Our ability to extend human lifespans is improving dramatically, but whether there is any natural limit to how far we can push is an outstanding question. New research contradicts claims that we’re approaching a maximum human lifespan.
The question of whether or not there is a limit to how long humans can live has fascinated scientists for decades. While answering this question is likely to require a better understanding of the physiological process of aging, researchers have long tried to divine trends in demographic data that could give clues as to what the upper limit might be.
One study predicted that the human lifespan is unlikely to go past around 150 years no matter what medical innovations we come up with. Another came to the even more conservative conclusion of 115 years. But a new study that uses novel statistical techniques appears to show that people born between 1900 and 1950 could live much longer than previous analyses suggest, opening up the prospect that no natural limit is currently on the horizon.
“In most of the countries we examined, we project that the maximum age will rise dramatically in the future,” David McCarthy from the University of Georgia told LiveScience. “This will lead to longevity records being broken in the next 40 years or so.”
While previous studies of this kind have often grouped people based on their year of death, the researchers instead lumped together people born in the same year. They used this approach to analyze data from the Human Mortality Database, which contains records of hundreds of millions of people from 19 countries as far back as 1700.
What they found was that those born between 1910 and 1950 saw their risk of dying increase more slowly with each extra year compared to older generations. Because people in these groups have yet to reach extreme old age, it’s impossible to tell how long the oldest will live, but the trend suggests it could be considerably longer than previous generations.
In their paper in PLOS One, the researchers explained that if an upper limit on lifespan did exist, you would expect to see a compression in the distribution of age at death. If fewer people are dying at younger ages, the rate of mortality at older ages would have to increase to compensate.
But that was not what the team found in the data they analyzed, suggesting that mortality was instead being postponed. The authors suggest this sudden step change in lifespans could be due to the rapid improvements made in medicine and public health at the start of the 20th century.
Not everyone is convinced, though. Jan Vijg from the Albert Einstein College of Medicine in New York, who was behind the prediction of a 115-year lifespan, told New Scientist that the researchers’ analysis relies on an assumption that mortality risk increases exponentially up until around 105, after which it plateaus. They aren’t the first to rely on this assumption, but not everyone agrees with it, he says.
It’s also important to remember that no matter what the demographic data shows, human lifespans will ultimately be governed by both their physiology and medical innovation. “The duration of life is at its heart a biological phenomenon, not a mathematical one,” Stuart Jay Olshanky from the University of Illinois Chicago told LiveScience.
However, that’s likely to lead to an upward revision on these predictions, if anything. There’s a growing revolution in the science of aging underway, and research is starting to show that there are a host of medical interventions that could slow or even reverse aging. If the field lives up to its promises, we could be on the cusp of another step change in lifespans similar to the one the researchers predict for those born in the early 20th century.
Image Credit: Matt Bennett / Unsplash
