Humans shouldn’t expect to live past 115 years of age.

That’s according to a study published earlier this month in the journal Nature.

The authors analyzed the death rates of humans from 40 different countries. The data showed that by the mid-1990s, “improvements in survival with age tend to decline after age 100, and that the age at death of the world’s oldest person has not increased since the 1990s,” according to the study.

The results suggested that maximum life span for humans has peaked at 115 years.

Aging 15 years past the century mark doesn’t sound too bad. But even with advances in modern medicine, have we yet discovered our proverbial fountain of youth?

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A complex topic

Healthline turned to two prominent experts in the field of aging to get some perspective.

Can humans live past 115 years of age, and if so, what will it take for us to achieve that?

Not surprisingly the answer is as complex as the aging process itself.

“The average life span will likely extend out, maybe to 122,” said Kim D. Finley, Ph.D., associate professor of molecular biology at San Diego State University. “I don’t know if we could get to 150. It’s hard to predict because no one has.”

Dr. Leonard Guarente, director of the Paul F. Glenn Center for Science of Aging Research at the Massachusetts Institute of Technology (MIT), told Healthline he thought the report’s methodology was solid.

“[But] it’s not prospective,” he said. “If there are one or two technical breakthroughs it could change the calculus on how long people live in the future.”

Both experts agree that scientists are just beginning to truly understand what happens at a molecular level in our bodies when we age.

Promising research and treatments do exist, they added. But science alone won’t provide a magic pill to expand the human life span.

That’s because the genes we inherit and the environment we live in hold an enormous influence on our life span outcomes.

What’s more, they argued, all this talk about maximum life span is a disservice to people. Instead, our priorities should be about extending our health span. How long we can sustain an active and healthy lifestyle?

That’s where scientific breakthroughs will produce the most significant advancements when it comes to aging.

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It’s all relative

Ironically, growing old is a relatively new experience for humans.

Life expectancy hovered around 40 years of age for thousands of years. Only in the last century did humans start to increase how long they lived.

Today the average man living in the United States is expected to live to about age 76. For women that number hovers around age 81.

“If you inherit perfect genes, you’re one of these individuals who can live to 115,” Guarente said. “But almost nobody’s genes are perfect.”

For most of us with imperfect genes, outside forces play a major role in determining how long we live.

These factors can include things such as whether we smoke, our access to clean water, antibiotics, and nutrition.

“It depends on the population,” Finley said. “In India men outlive women, but if you have advanced medicine and hygiene, women tend to live longer than men.”

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Cell decline

But even if you optimize all the factors such as sanitation and vaccines, Guarente noted, your cells will eventually endure damage and lose their integrity.

“The aim is to try and slow that down,” he said.

Helping that “slowdown” is the philosophy behind Elysium Health. The company released its first product earlier this year, a supplement called Basis. It’s designed to help keep cells healthy during the aging process.

Guarente is one of three founders of the company and serves as its chief scientist.

The supplement contains two key components that target metabolic repair. The first is called nicotinamide riboside. This is a precursor of the coenzyme NAD+, which helps cells produce energy. It can also promote DNA repair and detoxification, among other things.

The second component is called pterostilbene. Similar to the NAD+ precursor, it also encourages metabolic health.

Much of the development of Basis is rooted in Guarente’s 25-year career at MIT. He is known for his research on isolating the protein sirtuin.

“When sirtuin proteins are active the aging process slows down,” he said.

Finley’s research also focuses on proteins but from a different perspective. Her most recent study looked at the efficacy of specific cells and the development of neurologic disease in fruit flies.

These “self-eating” cells, also called autophagy, have the ability to keep proteins from developing in the brain.

“But if you don’t have this autophagy working well,” proteins can build up and diseases such as Alzheimer’s can develop, she said.

Finley also noted that these autophagy pathways are regulated by nutrition.

“When insulin is high, they shut off,” she said.

This circles directly back to the notion that lifestyle — making informed choices — is just as important as science in the quest to extend life.

“None of us can change our genes, but if you can take care of lifestyle choices,” Finley said, that’s where health span and life span will benefit.

Guarente said the idea of humans living well past 100 years of age is not what inspires him. His motivation is fueled by the idea of providing a quality health span for people.

“That you can stay healthy, live, work, play tennis,” he said. “That’s the most important thing.”