Slowing growth in life expectancy means few people will live to 100

Will you live to 100? For the average person, the answer is probably no, as growth in life expectancy is slowing across wealthier countries, despite advances in healthcare and living conditions. This suggests there may be a biological limit to how old we can get, although some researchers believe further advances are possible.

The current slowdown is a marked contrast to the 20^th century, during which average life expectancy at birth grew in wealthier regions by three years per decade in a period of what researchers call radical life extension. While people born in the mid-1800s could expect to live 20 to 50 years, by the 1990s, it had reached the 50s to 70s.

Extrapolating the trend, some people at the time began to predict that newborns in the 21st century would regularly live beyond 100, but now that we have reached that point, it seems this was too optimistic.

S. Jay Olshansky at the University of Illinois in Chicago and his colleagues analysed mortality data from the 1990s to 2019 across nine wealthy countries, including the US, Australia, and South Korea, and also Hong Kong. The 2019 cutoff was intended to avoid any effects of the covid-19 pandemic. The team found that average life expectancy at birth rose by 6.5 years across the study period, on average. In the US, it reached 78.8 in 2019, while in Hong Kong it was 85.

But the rate of increase slowed in most countries in the period of 2010 to 2019, compared with the previous two decades. The US fared the worst, perhaps because of the ongoing opioid crisis, says Olshansky. In contrast, Hong Kong was the only place to see a rise in the rate of life expectancy gains since 2010, but what is driving this is unclear, he says. It could be because people are gaining better access to healthcare compared with elsewhere, he says.

Based on past trends, the researchers predict that average life expectancy at birth may never exceed 84 for men and 90 for women. They also calculate that just a minority of newborns today will live to 100.

The recent slowdown could be because the biggest advances in improving our environment and healthcare were already achieved in the 1900s and humans are reaching a biological limit to ageing, says Olshansky. Jan Vijg at the Albert Einstein College of Medicine, New York, thinks similarly. “There’s some sort of biological limit that keeps us from getting any older,” he says.

But Gerry McCartney at the University of Glasgow, UK, says the slowing growth over the past decade may largely be down to policies in many of the countries analysed, which have led to cuts in social benefits and healthcare services, and driven up poverty. Without these, life expectancy increases may not have slowed, so with the right policies, life expectancy could keep rising, he says.

In fact, Michael Rose at the University of California, Irvine, thinks there is no limit to how long humans can live. With the right investment in anti-ageing research, we could see radical life extension again this century, at least in wealthier countries, he says.

Even with the recent slowdown, Olshansky says it is positive that life expectancy is still increasing. “We should, of course, celebrate the fact that we can live this long,” he says.