Human lifespan has a limit and we might have reached it.
S. Jay Olshansky, who studies the upper bounds of human longevity at the University of Illinois Chicago, believes people shouldn’t expect to live to 100. Most, he contends, will reach between 65-90.
Biology is holding us back, Olshansky said. Human evolution favors growth and reproduction, not living to excessive ages. As people grow older, their cells and tissues accumulate damage . Breakdowns of one kind or another happen more frequently and get increasingly difficult to repair. Scientists believe there are likely many genes that affect lifespan. Aging is a complex process that isn’t well-understood .
Olshansky knows his viewpoint isn’t popular.
The longevity business is booming . People are flocking to longevity meetings and taking compounds they hope will extend their lives. Investors are backing scientists researching techniques to reprogram cells to a younger state with the goal of restoring functions that diminish with age. Longevity influencers argue that if they can live long enough, scientific breakthroughs will keep them going indefinitely.
“We are going to start to understand how to rejuvenate and revitalize ourselves. This is what science does,” said Dr. Peter H. Diamandis, a 63-year-old entrepreneur who runs longevity trips for investors to meet scientists in the field.
And yet, at 70, Olshansky is more confident than ever in his prediction. He and his colleagues have been studying demographic and mortality data from 1990-2019 in the U.S. and developed countries with the longest-living populations. Over those 30 years, they found that life expectancy slowed. Progress stopped even before the Covid-19 pandemic drove life expectancy rates down .
“We waited three decades to see what would happen,” he said. “I had a lot more hair back then.”
Generational change
Certainly, the number of people 100 or older has grown. Olshansky said their ranks will increase most dramatically beginning in 2046, the 100th anniversary of the baby boom that followed World War II. But that demographic bump won’t change average life expectancy. Olshansky predicted that under the best of circumstances, less than 10% of newborns will make it to their 100th birthday.
Jan Vijg , chair of genetics at Albert Einstein College of Medicine in the Bronx, reached a similar conclusion from a different angle. He has studied the maximum verified age the oldest people died at in different countries. The maximum age at death increased gradually at least from the 1950s until the 1990s, when it appeared to plateau.
He isn’t surprised that Jeanne Calment, a French woman who died in 1997 at 122, still holds the world record of the oldest verified age at death. There are now hundreds of millions more people who have reached old age under optimal conditions—benefiting from clean water, antibiotics, improved treatments for top killers such as heart disease and cancer, and healthier lifestyles .
If lifespan had no limit, some of those centenarians would have broken Calment’s record by now, he argued.
“It seems this is the end,” Vijg said.
Nobel laureate Venki Ramakrishnan explained in May to a packed audience at Harvard University the many reasons, “Why We Die,” the name of his new book. Ramakrishnan doesn’t believe current interventions will dramatically extend lifespan. Techniques to reverse aging would have to help every system in the body, including the brain, over a long period.
“It is more complicated than people think to engineer away the causes of aging,” he said.
Kaare Christensen , co-author of a paper predicting most newborns born in the 2000s would live to 100 if medical progress continued, said it is too soon to know who is right. Future advances could make up for stalled life expectancy gains.
“The setback could be temporary,” he said.
Christensen, who runs studies on very old people at the Danish Aging Research Center in Denmark, said people in their 90s have better cognitive function and healthier teeth over their lifetimes than counterparts of the same age born just 10 years earlier.
“I would say prepare for your 90s instead,” Christensen said.
Old-age debate
Olshansky’s foray into the limits of lifespan began in 1990 when he published a paper in Science stating that life expectancy wouldn’t rise dramatically even if diseases including cancer and heart disease are eliminated. He has been fighting about it ever since.
James Vaupel, a demographer, pushed back. In a 2021 paper , Vaupel pointed to statistics showing that since around 1840 life expectancy at birth has increased almost 2.5 years per decade in some countries.
Vaupel and Olshansky published dueling papers over the decades until Vaupel’s death at age 76 in 2022.
Steven Austad, a professor of biology at the University of Alabama at Birmingham, was asked at a 2001 scientific meeting when he thought the first person to live to 150 would be born. “I think that person is already alive,” Austad replied. Austad said he based his answer on optimism that scientists will figure out how to change the biology of aging.
When Olshansky heard about the exchange, he bet Austad that wasn’t true . In 150 years, he argued, there still wouldn’t be a person alive at 150 . The men wagered $150 each, which they put in a fund to pay out in 150 years, with the winner’s heirs to reap the profit. A decade ago, they each added another $150 to the account.
Austad said he agreed with Olshansky that most newborns born now won’t live to 100. But he thinks his optimism that someone will live to 150 is justified. He pointed to a study showing the compound rapamycin extended the lifespan of mice, even if they start getting it later in life. Some longevity enthusiasts are taking rapamycin themselves . Studies on other potentially antiaging compounds are under way.
“If any turn out to work,” Austad said, “they will win my bet for me.”
Olshansky thinks any intervention won’t extend life that far. “Not in these bodies,” he said.
The wealthy and well-educated already tend to live longer, a group that includes many of Olshansky’s critics. “Your chances of making it to 100 are better than anyone else,” Olshansky said of his naysayers. “But overall, your odds are still slim.”
Write to Amy Dockser Marcus at Amy.Marcus@wsj.com
