For as long as human beings have existed, we’ve pondered whether we can make our existence last longer. With rumours swirling around that today’s 30-year-olds will be tomorrow’s centenarians, I did the research to see how much is fact and how much is fiction.

I was born in 1993, which means that I exist at the younger end of the Millennial spectrum (those born between 1981 and 1996, now aged between 28 and 43). If you believe what the life insurance salesmen have to say, then members of my generation are more likely than any generation before to reach 100 years of age.

Over the past few decades, life expectancy has seen a remarkable leap across the globe. Back in 1960 (which is the earliest year that the UN started collecting global data) the average person could expect to live to a modest 52.5 years. Fast-forward to today, and that average has jumped to 72. In the UK, where they’ve been keeping records for much longer, the shift is even starker. In 1841, a British baby girl was expected to make it to just 42 years old, while a boy could hope for around 40. But by 2016, those numbers soared, with girls reaching an average of 83 and boys 79.

So, what’s the takeaway here? Thanks to the marvels of modern medicine and the power of public health, it looks as though we’re sticking around a lot longer than we once thought possible. But is it really the upward curve we think it is – and will it continue on that trajectory indefinitely?

Argument 1: Life expectancy is up

This rise in life expectancy stems from a mix of factors that came into play in the last century, like advances in public health, better nutrition, and modern medicine. Vaccinations and antibiotics slashed childhood mortality and prevented outbreaks of disease from turning into epidemics. Workplace safety standards improved, seatbelts became a thing and fewer people smoked. Heck, we even got rid of the asbestos in our ceilings and the lead plumbing in our kitchens. All of these changes addressed what we might call “preventable deaths”, i.e. deaths caused by external factors, paving the way for more people to age as nature intended.

By 2030, one in every six people worldwide will be aged 60 or over. That means the population of those 60 and older will grow from 1 billion in 2020 to a hefty 1.4 billion in the span of a decade. Fast forward to 2050, and this group will double, hitting 2.1 billion globally, with those aged 80 and above expected to triple to 426 million.

This shift towards an older population — known as population ageing — began in wealthier countries (like Japan, where 30% of the population is already over 60). But now it’s low- and middle-income countries seeing the biggest change. By 2050, nearly two-thirds of the world’s over-60 population will be living in these regions.

Argument 2: Life expectancy is the same

It might be time to acknowledge that the idea of our current super longevity is at least a little bit fueled by myths about our ancestors. Many of us believe that the ancient Greeks or Romans would have been astonished to see anyone living past middle age. But while medical advancements have indeed transformed healthcare, the assumption that our life span has skyrocketed is somewhat misleading.

What’s actually increased isn’t how long we can live but rather how many of us do live that long. Consider that life expectancy statistics usually reflect an average, which is heavily influenced by survival rates during infancy and childhood. Much of human history has seen high child mortality rates, and this reality skews average life expectancy strongly downward.

That’s why it’s commonly believed that people in ancient Greece or Rome lived to just 30 or 35. However, this doesn’t mean that adults simply dropped dead at 36; rather, high infant mortality brought down the average. In many ancient societies, a third of infants didn’t survive to their first birthday, and half of children didn’t reach age 10. For those who survived childhood, the odds improved sharply, with some living well into their 70s or beyond.

In truth, the maximum life span in ancient societies likely wasn’t drastically different from today. Age limits in Roman politics illustrate this beautifully: the cursus honorum – the structured path of political offices for ambitious young men – required a minimum age of 30 to stand for quaestor, the first official position. For the esteemed role of consul, however, the minimum age was set at 43.

So life may have been slightly shorter on average, lacking today’s medical interventions, but it was not dramatically so. A society can have a low average life expectancy due to infant mortality and maternal risks, yet still include individuals who live into their 80s or 90s.

This is why using averages (rather than other statistical measures like the median) is dangerous.

Argument 3: Life expectancy is capped

Using demographic survivorship metrics from national vital statistics in the eight countries with the longest-lived populations – Australia, France, Italy, Japan, South Korea, Spain, Sweden, and Switzerland – as well as Hong Kong and the United States, a recent study examined trends in death rates and life expectancy from 1990 to 2019. Their findings suggest that since 1990, gains in life expectancy have slowed across all of these regions.

It makes sense if you consider that we’re comparing this period to what came before. In the early twentieth century, advances in public health and medicine sparked a longevity revolution, marked by significant leaps in life expectancy at birth. While it previously took centuries to see just a one year increase in average life expectancy, the twentieth century saw a dramatic shift, with life expectancy rising by about three years per decade.

So, does that mean that life expectancy will just keep rising, as predicted? Not exactly. While we’ve done a great job of addressing the mortality risks that we can prevent, we neither fully understand nor know how to stop ageing from happening. Until we can do that, it seems very likely that our life expectancy will remain capped under 100 years of age.

The stats are fascinating: for female life expectancy to go up from 88 to 89 years in countries with long-lived populations, there would need to be a 20.3% drop in mortality across all ages and causes. For men, raising life expectancy from 82 to 83 years would require a 9.5% reduction in mortality at every age.

Between 1950 and 2019, the age at which people die has become more predictable in long-lived populations, with fewer people dying very young or very old. This trend has occurred even as life expectancy has gradually increased. Although it’s theoretically possible that more people could start living to even older ages, there’s no strong evidence for this yet. Radical increases in lifespan seem unlikely unless major progress is made in slowing the ageing process itself.

What does it all mean?

Well… I’m still not sure, actually. I guess it’s true that life expectancy is up across the twentieth century as a whole, but not really because we’re getting older; rather, because we’re not dying younger. More of us will get older, but older means 80s, not 100s. At the end of the day, only a few of us will live to be 100 or more. That’s not very different from what happened in ancient Rome, where Cicero’s wife Terentia lived to 103 and actress Lucceia performed on stage at 100.

At the heart of all this lies our fragile understanding of ageing, this curious side-effect of mortality that we hate and crave in equal measure. Until we figure out how to stall it – or even reverse it – we really have to question our desire to live longer. After all, where’s the fun in spending the final two decades of your life as an old person?

Unless, of course, you sell retirement products. Then life expectancy is a wonderful marketing tool.

About the author: Dominique Olivier

Dominique Olivier is the founder of human.writer, where she uses her love of storytelling and ideation to help brands solve problems.

She is a weekly columnist in Ghost Mail and collaborates with The Finance Ghost on Ghost Mail Weekender, a Sunday publication designed to help you be more interesting.

Dominique can be reached on LinkedIn here.