A new study suggests that genetics may play a much larger role in human lifespan than previously believed, with researchers estimating that genes account for roughly 50% of how long people live — about double earlier estimates.
The research, led by Ben Shenhar, a doctoral student in physics at Israel’s Weizmann Institute of Science, was published in Science and highlights the influence of heredity alongside lifestyle, environment, and chance. Shenhar noted that even genetically identical individuals raised in similar conditions can die at very different ages, emphasizing the role of randomness.
The team addressed limitations in previous studies, which mostly analyzed 19th-century Swedish and Danish twins. These studies often ignored deaths caused by accidents, violence, and infectious diseases — known as extrinsic mortality — which could mask the true genetic contribution to lifespan.
By applying a mathematical formula to account for extrinsic deaths, and analyzing newer twin data from Sweden, the researchers found that as extrinsic mortality declines, the heritability of lifespan rises. Identical twins raised apart, as well as fraternal twins, provided insights into separating genetic influences from environmental ones.
“Low heritability estimates may have discouraged research into the genetics of aging,” Shenhar said. “Our work shows that the genetic signal is strong but was previously hidden by ‘noise’ in historical data.”
Genes can both shorten and extend lifespan. Some inherited defects may cause disease, while protective genes — found in many centenarians — guard against age-related conditions. According to the researchers, longevity is likely influenced by hundreds or even thousands of genes working together.
