How do you live longer? Your genes may help

Scientists have long believed that longevity is determined by lifestyle choices; However, a new study reveals that genes may play a larger role in determining how long people live.

Genetics accounts for more than half of the differences in lifespan, twice as many as previous estimates. Yet this discovery may echo what people see on their family trees or what they hear during their annual physical.

“It’s not surprising at all,” said Dr. Deborah Kado, co-director of the Stanford Longevity Center, who was not involved in the study. Although scientists agree that most traits have a natural and cultural component, lifespan was thought to depend largely on environment.

The finding, published Thursday in the journal Science, suggests that longevity is similar to other complex traits – such as cholesterol levels and osteoporosis risk – that are shaped by many genes, but also strongly influenced by how and where people live.

Previous studies have underestimated the influence of genetics because they relied on data from people born before the 19th century. These people typically died from infectious diseases and accidents before vaccines, medications, modern hygiene practices, and safety regulations were widely available.

When these factors were included in older studies, they overshadowed the genetic factors influencing age. Uri Alon, the study’s lead author, explains that by cleaning the data to exclude these factors, “the genes shine fully.”

“People thought, ‘Oh, genes are probably irrelevant,'” said Alon, who studies lifespan at the Weizmann Institute of Science in Israel. “But we have a predetermined genetic lifespan in our genes.” However, genes don’t tell the whole story.

People still have some control over their lifespan

Although 55% of the lifespan is defined, the remaining 45% is up in the air. “Part of it was luck, and part of it was our decision,” Alon said.

According to Alon, these lifestyle choices – like exercise, diet and social connections – can change a person’s genetically influenced age by about five years. “Genetics is not a settled matter.”

A person genetically predetermined to live 80 years could reach 85 with healthy habits, while unhealthy lifestyle choices can reduce that expectancy to 75.

“But healthy habits won’t take you from 80 to 100 if your genetics are 80,” he said.

Life expectancy in the United States reached a record high of 79 years in 2024, according to data released this week by the U.S. Centers for Disease Control and Prevention. It trended upward for decades before falling almost a year and a half around the Covid-19 pandemic.

That’s why Kado says products marketed to improve longevity are not the answer to living longer. Instead, it comes down to exercise, diet, and social connections.

Genes that determine genetic potential

Although some genes have been identified as protective or harmful when it comes to aging, Kado says traits like longevity are much more complicated than a few genetic factors.

“There is no single gene,” Kado said. “Biology is complicated” – so complex that she says many of the elements that go into determining age are still unknown.

But as scientists learn more about the building blocks of biological age, tools could help target the pathways that shorten lifespan.

“If you know the genes, you know the mechanism,” Alon said. “And if you know the mechanism, you can intervene – you can make drugs. » According to him, this can be done instead of targeting one disease at a time.

This kind of future, however, is not yet possible decades from now. Genetic screening for conditions such as bipolar disorder and kidney disease reveals hereditary risks, but no test reliably predicts genetic age. Developing such a tool, Alon adds, would be the first step toward improving genetic lifespan.

What is more important: health or age?

Dan Arking, who studies aging at Johns Hopkins University, says the study sheds light on another important debate among scientists: how to weigh the benefits of years lived in good health versus the total number of years lived.

“If you can be healthier longer, that to me has enormous value,” Arking said, arguing that living longer may not be worth it if those years are spent in poor health.

Arking says reducing the risk of age-related diseases like osteoporosis can extend the number of years lived in good health. However, it is difficult to improve the lifespan. And it is unclear whether lifespan can be extended beyond 122 years, the highest age recorded.

“Once you get to a certain point, things stop,” Arking added. “There may be an upper limit.”

Alon also prioritizes quality of life over age, noting that over the past 150 years, average life expectancy has doubled but maximum lifespan has barely budged. In fact, mortality among centenarians has not improved over the past 30 years.

“Once we get close to 100, we already feel the wall of 120,” Alon explained. “I think this will require much more drastic measures, which are also very dangerous.”

Despite the ongoing debate, Alon says the study is a step in the right direction. It aims to reestablish the role of genetics in longevity – and could spark similar research in the future.

“Our study will be an additional motivation to carry out these future genetic studies,” he said. “It’s 50% nature and 50% nurture. We’re used to that concept. And now we know longevity is the same.”

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