WASHINGTON, Jan 29 — How long we live feels like a lottery, doesn’t it? We obsess over kale smoothies, marathon training, and dodging secondhand smoke, but sometimes, despite our best efforts, life throws a curveball. But what if the biggest factor isn’t what we *do*, but who we *are*—down to the very code in our DNA?
Genetics May Play a Bigger Role in Lifespan Than Previously Thought
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A new study suggests our genes could account for roughly half of our lifespan, doubling previous estimates.
- A study published Thursday in the journal Science estimates genetics contribute approximately 50% to how long a person lives.
- Researchers corrected for “extrinsic mortality”—deaths from accidents, violence, and infectious disease—which skewed earlier twin studies.
- The findings validate the search for genetic factors influencing longevity, suggesting a strong genetic signal previously obscured by data limitations.
For decades, scientists have debated the relative contributions of genetics and environment to longevity. Now, a new study suggests our genes might have a far stronger influence than we realized—around 50 percent, a figure that roughly doubles previous research. This finding aligns with observations from lifespan studies in animals.
“Lifespan is undoubtedly shaped by many factors, including lifestyle, genes and, importantly, randomness—take for example genetically identical organisms raised in similar environments that die at different times,” explained Ben Shenhar, a doctoral student in physics at the Weizmann Institute of Science in Israel and lead author of the study. “In our work, we tried to give a handle on the amount of variance between different people that can be attributed to genetics. Our study tried to partition the longevity factors into genetics and ‘everything else.’ The ‘everything else’ is around 50 per cent of the pile.”
Correcting for Historical Data Limitations
The researchers revisited data from earlier twin studies, primarily focusing on Swedish and Danish twins from the 19th century. These studies, they argued, didn’t adequately account for “extrinsic mortality”—deaths caused by external factors like violence, accidents, and infectious diseases. This oversight, they believe, underestimated the role of genetics.
Historical data often lacked information about the *cause* of death, only recording the age at which someone died. This creates a problem: if one twin dies at 90 from natural causes, while the other dies at 30 from typhus, simply knowing the ages doesn’t reveal the impact of heredity.
A: Failing to account for deaths from external factors like infectious diseases in historical data can significantly underestimate the genetic contribution to longevity, making it appear as though lifestyle and environment play a larger role than they actually do.
To address this, the team developed a mathematical formula to account for extrinsic mortality. Shenhar noted that extrinsic mortality rates were significantly higher in the past—roughly ten times higher than today—primarily due to infectious diseases now easily treated with antibiotics.
They then validated their approach using more recent Swedish twin data, including twins raised together and apart. The analysis confirmed that as extrinsic mortality declines, the heritability of lifespan increases.
Nature vs. Nurture: Untangling the Genetic Influence
“Identical twins raised apart share their genes, but not their environment. This helps tease apart genetics from the environment, nature from nurture,” said Uri Alon, a systems biologist at the Weizmann Institute and senior author of the study.
Fraternal twins, who share about half their genetic makeup, also proved valuable in the research. Alon explained that previous statistical methods used in twin studies were well-suited for traits like height or blood pressure, which aren’t significantly affected by extrinsic mortality. However, lifespan is uniquely vulnerable to these external factors.
“But mean lifespan is the one special trait that is strongly affected by extrinsic mortality. Since cause of death was not recorded for the classical twin studies, it was not corrected for,” Alon said.
Implications for Aging Research
These findings could have significant implications for aging research. Shenhar suggested that previous underestimates of genetic influence may have discouraged funding and investigation into the genetics of longevity. “Our work validates the search for genetic factors of longevity, showing that the genetic signal is strong but was previously hidden by ‘noise’ in the data,” he said.
Genes influence lifespan in both positive and negative ways. Some genetic defects can lead to disease and shorten life expectancy, while others appear to offer protection against age-related illnesses. “Many centenarians reach age 100 without any serious medical conditions,” Shenhar said. “It’s clear that these people have protective genes which guard against developing diseases which naturally occur with age. Some of these genes have been identified, although like most complex traits longevity is likely impacted by hundreds if not thousands of genes.”
What do you think? Does this new research change how you view the factors influencing a long life? Share your thoughts in the comments below.
