Can Humans Live Forever? What Longevity Science Says About the Limits of Life

People have dreamed of living forever for as long as there have been stories. Today, some scientists say we may be approaching a natural limit, while others think the limit can be pushed. This article explains the debate and what the evidence shows so far.

What is the oldest age anyone has reached?

122. Jeanne Calment of France died in 1997 at age 122, which most experts agree makes her the longest-lived human ever, according to the Oklahoma Medical Research Foundation (OMRF). In the decades since, no one has come close to her record. See also How the Life Expectancy of Americans Changed Over the Last Century.

Is there a limit to human life?

One famous study says yes. Researchers at the Albert Einstein College of Medicine published a paper in Nature in 2016 called “Evidence for a Limit to Human Lifespan.” They found that the age at death of the oldest people rose quickly between the 1970s and early 1990s, then leveled off around 1995. They put the average maximum human lifespan at 115 years and calculated 125 as the absolute limit. They described Calment as a statistical outlier. The lead researcher said that further progress against infectious and chronic disease may keep raising average life expectancy, but not the maximum lifespan.

Do other scientists agree?

Many do not. Scientific American reported that some scientists questioned the interpretation, and that one researcher noted that a fixed human limit would make people different from every other experimental species tried. A peer-reviewed commentary titled “No limit to maximal lifespan in humans” notes that average life expectancy keeps rising while the maximum does not, and that estimates of a natural limit based on demographic data range from 115 to 126 years. It argues that in animals, anti-aging interventions postpone age-related disease and extend maximum lifespan, and that in humans such interventions have not yet been tried. Reasonable scientists disagree.

What do animal studies show?

That aging can be slowed in the lab. The same commentary lists dietary restriction, the drug rapamycin, and genetic changes as interventions that extend lifespan in animals. The OMRF article describes researchers studying drugs called “mimetics,” which imitate some effects of caloric restriction, including the diabetes drug metformin and the immunosuppressant rapamycin. Some of this work is funded by the National Institute on Aging. But results in animals do not always carry over to people. Scientific American notes that at least one strategy, caloric restriction, is much less effective in wild mice or monkeys. And the commentary is clear that anti-aging interventions in humans have not yet been implemented, so there is no proof that they extend human life.

Is the goal a longer life or a healthier one?

Many researchers say the second. An OMRF scientist told the foundation that pushing the maximum lifespan further is not very interesting if it does not come with quality years. That focus on years of good health, sometimes called healthspan, is where much of today’s research is aimed.

Would living forever even be good?

Philosophers disagree. Some argue that endless life would become tedious, and others dispute that. See What Do Philosophers Say About Death? for the debate. For a very different bet on the future, see Cryonics: What It Is and What Science Says. And for what people die of today, see What Are the Leading Causes of Death in the United States?.