They squint in exasperation, crumple in disgust, and deepen with joy. They’re teeny — less than a centimeter wide — but they can be a source of endless frustration or a point of pride. They’re the result of a muscle twitch that’s as uncontrollable as it is fleeting, but whether they’ve sent us to the dermatologist in a panic or reminded us of our mother’s laugh, they’re part of who we are.

They go by unpronounceable names (orbicularis oculi contractions) and cryptic ones (Duchenne markers). But the most common, the most weighted, is crow’s-feet. And they’re more complicated, more nuanced, than we ever thought.