Humans may not have reached a maximum lifespan yet — people could soon live to 120 and beyond

• A new mathematical model suggests human beings might not have reached our 'maximum age' yet.
• But scientists still think it's going to be hard for most superagers to live past 115.

When New Yorker Helen Reichert died at 109 years old, she loved Budweiser and was considering taking up smoking again, a habit she'd enjoyed for more than 80 years.

Her little brother, Irving Khan, followed in her footsteps four years later, taking his last breath at the same age — 109 — making him the oldest active Wall Street investor who ever lived.

For a while now, superagers like Reichert and Khan have died around this same age, with most living to around 110 or 115, tops.

There's seemingly only one woman who's cracked age 120 – Jeanne Calment – the French woman who was reportedly 122 years old when she died in 1997.

Now, a team of math whizzes suspect it's possible that all these so-called superagers may soon be outlived.

In a paper published Wednesday in the journal PLOS One, David McCarthy, a risk management professor at The University of Georgia, calculated that over the course of the next few decades, we may see people — particularly, women — surpassing age 122.

In Japan, for example, McCarthy's models suggest women born in 1940 may achieve a maximum age somewhere around 125 or 130 years old. In the US, age 120 to 125 is where women born in 1940 may cap out.

McCarthy says that taken together, all these mathematical models suggest that our maximum age isn't biologically constant, it's increasing, at least for now.

"If you believe our analysis and our projections turn out okay, and, you know, the world doesn't collapse, there will likely be some individuals who will break the current longevity record," he told Insider. "The finishing line is moving forward."

Life after 115 is still rare, experts say

Life expectancy in the US is going down, but that's not because more old people are dying. Average life expectancy is hovering around 76 years old because many younger Americans are dying before they even have the chance to get old due to a complex web of factors including social isolation, racism, easy access to guns, COVID-19, and drug overdoses.

If Americans can manage to make it past 75 however, it turns out they do pretty well soldiering on for a while. Trends suggest that more people are making it to their 70s, 80s, and 90s now than in generations prior.

Brandon Milholland, a former post doc at the Albert Einstein College of Medicine, co-authored a 2016 Nature paper that suggested the limits of human lifespan haven't really moved since the 1990s. The maximum age of a person still hovers, on average, around 115, he said.

"It's not an unbreakable limit, it's an unbroken one," Milholland told Insider. He suspects there may be ways people will eventually figure out how to reduce their biological age as they get older. If we unlock some of those, people might start living even longer.

"The thing that's holding us back right now is we're doing a lot of treating of the symptoms of aging, but not aging itself," Milholland said.

For now, Milholland and McCarthy both agree on some rough version of Gompertz's law: that a person's risk of death doubles roughly every eight years through adulthood. But McCarthy's new model seems to suggest that risk then plateaus at some point once people pass their 100th birthday.

Milholland disagrees with the idea that a person's risk of death levels off in very old age. It doesn't make sense biologically, he says, and it isn't supported by recent data on very old people in Italy and France either.

"The data is so sparse" on people who get that old, Milholland said, a truth which McCarthy acknowledges.

"Like all projections, these are obviously uncertain," McCarthy said.

It's also possible that even if there are not real improvements in humans' maximum age on the horizon, we may still see a few more people hit age 120 or older in future decades, simply because there were more people being born during the postwar baby boom of the 1940s, 50s, and 60s. More babies born means more of a chance for extremely old outliers in the data.

Aging experts are working on drugs to extend human lifespan

Experts are working on figuring out whether cheap drugs like rapamycin or metformin could extend the healthy lifespans of people, like they do other animals including mice and flies. Advances in understanding degenerative diseases like Alzheimer's could also help scientists untangle which genetic risk factors, and which protective factors, help decide who lives and who dies.

But there's probably no precise superaging recipe for all of us. Rather, a person's lifespan is likely determined by a mix of many complex and elusive factors, including genetics, lifestyle, environment, and other variables.

"To think that that recipe would be the same for each and every person, I think we know better than that now," Northwestern professor Emily Rogalski, a cognitive neuroscientist who studies the brains of superagers, told Insider.