Blue eyes have been the subject of many poems, lyrics, and gushing diary entries, but brown-eyed beauties can have a moment of smugness. As it turns out, on a physical level, there’s no such thing as blue-colored eyes. They’re actually all brown.
The difference between brown eyes and blue eyes
Melanin, the pigment that gives all irises (not to mention your skin and hair) is naturally brown, no matter what your eye color. So how does a dark brown pigment show up bright blue? It all comes down to how much melanin you’ve got. “We all have melanin granules that give our skin pigmentation and determine the color of our skin, and the same is true for the eyes,” explains Benjamin Bert, MD, an ophthalmologist at MemorialCare Orange Coast Medical Center in Fountain Valley, CA. “So even though the eye appears blue or brown, both have melanin at the base of the color.” Put simply, a blue eye has a lot less melanin in the iris than a brown eye.
From there, it’s basically just a light trick. The more melanin you have, the more light your eyes can absorb. With a lot of pigment absorbing that light, your eyes will look brown.
On the other hand, blue eyes have the least amount of pigment, meaning they’ll also absorb the least light. Instead, more light is reflected back out in the form of blue wavelengths. (That light reflection also explains why some people’s eyes seem to change color—it depends on the type of light entering their eyes.) The melanin levels in people with green and hazel eyes falls somewhere between blue- and brown-eyed folks.
Still, there’s no need to start lamenting the lie behind your “true blue” eyes. After all, the sky isn’t technically blue either (it gets its color because the short blue waves from the sun’s white light scatter more than the long red ones), but that doesn’t mean you should correct anyone commenting on a cloudless blue sky. Just take a moment to appreciate your peepers’ gorgeous shade as you see it—and maybe crank up “Brown Eyed Girl.”