Are Smile Lines Attractive or Do They Make You Look Older?

Crow's feet are the fine radiating lines at the outer corners of the eyes that appear when the orbicularis oculi contracts during a genuine smile. They are the visual mark of a Duchenne smile — and research consistently shows they are read as positive signals rather than aging markers when they appear in the context of a smile.

A 2021 study by Hoehl and colleagues found that observers rated faces with crow's feet during smiling as significantly more genuine, trustworthy, and warm than the same faces without them. The lines themselves are not what drives the positive rating — it is what they signify: that the orbicularis oculi is firing, which means the smile is real.

At rest, crow's feet are simply fine lines — neither particularly positive nor negative. But in the context of a smile, they actively increase how genuine the expression reads. People who have developed crow's feet from years of genuine, frequent smiling often photograph exceptionally well because their smiles score high on the eye engagement component that most distinguishes authentic from posed expressions.

Nasolabial folds — the lines running from the sides of the nose down to the mouth corners — are a different story. They are primarily driven by facial volume loss and structural descent rather than muscle activation. As the malar fat pad deflates and descends with age, it creates a shadow and crease at the fold line. Deep nasolabial folds at rest are reliably associated with older perceived age.

Unlike crow's feet, nasolabial folds do not carry an authenticity signal. They are present to some degree in most adult faces at rest, and their depth increases with age regardless of how much or genuinely a person smiles. Observers in age estimation studies consistently identify nasolabial depth as one of the top predictors of estimated age.

The distinction matters for how you interpret your own face. If your concern is the lines that appear around your eyes when you smile, that is almost certainly a positive feature. If your concern is the depth of the crease from nose to mouth corner that is visible at rest, that is the age-associated type.

At 25, smile lines are almost entirely dynamic — they appear when the face moves and disappear when it relaxes. The skin is elastic enough to return to smooth after each expression. The nasolabial fold at rest is shallow; crow's feet appear only at peak smile intensity.

By 45, skin elasticity has reduced significantly through collagen loss (approximately 1% per year from the mid-20s). Dynamic lines begin to leave permanent marks — they are visible at rest even when the face is not actively expressing. This transition from dynamic to static lines is what most people mean when they say smile lines are making them look older.

The transition is heavily influenced by sun exposure (UV radiation accelerates collagen degradation), sleep quality, smoking, and genetic collagen density. Two people with identical smiling habits can have dramatically different nasolabial depth at 45 based primarily on these factors.

The Smile Tracker AI measures expression components rather than skin texture — it scores mouth curve, cheek lift, eye squint, and jaw openness from facial landmark positions rather than pixel-level analysis. This means smile lines do not directly lower your smile score.

What crow's feet do indicate — and what the AI detects indirectly — is orbicularis oculi activation. A smile that produces visible crow's feet is, by definition, one where the eye muscle is contracting. This is the same signal the AI uses for the eye squint component. So people with established crow's feet lines often score well on the Duchenne marker precisely because their eyes have learned the movement pattern that produces the lines.

For age estimation, the Guess My Age tool is sensitive to skin quality signals that are visible in the periorbital area — including the resting depth of periorbital lines. But this is about overall apparent age, not smile quality.