Human life span found to be far more heritable than previously believed

New analysis of twin studies suggests that genetics may play a significantly larger role in determining human lifespan than previously understood. Researchers found that when accounting for deaths caused by external factors—such as accidents and infectious diseases—genetics may explain approximately 50% of the variation in how long people live.

Unraveling the Genetic Influence on Longevity

Understanding the heritability of human lifespan has long been a challenge in aging research. While some genes have been linked to longevity, external environmental factors often obscure the potential genetic contributions. Previous studies have yielded varying estimates of life-span heritability, leading to skepticism about the role of genetics.

Did You Know? The study, published in Science, used mathematical models, simulations, and large-scale twin cohort datasets to disentangle intrinsic and extrinsic sources of death.

According to Ben Shenhar and colleagues, discrepancies in previous research may stem from an underestimation of “extrinsic” mortality—deaths due to external causes. These external factors can dilute the measurable impact of genetics, which primarily influences “intrinsic” mortality, driven by aging and internal biological decline.

A Dramatic Shift in Estimates

The analysis conducted by Shenhar et al. revealed that extrinsic mortality systematically underestimates life-span heritability. Once deaths from external causes are properly accounted for, the genetic contribution to human life span rises dramatically to roughly 55%, more than double previous estimates. This revised estimate aligns human life span with the heritability observed in laboratory mice and most other complex physiological traits.

Expert Insight: A substantial genetic contribution strengthens the rationale for large-scale efforts to identify longevity-associated variants, refine polygenic risk scores, and link genetic differences to specific biological pathways that regulate aging.

Daniela Bakula and Morten Scheibye-Knudsen note that this study has “important consequences for aging research.”

Frequently Asked Questions

What is intrinsic mortality?

Intrinsic mortality is death driven by aging and internal biological decline.

What is extrinsic mortality?

Extrinsic mortality refers to deaths due to external causes, such as accidents or infectious disease.

What did the study by Shenhar et al. find?

Shenhar et al. found that the genetic contribution to human life span rises to roughly 55% when deaths from external causes are accounted for, more than double previous estimates.

As research continues, it may be possible to identify specific genetic variants associated with longevity and to develop interventions that target the biological pathways regulating aging. However, further study is needed to fully understand the complex interplay between genetics and environment in determining human lifespan.