What if we could live to 120 years old?

While humans have long sought the secret to eternity, some argue that the ability to do everything we want millions of times over would make living forever a dull, meaningless nightmare. Living to 120 is far from eternity. Nevertheless, the prospect of those extra decades raises questions about the way we might structure our social lives and careers, plan our families and manage our health.

When Pew Research Center polled Americans, it found that only a minority (38%) said they personally would want to live to 120. “We were a little surprised by the amount of ambivalence,” says Cary Funk, associate director of research at Pew Research Center.

Ambivalence aside, this kind of longevity is becoming more common. In the UK, one-third of babies born in 2013 are expected to live to 100, according to the Office of National Statistics. In the US, the Census Bureau projects that those 85 and older will more than triple between 2012 and 2060 to reach 18.2m.

One of the questions this raises is whether or not good health will accompany that longevity. Certainly, advances in medical science and technology are pointing to a world in which people could be kept healthier for longer.

Sensor-based wearable or implantable technology will make it possible to generate and transmit health data for real-time analysis, helping keep track of medical conditions and paving the way for a world in which individuals could be alerted about signs of illness or disease before symptoms have even appeared.

This could reverse the traditional pattern of healthcare, says Laura Carstensen, director of the Stanford Center on Longevity. “The real focus of healthcare will become health as opposed to disease,” she says.

And if this were to result in a greater number of healthy years for those living to 120, it would have significant implications for other aspects of life, reshaping the traditional life stages of education followed by work, parenting and retirement.

Among other things, Professor Carstensen sees the proportion of people’s lives spent on child-rearing shrinking if lifespans last 120 years. “Parenting becomes something one does for a small period in life,” she says.

She adds that when people live longer, more family members could participate in raising children. “Not only will there be parenting roles but grandparenting, great-grandparenting and even great-great-grandparenting,” she says. “So we need new norms for families and for what constitutes a family.” Those new norms may also apply to marriage and partnership. “It certainly gives you the opportunity to have multiple long-term relationships, whatever form they take,” says Professor Carstensen.

Of course, with longer lives come greater financial burdens; with 120 as the norm, careful planning will be required by both individuals and policymakers.

For governments, the challenge will be how to adapt state pension schemes. “It’s not sustainable to keep adding years to this kind of pension support,” says Ann MacDougall, president of Encore.org, a US nonprofit that helps people who have completed or are nearing the end of their primary careers to enter public service.

She argues that, with longer lifespans, people will also need to think about having several careers—with some moving into the nonprofit sector to bring experience and knowledge acquired in the corporate world to bear on solving social problems.

This means that education, the bulk of which now takes place in the early part of a person’s life, will become a continuous process. “If done right, we can reskill and redirect this population for an additional chapter of work,” says Ms MacDougall.

As many experts point out, however, a longer life is only desirable if it comes with greater well-being, including happiness, health and prosperity. “That’s where the big challenge comes now: Can we develop a therapeutic that can improve the quality of old age? Not to make us immortal, but to give us a nice long lifespan that is very healthy,” asks Dr Cynthia Kenyon, professor at UCSF School of Medicine in a recent interview done for National Geographic’s Breakthrough series.

Drug development is only one part of the solution, of course. At the Stanford Center on Longevity, research is organised around three areas: mind, mobility and financial security. “We think of them as three legs of a stool,” says Professor Carstensen. “And if any one of those three legs is missing, the stool falls over.”