Study finds genetic contribution to human lifespan is about 50% – more than double previous estimates
What determines how long we live – and to what extent is our lifespan shaped by our genes? Surprisingly, scientists believed for decades that the heritability of human lifespan was relatively low compared to other human traits, standing at just 20 to 25%; some recent large-scale studies even placed it below 10%. Now, a new study from the Weizmann Institute of Science, published in Science, presents an entirely different picture. According to the findings, genetics accounts for about 50% of variation in human lifespan – twice as much, or more, than previously thought.
The study was led by Ben Shenhar from the lab of Prof Uri Alon of Weizmann’s Molecular Cell Biology Department.
“For many years, lifespan was attributed mainly to non-genetic factors, fuelling scepticism about genetic determinants of longevity”
Using mathematical models and analyses of three large twin databases from Sweden and Denmark – including, for the first time in this context, a dataset of twins who were raised apart – the researchers showed that earlier heritability estimates were masked by high levels of extrinsic mortality, such as deaths caused by accidents, infections and environmental hazards. Filtering out such extrinsic factors was impossible in historic datasets because they provided no information about the cause of death. To compensate for this limitation, the researchers developed an innovative framework that included mathematical simulation of virtual twins to separate deaths due to biological ageing from those caused by extrinsic factors. The new results are consistent with the heritability of other complex human traits and with findings from animal models.
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Up to age 80, the risk of dying from dementia shows a heritability of about 70% – far higher than that of cancer or heart disease.
The results have far-reaching implications for ageing research and public health. “For many years, human lifespan was thought to be shaped almost entirely by non-genetic factors, which led to considerable scepticism about the role of genetics in ageing and about the feasibility of identifying genetic determinants of longevity,” says Shenhar. “By contrast, if heritability is high, as we have shown, this creates an incentive to search for gene variants that extend lifespan, in order to understand the biology of ageing and, potentially, to address it therapeutically.”
Source: Weizmann Institute of Science
