The Real Reason We Have Eyelashes

Eyelashes are one of the finest features on the human face, easy to overlook unless they've been cosmetically enhanced. But despite their low-key existence, eyelashes actually serve an important purpose, one that extends beyond cosmetic beauty or using a loose eyelash to make a wish. The fine hairs around our eyes — loved for their aesthetic potential and hated when they land in the eyeball and cause pain and irritation — are actually part of the human body's external protection system.

You might know that the eyebrows serve a protective purpose. Dr. Stephanie Marioneaux, clinical spokesperson for the American Academy of Ophthalmology, told LiveScience that eyebrows redirect sweat, dandruff, and dirt to outside edges of the eye, if they don't trap these irritants altogether. This, and the eyebrows' impact on facial expressions, make their importance obvious. But few people realize that eyelashes are just as important to the safety of our eyes.

In the same LiveScience interview, Dr. Marioneaux also covered the importance of eyelashes. Like eyebrows, they protect our eyes. Sometimes this means filtering out potential irritants that our eyebrows don't, or protecting our eyes from things that come from directions the brows can't block.

Most of the time, however, the eyelashes protect our eyes through something called a blink reflex, according to Dr. Marioneaux. She equates eyelashes to a cat's whiskers. Both are fine hairs that react to touch by twitching and alerting the body that something is getting close to the face. In the case of eyelashes, this means that something is specifically getting too close to the eye. Without this reflex, explains Dr. Marioneaux, we would instead blink only when we see something coming toward our eye, or after something has already made contact.

This function makes eyelashes handy enough. But a 2019 study published by the Royal Society found another potential service eyelashes provide. According to the study, eyelashes can slow the evaporation rate of the liquid on our eyes, keeping them hydrated longer. The study is unique and has yet to be duplicated, but it lends another layer of utility to the often-ignored eyelash.