Staying longer in school not only gives you a better education – it also means you're more likely to live longer, and see less wear and tear on your cells, according to a new analysis of data on 3,101 people across three generations.

Broadly speaking, more years in education mean a longer life, but we're still trying to understand why. The researchers from the US, Norway, and the UK wanted to look more closely at the relationship between schooling and health.

While it's generally accepted that better qualifications mean a better job and more money – which then means better access to healthcare and opportunities for living a healthier lifestyle – this new research suggests that at the cellular level, our bodies are likely to age slower if we've spent more time in school.

"We've known for a long time that people who have higher levels of education tend to live longer lives," says epidemiologist Daniel Belsky from Columbia University.

"But there are a bunch of challenges in figuring out how that happens and, critically, whether interventions to promote educational attainment will contribute to healthy longevity."

An extra two years of schooling equated to an average of 2-3 percent slower aging, the analysis showed. The data was taken from the ​​Framingham Heart Study, a research project that's been following a large group of the city's residents, and now some of their children and grandchildren, since 1948.

The researchers used an epigenetic clock algorithm on the data, designed to measure biological age through markers in DNA. When scientists talk about faster biological aging, it's not that our birthdays are coming around more quickly – it's that our cells are showing damage sooner.

Through cross-references between siblings, and between children and their parents, the researchers were able to isolate the effects education was having, to some extent. It's the first time education and biological aging have been linked in this way.

"A key confound in studies like these is that people with different levels of education tend to come from families with different educational backgrounds and different levels of other resources," says epidemiologist Gloria Graf from Columbia University.

To minimise these confounds, they looked at 'educational mobility' – how much education someone achieved compared to their parents, and compared to their siblings. This method helped account for differences within families to figure out more accurately how education impacts aging and longevity.

"We found that upward educational mobility was associated both with a slower pace of aging and decreased risk of death," says Graf.

The question of why exactly this is happening wasn't addressed in the study. It's certainly possible that the reasons are the same as those linking higher education with longer life: the ability to afford better healthcare and to access a healthier lifestyle.

Part of the reason for the study was to look into the benefits of promoting further education, and to explore ways of measuring its success in terms of keeping us healthier for longer – which these biological aging markers can now help with.

However, more research will be needed to know for sure how the association works. A number of other factors, including childhood poverty, are likely to have an impact both on mortality and how long someone spends in school.

"Ultimately, experimental evidence is needed to confirm our findings," says Belsky.

The research has been published in JAMA Network Open.