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Scientists say they’ve found a big predictor of how long you’ll live.
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The data suggest that genetics may be the biggest influence on lifespan.
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Experts point out that a healthy lifestyle still matters.
Lifestyle factors play an important role in living a long and healthy life, but scientists say new research may have found an important indicator of how long you’ll live.
The study, which was published in the journal Science, analyzed life span and genetics in individual sets of identical and fraternal twins from Denmark, Sweden, and the USA. They then compared how well these factors matched across multiple sets of twins.
Because older records did not clearly indicate what people were dying from, researchers had to estimate which deaths were caused by external factors (such as accidents or disease) and separate them from natural, internal causes. The researchers found that death rates remained constant between the ages of 20 and 40, then rose rapidly as people aged. Additionally, deaths from external factors increase with age, but more slowly than deaths from internal factors such as aging or genetics.
After analyzing the data, the researchers found that genes can determine up to 55 percent of your life span—more than double previous estimates. The rest of your life likely comes from environmental influences, such as lifestyle and access to healthcare, along with random changes and changes in your genes, the researchers said.
Ben Shenhar, lead author of the study and a researcher on the physics of aging at the Weizmann Institute of Science in Rehovot, Israel, says the researcher discovered this by chance while playing with a mathematical model.
Meet the experts: Leonard E. Egede, MD, chair of the Department of Medicine at the University at Buffalo, Jacobs School of Medicine and Biomedical Sciences; Ben Shenhar, the study’s lead author and a physics of aging researcher at the Weizmann Institute of Science in Rehovot, Israel; Janet O’Mahony, MD, 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 extend their lives, but experts say that’s not the case. Here’s why.
Why do genes matter so much?
There are several reasons for this. “A big part of it is the risk of disease,” says Shenhar. “We include an analysis of the heritability of dying from cancer vs. cardiovascular disease vs. dementia. Death from dementia is the most heritable, then cardiovascular, and finally cancer.”
Twin studies show that genetics is responsible for about half of the variation in almost all human traits, including personality traits, Shenhar says. “In this sense, life span is not an outlier, but rather fits within 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 don’t work in isolation,” she says. “They establish 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 in other populations, points out Leonard E. Egede, MD, 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 suggests that all the time you spent eating healthy and going to the gym isn’t that important. Experts say that’s not true. “Longevity is a combination of genes, lifestyle and environmental factors,” says Dr. Egede.
Plus, even if lifespan is about 50 percent due to genetics, that leaves another 50 percent that’s due to other things, Shenhar says. “That’s where all the usual suspects come into play—exercise, diet, social relationships, environment, and so on,” he says.
Dr. Egede agrees. “Poor lifestyle is still an important factor in morbidity and mortality,” he says. “Healthy diet, moderate exercise, stress management and not smoking are key lifestyle changes that should continue to be encouraged.”
Following a healthy lifestyle is probably even more important as you age, says Shenhar. “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 for 80-year-olds. Our environment and lifestyle become increasingly important to our health and survival as we age.”
It’s also essential to visit your doctor regularly to stay on top of any health conditions that may arise, whether due to genetics or your lifestyle, says Janet O’Mahony, MD, 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 screenings like mammograms and colonoscopies also feels like a lifesaver.”
While genes set the stage, lifestyle factors also play an important role in your health outcomes. “Even when genetic contributions to lifespan are significant – up to half according to this research – lifestyle factors remain critically importantespecially for health span, meaning years lived in good physical and cognitive health,” says Frame. “In practical terms, lifestyle choices can either amplify genetic vulnerabilities or protect against them. While healthy behaviors may not completely override genetics, they strongly influence how well people age and how long they live free of disease and disability.”
The bottom line
Shenhar emphasizes that you shouldn’t throw in the towel on making healthy life choices based on these findings. “The message shouldn’t be 100 percent one of genetic determinism,” he says. “I don’t think there are any immediate implications on the personal level of making decisions about how to live one’s life.”
But Shenhar says the study suggests 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 allow 20 percent of centenarians to reach the age of 100 without any serious illness, for example, then we hope that in the future it could better guide and inform research into longevity drugs and interventions,” he says.
Until then, Dr. Egede recommends sticking with lifestyles that have been proven to support health. “You can’t control your genes, but you can change your lifestyle,” he says. “Focus on lifestyle modification.”
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