Wedoany.com Report on Feb 10th, A new study published in the journal Science reveals that the influence of genes on human lifespan may far exceed previous understanding. Traditionally, it was believed that genes contributed only 20-25% to lifespan variation. However, this new research, analyzing data from Scandinavian twins, twins reared apart in the US, and relatives of centenarians, found that after excluding external causes of death such as accidents and infections, the genetic contribution rate could rise to 50-55%.
The researchers point out that this change stems from the evolution of causes of death: a century ago, external threats like accidents and infections were the main killers; today, in developed countries, aging and related diseases dominate. As the environment improves, the impact of genes on lifespan becomes more prominent. For example, genetic factors have a significant influence on dementia risk, a moderate effect on heart disease, and are relatively mild in cancer.
The study emphasizes that the increase in genetic contribution is not because genes themselves have become stronger, but because the influence of environmental factors has weakened. Using height as an example, when nutritional differences shrink, genetic differences become the main cause of the remaining variation. Similarly, widespread vaccination, reduced pollution, and the promotion of healthy lifestyles have lowered environmental variation, causing the proportion of heritability to naturally rise due to mathematical calculation.
Heritability is not a fixed attribute but a measure that varies with population and environment. The traditional 20-25% reflects a historical environment with high external threats, while 50-55% corresponds to a scenario where external threats are largely eliminated. "50% heritability" of lifespan does not mean genes determine half of an individual's life chances; the actual contribution varies from person to person, depending on environmental interactions.
Pathways to longevity are diverse: some people rely on favorable genes to resist risks, while others compensate for genetic shortcomings through good nutrition, exercise, and medical care. The combination depends on the living conditions of the population. The study authors stated that about half of lifespan variation is still influenced by environment, lifestyle, medical care, and random biological processes, and future research needs to delve deeper into the interaction mechanisms between genes and environment.
This research was conducted by a team led by Associate Professor Karin Modig in epidemiology at the Karolinska Institute and is republished from The Conversation. It deepens our understanding of the determinants of lifespan, highlighting the importance of the combined effect of genes and environment, rather than providing a single answer.
