world’s largest economies – the US, UK, Japan, Netherlands, Canada, Australia, China and India – collectively face an eye-watering $428 trillion savings hole by 2050.

Meanwhile, the global population is older than ever before. As of 2015 there were are around 451,000 living centenarians , and this number is set to increase eightfold over the next three decades. In the US, they’re the fastest growing age group. In the UK, there are now so many that the Queen has hired extra staff to send them cards. In fact, the majority of children born into wealthy countries today can expect to celebrate their 100th birthdays.

This is part of the problem. Even in 1960s America, more than two decades after state pensions were first introduced, people were typically only able to enjoy them for around five years – since the retirement age was 65 and the average life expectancy was barely 70 .

But for centenarians, retirement could be up to seven times longer. And with companies moving away from expensive final-salary pensions, those hoping to maintain an annual salary of $44,564 – the US national average – will have to save around a million dollars .

Instead, a substantial number of these natural marvels may have to work. What kinds of job will they do? Will they be well enough? And will anyone want to employ them?

Those hoping to maintain an annual salary of $44,564 – the US national average – will have to save around a million dollars

The answer to the first question may surprise you. Across the globe, from California to Poland, to India, centenarians are already hard at work. And it seems no profession is off the table. There are far too many to list, but they include barbers, such as Anthony Mancinelli, who has been cutting people’s hair for 95 years (he started in 1923, when he was 12); athletes, like Stanislaw Kowalski, who broke a World Record for a 100-metre run at 104; and YouTube stars, namely Mastanamma, a great-grandmother aged 107, who teaches her million followers how to cook dishes such as fried emu egg .

View image of (Credit: Getty Images)

In fact, older people often want to work. This is something Peter Knight, an entrepreneur based in the UK, can relate to. He set up the recruitment company Forties People about four years ago. They specialise in hiring mature candidates. “There’s no upper limit. We have in the past had a client who is 82 and their employee, the oldest is 94,” he says.

The 94-year-old had retired three times from the same company, which looks after the records of Royal Marines – and each time he kept going back into the office to see his colleagues. He started helping out and one thing led to another, until they decided they would pay him a token amount so that he could come and go as he pleased. “He was part of the furniture then.”

Of course, some jobs are just too good to give up. The 92-year-old British television presenter and national treasure Sir David Attenborough, who makes TV programmes about wildlife for the BBC, is reassuringly confident that he’ll make it to 100 – and he’s said several times that he has no plans to retire. Who would, when the job involves sneaking up on sloths , honing your wolf call and playing with baby gorillas?

View image of (Credit: Getty Images)

“We don’t have a compulsory retirement age anymore in the UK, but if you take the higher education sector you have people continuing to lecture well into their 70s,” says Jane Falkingham, a gerontologist and director of the  Centre of Population Change  at the  University of Southampton . “I think the oldest professor we have in my faculty is in their mid-70s. But of course academia is quite a nice life.”

For Frankland, continuing to work was a practical decision – though he is clearly passionate about his subject. “I used to be a manic gardener, but now I can’t do that,” says Frankland. “All the things that I used to do, at the age of 106, I cannot do. So what is left? I do quite a lot of reading, mostly scientific stuff rather than novels or anything like that.”

At Forties People, there’s no real pattern to the roles that they recruit for, though most are office-based. “We’ve had three press companies phone us in the last few weeks,” he says. After trying to recruit younger receptionists and HR staff and finding them to be unreliable, they had decided to try older workers who can prioritise their jobs.

For people with more physically demanding jobs, continuing work is more of a challenge. But this might not always be the case. “Technology is changing the work that we do,” says Falkingham. “So actually some of the more manual jobs in terms of hard labour are being done by machines. It’s changing the nature of work, which will facilitate people working longer as well.”

So will most people be well enough?

In fact, most centenarians are surprisingly healthy. They might have more wrinkles than a naked mole rat, but on the inside, they’re often in better shape than much younger pensioners. One recent study found that they tend to suffer from fewer diseases than those who are up to two decades younger.

They’re not doing badly mentally either. While it’s true that some abilities decline as we age, so-called “crystallised intelligence” – the skills and knowledge we’ve built up over the years – continues maturing well into later life. Back in 2016, scientists examined the health and abilities of centenarians who had registered to vote in New York and found that they showed very few signs of senility and were, overall, functioning at a remarkably high level.

And while retiring early is generally thought to be better for your health , in some circumstances giving up work might achieve the opposite. One study of blue collar workers in Austria found that men who retired three and a half years early were 13% more likely to die by the age of 67 – particularly if they were single, lonely and used it as an opportunity to reduce their physical activity.

South-west of Japan’s main islands, in the East China Sea, is a tropical outpost that seems to back this up. Okinawa is famed for its high proportion of centenarians; it’s been estimated that roughly one in every 2,000 people there are over the age of 100.

Over the years, researchers studying this remarkable place have noticed several aspects of the Okinawan lifestyle that might explain their longevity. These include eating lots of vegetables and fewer calories overall than the average American – but also their attitude to work.

There is no word for “retirement” in the Okinawan language ; the locals, many of whom grew up as farmers and fisherpeople , may carry on working until they die. Elderly residents live by the principle of “ikigai”, which is loosely translated as “having a reason to get up in the morning”. Predictably, the island boasts the world’s only “centenarian” pop band . KBG48 has played a sell-out Japanese tour and only accepts members over the age of 80.

View image of (Credit: Getty Images)

So centenarians aren’t as decrepit as you’d think, and there are plenty of jobs that they can choose from. But will anyone want to employ them?

Well, yes. “The future has got to be older, I think,” says Knight. In his view, older workers have several advantages over their more fresh-faced colleagues, including the ability to work with people and superior communication skills.

Besides, elderly workers are likely to be experts in their field. Frankland was invited to give evidence in court at the age of 99. The case involved a driver who claimed an accident wasn’t their fault, but the consequence of an allergic reaction following a wasp sting. He persuaded the court that this was unlikely and the accused was eventually convicted.

There are challenges, however. Knight says several clients have rejected older candidates because they were too good – they were seen as a threat to the person employing them. For example, one worker successfully managed several crises while a senior colleague was on holiday. But instead of being pleased, “they got rid of her because she became more popular in the office. They asked for someone else without her skills or experience.”

Another problem centenarians may face is slightly more obvious – they’re old. “If you look on a company website and they say ‘this is a young, dynamic, vibrant team’, the last thing they want is a mature worker there,” says Knight. There’s a cultural gap. Imagine telling a colleague with grandchildren about that rave you went to at the weekend. “It’s like working with your parent or your grandparent.”

Nevertheless, one place that’s leading the way is Japan. With the longest life expectancy on the planet and birth rates plunging to a record low, nearly a third of the nation’s population is over the age of 65. This demographic reality has led to new government-backed rewards for companies that hang on to older workers. They’re also considering raising the age from which people can choose to claim a state pension to 70 .

View image of (Credit: Getty Images)

The cosmetics company Pola, which sells skincare products, health foods and underwear at department stores across the country, now employs around 1,500 people – mostly women – in their 70s, 80s and 90s. They’ve often built up strong customer bases over the years, and older teams can outperform those that are more youthful.

So how does Frankland find working at 106? “I have all sorts of physical barriers now, deafness is one of them. Just handling things is difficult,” he says. “Looking for journals and things is an awful bore. I’m very limited, physically. I always used to say yes to everything and now I am beginning to say no.”

Frankland’s mental abilities are a different story. It would be hard to find a more engaging interviewee – at this point I have been regaled with stories about everything from his time as a Japanese prisoner of war to the book that inspired him to become a doctor. (If you’re interested, it’s The Story of San Michele by Axel Munthe.)

It may not be everyone’s idea of an idyllic later life; for many, ill health will mean that working past the age of 65 is impossible. But evidently it can be done. And if this is the future of work, offices are about to get a lot more interesting.

To comment on this story or anything else you have seen on BBC Capital, please head over to our   Facebook    page or message us on  Twitter .

If you liked this story, sign up for the weekly bbc.com features  newsletter  called “If You Only Read 6 Things This Week”. A handpicked selection of stories from BBC Future, Culture, Capital and Travel, delivered to your inbox every Friday.

mundinewsadmin

View all posts