Some people who reach old age attribute it to healthy eating, others to their ability to avoid trouble, and still others to good genetics.
Scientists seem to have finally cracked the key secret to longevity: it’s genetics. According to new findings, genetics account for over 50 percent of the variations in lifespan.
A team of researchers from the Weizmann Institute of Science in Israel stated that previous studies attempting to identify the genetic component of longevity did not take into account what is known as “external mortality.” This refers to lives cut short by accidents, homicides, infectious diseases, or other factors arising outside the body. The threat of “external mortality” increases with age as people become more vulnerable.
According to the scientists, this has masked the genetic contribution to human lifespan. In their study, the team focused on examining “heritability”—the proportion of variation in traits that can be considered genetic rather than environmental, such as height, body mass, or .
What Did the Scientists Discover?
Previous studies on human lifespan showed a wide range of heritability values, varying from 6 to 33 percent. However, the researchers claimed these figures were underestimated, as reported by The Guardian.
“I hope this inspires researchers to delve deeper into that influence lifespan. These genes will tell us about the mechanisms that govern our internal clock. In the future, they could be used in therapies that slow down the aging process, thereby delaying the onset of all age-related diseases simultaneously,” said Professor Uri Alon, the senior author of the study.
The scientists developed a mathematical model that accounts for external mortality and the impact of biological , calibrating it using the correlation of lifespan from historical datasets of thousands of twin pairs from Denmark and Sweden.
To detect signals from biological aging driven by genetic factors, the team excluded the influence of external mortality. The results, published in the journal Science, confirmed that 50-55 percent of the variations in human lifespan are attributable to genetics. According to the researchers, this figure is comparable to those observed in wild mice under laboratory conditions.
The remaining variations in human lifespan, the researchers noted, can likely be explained by factors such as random biological effects and environmental influences.
“This is where we expect to find all the usual factors—, diet, , social relationships, the environment, and much more,” said Ben Shenhar, the lead author of the study. He added that the impact of lifestyle and environment becomes increasingly significant with age.
The research team also validated their findings using data from an American study of siblings of . In this case, the heritability of lifespan was also found to be over 50 percent.
Meanwhile, an analysis of another Swedish dataset showed that as external mortality decreased since the early 20th century (likely due to improvements in public health), the predicted genetic contribution to lifespan increased. This supports the theory that external mortality is a key factor. The team also discovered that the heritability of lifespan varies depending on the cause of death, such as cancer, dementia, and age.
According to Ben Shenhar, the significant role of genetics in longevity is evident in everyday experience. “For instance, about 20 percent of centenarians live to 100 years without any serious debilitating diseases, which may indicate a protective effect of their genes. Many of these have already been identified by researchers, but there is still much to discover,” he said.
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