When was the last time you dusted off your college yearbook? Pull it off the shelf for a minute—it can predict your own success (and your classmates’)!

In this study, researchers rated positive emotions (meaning the genuineness of their smiles) in 114 college yearbook photos from an all-women’s college. Next, they looked at how the same women fared over a 30-year follow-up.

Women who appeared genuinely happy in their yearbook photos were more likely to have better social and cognitive skills, fewer negative emotions, more satisfying marriages and better overall wellbeing across adulthood.

Just another reason to flash your pearly whites!