They squint in exasperation, crumple in disgust, and deepen with joy. Theyโ€™re teeny โ€” less than a centimeter wide โ€” but they can be a source of endless frustration or a point of pride. Theyโ€™re the result of a muscle twitch thatโ€™s as uncontrollable as it is fleeting, but whether theyโ€™ve sent us to the dermatologist in a panic or reminded us of our motherโ€™s laugh, theyโ€™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 crowโ€™s-feet. And theyโ€™re more complicated, more nuanced, than we ever thought.