Buzz
Eyebrows function like a multi-tool on the human face. Experts believe they persisted, even after evolution led to humans losing most of their body hair, because they offer a range of important functions.
First, they protect your eyes. The brow ridge’s shape, along with the outward-growing hairs of the eyebrows, directs sweat, rain, and moisture away from your eyes, keeping your vision unobstructed. They can also capture dust or shield your eyes from sunlight.
Second, they play a crucial role in nonverbal communication. Researchers studying facial expressions assert that eyebrows are key to conveying emotions like happiness, surprise, and anger, a feature that may have also been used by our human ancestors.
In 2018, scientists attempted to decode why the brow ridges of Homo neanderthal and Homo erectus were far more pronounced than ours. They initially suggested that it could be related to supporting their bite force. However, after adjusting a 3D model of an ancient hominin, they found that bite pressure alone didn’t explain the prominent brows. The researchers then proposed that social communication was likely the driving factor instead.
Over thousands of years, our eyebrows have evolved to become smaller, more flexible, and essential for nonverbal expression. For instance, modern sign language speakers use eyebrow movements to enhance the meaning of their hand gestures.
Third, eyebrows serve as an identification feature. They contrast with the forehead, are easily visible from a distance, and don’t change much over time, making them ideal for recognizing individuals. In a 2003 MIT study [PDF], participants were shown a photo of Richard Nixon with his eyes digitally removed, and another image where his eyebrows were erased. The participants found it significantly harder to identify Nixon and other public figures when their eyebrows were missing.
The lesson here? If you want to go incognito, ditch the sunglasses and shave off your eyebrows.
