Long life may be largely determined by genetics

A Science paper, reported in The Guardian, used a model that adjusts for deaths from external causes and, based on historical twin data from Denmark and Sweden, suggests genetics may account for about 50% of variation in human lifespan.

Researchers published a study in Science that revises estimates of how much genetics contributes to human lifespan. The work responds to past analyses that did not separate deaths caused by external events from deaths driven by internal biological ageing. The team, including Prof Uri Alon of the Weizmann Institute, built a mathematical model to remove the impact of external causes of death. They calibrated that model using correlations from thousands of twin pairs in Denmark and Sweden. Key findings: - The analysis explicitly adjusts for "extrinsic mortality," meaning deaths caused by accidents, infections or other external factors, which earlier studies did not fully separate from biological ageing. - After removing the effect of extrinsic mortality, the researchers report genetics may explain about 50% of the variation in human lifespan. - Earlier heritability estimates for lifespan ranged from about 6% to 33%, and the authors say those figures underestimated genetic contribution because they did not account for external causes of death. - The study attributes the remaining variation to random biological effects and environmental influences. - Prof Uri Alon was quoted as saying he hopes the results will prompt deeper searches for genes that affect ageing and that those genes could reveal mechanisms relevant to therapies. Summary: The study increases the estimated share of lifespan variation linked to genetics by separating external causes of death from internal ageing processes. The authors and coverage indicate the work could steer further genetic research on ageing. Undetermined at this time.