Fasting, hard training, or blood transfusions: there are plenty of more or less extreme tricks to live as long as possible. But the scope for how much we can influence our lifespan by lifestyle seems to be considerably smaller than we thought.
Now that the researchers have analyzed data from twin registries in Sweden and Denmark and from centenarians in the United States, a new picture emerges. After excluding deaths caused by external factors such as accidents or infectious diseases, longevity is 50 percent explained by genes.
Big change
Until now, we have said that between 10 and 30 percent of lifespan is determined by genes, so it is a big change, says Sara Hägg, associate professor of molecular epidemiology at Karolinska Institutet and co-author of the study.
She explains that the researchers have used new models that better distinguish the body's biological mechanisms from external ones. Through new estimation methods, a picture emerges in which genes have greater importance. Sara Hägg says that she was surprised there was such a large proportion, but that it is in line with heredity for several diseases.
Is there space?
Should we despair and think that it doesn't matter if we quit smoking or take an extra walk? No, absolutely not, according to Sara Hägg.
"50 percent is influenced by our lifestyle, so there's actually a lot we can influence. How long we live is influenced by a lot of factors," she says.
The researchers' findings, published in the journal Science, say nothing about the lifespan of individuals. But they hope that the results can lead us closer to the answer to which genes help control aging.
"Life expectancy is something that fascinates us because we all get older. So far, we know very little about which genes regulate aging," says Sara Hägg.
In Sweden, the average life expectancy in 2024 was 85.4 years for women and 82.3 years for men.
Historically, life expectancy in Sweden has increased significantly. This increase was largely due to a decrease in infant mortality.
For example, in the 1950s, average life expectancy, calculated from birth, was around 74 years for women and 71 years for men. Today, infant mortality is lower, and the increase in life expectancy is mainly due to reduced mortality at older ages.
In 2020, life expectancy fell unusually sharply because of many deaths attributed to COVID-19. Since then, life expectancy has returned to approximately the same levels as before the pandemic.
Source: Statistics Sweden
