A groundbreaking new study reveals that genetics play a significantly larger role in determining human lifespan than previously estimated. Researchers now suggest that approximately 50% of how long a person lives is influenced by their genes, more than doubling prior assessments. This finding reshapes our understanding of longevity and has critical implications for future medical research, particularly in an era of rapidly aging populations.
Rethinking the Role of Genetics
For decades, estimates of lifespan heritability have hovered between 6% and 25%. These lower figures were calculated using twin studies, comparing lifespan correlations between identical (sharing nearly 100% DNA) and fraternal (sharing 50% DNA) twins. However, these studies struggled to separate genetic factors from external causes of death, such as accidents or treatable infections.
The latest research, published in Science, employs a novel mathematical model to circumvent this issue. By accounting for external mortality factors, even in cases where specific causes of death are unknown, the team consistently found a heritability rate of around 50% across datasets from Sweden, Denmark, and the U.S. The data included individuals born between 1870 and 1935, providing a historical perspective on longevity trends.
How the Model Works
The research team, composed of geneticists, physicians, and statisticians, designed the model to mathematically filter out extrinsic influences. The model’s key innovation is its ability to estimate heritability regardless of how environmental factors change over time. Previous lifespan estimates would have increased as external factors decreased, but this model provided a constant estimate of heritability.
“Previously, when we studied lifespan and predictors, we tended to use all-cause mortality, where we’re just looking at what age people died and not really considering what the causes are — cause of death is often missing [from those records],” explains Luke Pilling, a geneticist not involved in the study. The new model corrects for this deficiency.
Implications for Aging Populations
The implications for geriatric medicine are significant. As more nations grapple with aging populations, understanding the genetic underpinnings of longevity could lead to interventions that promote both lifespan and healthspan — the period of life spent in good health.
“If we understand the biological mechanisms that cause people to live longer and healthier, we can perhaps design interventions to promote those pathways and to promote health span,” Pilling stated. Identifying the genetic markers associated with longevity could pave the way for targeted therapies and lifestyle recommendations.
Caveats and Future Research
Despite its rigor, the study acknowledges limitations. The model has been primarily tested on people of Northern European descent due to data availability. Further research is needed to determine whether these findings apply universally. Additionally, the ideal scenario would involve complete cause-of-death records, which remain elusive for many historical datasets.
“What it shows is that you have a certain propensity to become long-lived which is in your genes, and the rest is based on what you do and where you live,” said study co-author Joris Deelen. “Environment is still super important, and people should try to optimize their lifestyle as much as they can.”
Ultimately, this study underscores the profound influence of genetics on human longevity while reinforcing the importance of lifestyle and environmental factors. The 50% heritability estimate does not determine fate; it clarifies the genetic predisposition toward a longer life, which can be further influenced by individual choices and societal conditions.
