Genetics Play a Key Role in Human Longevity
In a recent study, researchers have found that genetics significantly contribute to how long people live. While various factors, including diet, exercise, environment, and lifestyle choices like smoking and drinking, influence lifespan, it seems genes might play an even larger role than we previously thought. This new research estimates the genetic contribution to lifespan at nearly 50%, which is about double previous estimates. It’s a finding that aligns with similar studies conducted on laboratory animals.
Ben Shenhar, a doctoral student in physics at the Weizmann Institute of Science in Israel, who led the study, noted that numerous elements shape lifespan. He emphasized the influence of randomness, particularly when looking at genetically identical organisms in similar environments that still experience different lifespans. “In our work, we aimed to clarify how much of the variability in lifespan among individuals can be attributed to genetics, separating it from other factors, which collectively also represent around 50%,” he explained.
The researchers took a closer look at previous twin studies from Sweden and Denmark, primarily dating back to the 19th century. These earlier studies often overlooked deaths from violence, accidents, infectious diseases, and other external factors—referred to as extrinsic mortality—which they argue skewed the understanding of genetics in longevity.
The historical data available typically recorded just the age at death, without indicating the cause. For example, if one twin passed away at 90 from natural causes while the other died at 30 from an infectious disease, this lack of detail may lead to misleading interpretations regarding genetic influences on lifespan.
Shenhar mentioned that extrinsic mortality during the period when the twins were studied was significantly higher, about ten times more than what we see today, largely due to infectious diseases that are now commonly treated.
To address these gaps, the study utilized a mathematical approach to factor in extrinsic mortality among twins. By analyzing newer data from Sweden, which included both twins raised together and apart, the researchers confirmed that as extrinsic mortality decreases, the heritability of lifespan increases.
Shenhar also pointed out the value of studying identical twins raised in different environments to distinguish genetic factors from environmental ones. Fraternal twins add another layer, sharing around half their genetic material, which makes them useful for this kind of research.
“Earlier twin studies applied statistical methods that fit well for traits like height and blood pressure—things not heavily influenced by extrinsic mortality,” noted Uri Alon, a systems biologist at the Weizmann Institute and a senior author of the study. “But lifespan is uniquely affected by extrinsic factors, and previous studies didn’t account for causes of death.”
The findings could have significant implications for aging research. Shenhar suggested that the earlier low estimates of heritability might have hindered funding and research into the genetics of aging, leading to the assumption that age-related traits were largely random or environmental. However, their work reveals a strong genetic component that was previously obscured by the “noise” in the data.
Interestingly, the influence of genes on lifespan is dual-faceted. Some genetic factors predispose individuals to diseases that can shorten lifespan, while others appear to offer protective benefits, such as those seen in centenarians who often reach 100 without severe medical conditions. “Clearly, these individuals possess protective genes that fend off diseases typically associated with aging,” Shenhar remarked, adding that while some longevity-related genes have been identified, it’s likely that hundreds, if not thousands, of genes play a role.
