There’s a link between more education and a richer, healthier life. This isn’t just conventional wisdom: it has been repeatedly established by research study after research study.

But how does this link work? Does education itself cause the boost in health—perhaps by making people richer? Do healthier children get ahead in school? Or does some other cause, like a wealthy background or greater cognitive ability, make people both more educated and healthier?

It’s a complicated question to untangle, but a paper in Nature Human Behaviour this week uses data from a natural experiment to get some answers. They found that, regardless of their economic status, teenagers who were forced to stay in school a bit longer because of legal changes were healthier in later life than similar teenagers who only just missed the new regulations.