Genetics May Hold the Key to 50% of Human Lifespan Variation
Scientists have uncovered compelling evidence that genetics could be responsible for approximately half of the variation in human lifespan, according to a groundbreaking new study. This research challenges previous estimates and offers fresh insights into the complex interplay between genes and longevity.
Unmasking the True Genetic Contribution
Previous investigations into the genetic component of human lifespan have produced widely varying results, with heritability estimates ranging from just 6% to 33%. However, Professor Uri Alon and his colleagues at the Weizmann Institute of Science in Israel argue that these figures significantly underestimate the true genetic influence.
The research team developed an innovative mathematical model that accounts for extrinsic mortality – factors such as accidents, infectious diseases, and other external causes that can shorten lives. By calibrating their model using historical datasets from thousands of twin pairs in Denmark and Sweden, they were able to isolate the signal from biological ageing, which is fundamentally driven by genetics.
The 50% Genetic Factor
The findings suggest that genetics accounts for about 50% of the variation in human lifespan, a figure comparable to that observed in laboratory studies of wild mice. The remaining 50% is likely influenced by a combination of environmental factors, lifestyle choices, and random biological effects.
Professor Uri Alon expressed hope that this discovery would inspire further investigation into the specific genes that impact lifespan. He noted: "These genes will tell us the mechanisms that govern our internal clocks. These can one day be turned into therapy to slow down the rate of ageing and in that way slow down all age-related disease at once."
Environmental Factors and Protective Genes
Co-author Ben Shenhar emphasised that lifestyle and environmental influences become increasingly important as we age. He explained: "That's where we would expect to find all the usual suspects – lifestyle, diet, exercise, social relations, environment, and more."
The study also revealed intriguing patterns among centenarians. Shenhar observed: "Around 20% of centenarians, for example, reach age 100 without any serious debilitating illnesses," suggesting that certain genes may offer protective effects against age-related diseases.
Validation and Future Implications
The research team validated their findings using data from a US study of siblings of centenarians, which similarly indicated a heritability of lifespan around 50%. Further analysis of Swedish datasets showed that as extrinsic mortality decreased throughout the 20th century – likely due to public health improvements – the estimated genetic contribution to lifespan increased correspondingly.
Professor Richard Faragher of the University of Brighton commented that the study suggests humans are not outliers in terms of lifespan heritability compared to other species. This similarity provides confidence that ageing interventions successful in laboratory animals might eventually translate to human applications.
The research represents a significant step forward in understanding the genetic foundations of human longevity, potentially paving the way for future therapeutic approaches to extend healthy lifespan and combat age-related diseases.
