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.
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. “Everyone has melanin in the iris of their eye, and the amount that they have determines their eye color,” said Gary Heiting, a licensed optometrist and senior editor of the eye care website All About Vision, told CNN.
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.”