Scientists have long believed that lifestyle choices play the leading role in determining how long people live. However, new research suggests that genetic longevity may be far more influential than previously assumed, reshaping how scientists understand aging and lifespan.
A major study published Thursday in the journal Science reports that genetics account for roughly 55% of the variation in human lifespan. This estimate is about twice as high as earlier calculations, which emphasized environmental factors such as diet, physical activity, and access to healthcare. Even so, experts say the findings align with what many people observe within their own families.
Dr. Deborah Kado, co-director of the Stanford Longevity Center, said the results are unsurprising. While she was not involved in the research, she noted that most human traits arise from a balance between biology and environment. Lifespan, she said, is no exception, even if its genetic contribution was previously underestimated.
Genetic Longevity Emerges as a Dominant Factor
The new findings suggest that genetic longevity functions like other complex traits, including cholesterol levels or osteoporosis risk. These traits arise from the combined influence of many genes, yet they are also shaped by daily behavior and living conditions.
Earlier studies minimized the role of genetics because they relied heavily on data from people born before the 19th century. During that era, infectious diseases, unsafe working conditions, and limited medical care caused many deaths at younger ages. As a result, environmental hazards overwhelmed genetic influences.
Uri Alon, the study’s lead author and a lifespan researcher at Israel’s Weizmann Institute of Science, explained that modern data allows scientists to isolate genetic effects more accurately. By removing deaths caused by preventable infections and accidents, the researchers found that genetic signals became much clearer.
According to Alon, this shift challenges the long-held assumption that genes barely matter for lifespan. Instead, he says, humans appear to have a genetically influenced age range that sets the framework for how long they might live.
Lifestyle Still Shapes Outcomes Alongside Genes
Although genetics account for more than half of lifespan variation, lifestyle choices remain significant. The study estimates that about 45% of lifespan differences stem from non-genetic factors, including behavior, environment, and chance.
Alon emphasized that genetic longevity is not fixed destiny. Healthy habits such as regular exercise, balanced nutrition, and strong social connections can still shift outcomes by several years. He estimates that lifestyle choices can move a person’s lifespan up or down by about five years relative to their genetic baseline.
For example, someone genetically predisposed to live to 80 could reach their mid-80s with consistent healthy behaviors. Conversely, poor lifestyle choices may shorten that expectancy into the mid-70s. Still, Alon cautioned that lifestyle alone cannot overcome genetic limits entirely.
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Genetic Longevity and Modern Life Expectancy Trends
The findings arrive as life expectancy in the United States reached a record high of 79 years in 2024, according to new data from the Centers for Disease Control and Prevention. That figure reflects decades of gradual improvement, interrupted briefly by declines during the Covid-19 pandemic.
Experts say these gains largely reflect improvements in public health, medical treatment, and safety standards rather than changes in genetic longevity. As a result, average lifespan has increased dramatically over the past 150 years, while the maximum human lifespan has barely changed.
Dr. Kado cautioned against viewing longevity-enhancing products as solutions. Instead, she stressed that proven habits such as physical activity, healthy diets, and social engagement remain the most reliable ways to improve quality of life within one’s genetic limits.
The Complexity Behind Genetic Longevity
While some genes have been linked to slower aging or higher disease risk, scientists agree that genetic longevity does not depend on a single gene. Instead, it emerges from thousands of genetic variants interacting with biological systems in complex ways.
Kado noted that many components influencing aging remain poorly understood. Biological age, she explained, reflects processes that science has only begun to map. Even so, understanding genetic mechanisms could eventually help researchers target pathways that accelerate aging.
Alon believes that identifying these pathways may open the door to new medical interventions. Rather than treating diseases one at a time, future therapies could aim to slow the biological processes that shorten lifespan. However, he acknowledged that such advances remain decades away.
Healthspan Versus Lifespan in Aging Research
The study also highlights an ongoing debate in aging research: whether extending life should matter more than extending healthy years. Dan Arking, an aging researcher at Johns Hopkins University, argues that healthspan deserves greater attention.
According to Arking, adding years of good health has greater value than merely increasing total lifespan. Reducing age-related diseases such as osteoporosis or cardiovascular conditions may allow people to remain active and independent for longer periods.
While average life expectancy has doubled since the 19th century, the maximum recorded human lifespan remains around 122 years. Arking said it remains unclear whether biology allows humans to live much longer than that.
Alon echoed this view, noting that survival rates among centenarians have not improved significantly in recent decades. He suggested that pushing beyond current limits may require extreme interventions with serious risks.
Despite these uncertainties, researchers say the study marks an important step. By reaffirming the role of genetic longevity, it encourages further investigation into how genes and environment interact to shape the human lifespan.
