- Scientists say they have found a big indicator of how long you’ll live.
- The data suggest that genetics may be the biggest influence on lifespan.
- Experts stress that a healthy lifestyle still matters.
Lifestyle factors play a large role in living a long and healthy life, but scientists say new research may have found a big indicator of how long you’ll live.
The study, which was published in the journal Science, analyzed lifespan and genetics in individual sets of identical and fraternal twins across Denmark, Sweden, and the U.S. They then compared how well those factors matched across many sets of twins.
Because older records didn’t clearly state what people died from, the researchers had to estimate which deaths were caused by outside factors (like accidents or disease) and separate them from natural, internal causes. Researchers found that death rates stayed steady between ages 20 and 40, then increased quickly as people aged. Evenmore, deaths caused by outside factors rise with age, but more slowly than deaths caused by internal factors like aging or genetics.
After crunching the data, the researchers found that genes may determine up to 55% of your lifespan—more than double previous estimates. The rest of your lifespan likely stems from environmental influences like lifestyle and healthcare access, along with random changes and modifications to your genes, the researchers said.
Ben Shenhar, lead study author and researcher on the physics of aging at the Weizmann Institute of Science in Rehovot, Israel, says the researcher discovered this by chance while tinkering with a mathematical model.
Meet the experts: Leonard E. Egede, M.D., chair of the Department of Medicine at the University at Buffalo, Jacobs School of Medicine and Biomedical Sciences; Ben Shenhar, lead study author and researcher on the physics of aging at the Weizmann Institute of Science in Rehovot, Israel; Janet O’Mahony, M.D., internist at Mercy Medical Center in Baltimore, MD; Leigh Frame, Ph.D., executive director of the Office of Integrative Medicine and Health at George Washington University
The findings sound like bad news for those looking for actionable ways to help prolong their life, but experts say that’s not the case. Here’s why.
Why do genes matter so much?
There are several reasons for this. “Much of it is disease risk,” Shenhar says. “We include an analysis of heritability to die from cancer vs. cardiovascular disease vs dementia. Death from dementia is most heritable, then cardiovascular, and finally cancer.”
Twin studies show that genetics is responsible for about half of the variance in almost all human traits, including personality traits, Shenhar says. “In that sense, lifespan is not an outlier—rather, it falls within the fold of what we already know about genetic influence,” he says.
But Shenhar notes that one or two genes don’t tell the whole story. “Lifespan…is influenced by hundreds, if not thousands, of genes—not a select few,” he says.
Genes also don’t tell the whole story, according to Leigh Frame, Ph.D., executive director of the Office of Integrative Medicine and Health at George Washington University. “Genes do not operate in isolation,” she says. “They set a range of possibilities rather than a fixed outcome, influencing how individuals respond to environmental exposures, lifestyle behaviors, and aging itself.”
The study isn’t perfect: It used a Scandinavian twin registry, which means the results may not apply to people from other populations, points out Leonard E. Egede, M.D., chair of the Department of Medicine at the University at Buffalo, Jacobs School of Medicine and Biomedical Sciences.
What might this mean for lifestyle factors?
It’s easy to assume that the study is suggesting that all that time you’ve spent eating healthy and going to the gym isn’t all that important. Experts say that’s just not true. “Longevity is a combination of genes, lifestyle, and environmental factors,” Dr. Egede says.
Plus, even if lifespan is about 50% due to genetics, that still leaves an additional 50% that’s due to other things, Shenhar says. “That’s where all the usual suspects come in—exercise, diet, social relations, environment, and so on,” he says.
Dr. Egede agrees. “Poor lifestyle is still an important driver of morbidity and mortality,” he says. “Healthy diet, moderate exercise, stress management, and not smoking are key lifestyle modifications that should still be encouraged.”
Following a healthy lifestyle is likely even more important as you age, Shenhar says. “For example, there is not much difference in mortality between 30-year-olds who drink, smoke, and live wildly, and those who live well,” he says. “The opposite is true of 80-year-olds. Our environment and lifestyle become more and more important for our health and survival as we age.”
It’s also crucial to visit your doctor regularly to stay on top of any health conditions that may pop up, whether due to your genetics or lifestyle, says Janet O’Mahony, M.D., an internist at Mercy Medical Center in Baltimore, MD. “Access to quality primary care [may] diagnose and treat high blood pressure, diabetes, obesity, and high cholesterol,” she says. “Access to cancer screening tests like mammograms and colonoscopies is also felt to save lives.”
While genes lay the foundation, lifestyle factors play a big role in your health outcomes, too. “Even when genetic contributions to lifespan are significant—as much as half according to this research—lifestyle factors remain critically important, especially for healthspan, meaning the years lived in good physical and cognitive health,” Frame says. “In practical terms, lifestyle choices can either amplify genetic vulnerabilities or help buffer against them. While healthy behaviors may not override genetics entirely, they strongly influence how well people age and how long they live free from disease and disability.”
The bottom line
Shenhar stresses that you shouldn’t throw in the towel on making healthy lifestyle choices based on these findings. “The message should 100% not be one of genetic determinism,” he says. “I don’t think there are any immediate implications on the personal, decision-making level of how to live one’s life.”
But Shenhar says that the study suggests that we have a lot more to learn about the genetics of aging. “If we can understand what biological pathways underlie the favorable genetic profiles that enable 20% of centenarians to reach age 100 without any serious illnesses, for example, then that could hopefully in the future better guide and fuel research into longevity drugs and interventions,” he says.
Until then, Dr. Egede recommends sticking with the lifestyle choices that have been proven to support good health. “You can’t control your genes, but you can modify your lifestyle,” he says. “Focus on lifestyle modification.”
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