Table of ContentsView AllTable of ContentsWhy Your Eyes Are the Color They AreEye Color PercentagesGenetics of Eye ColorBrown EyesOther Eye ColorsEye Color at BirthEffect on Eye HealthFrequently Asked Questions
Table of ContentsView All
View All
Table of Contents
Why Your Eyes Are the Color They Are
Eye Color Percentages
Genetics of Eye Color
Brown Eyes
Other Eye Colors
Eye Color at Birth
Effect on Eye Health
Frequently Asked Questions
More than half of the world’s population has brown eyes, making it the most common eye color overall. However, brown is not always the most common when it comes to particular ethnic groups.
Eye color comes from pigmentation in theiris—a muscular tissue that controls thesize of your pupiland allows light inside your eye. Inside the iris is a variety of pigments that gives your eyes their color. The combination of pigments and how they are distributed determine your specific hue. All of this comes down to genetics.
This article explains why brown is the most common eye color and how certain eye colors are more common in different groups of people. It also discusses the biological and genetic factors behind eye color.
Leland Bobbe / Getty Images
Melanin, a yellow-brown pigment also responsible for skin tone, is the most predominant one. Even people with blue or green eyes have some melanin in their eyes. People with brown eyes have melanin in both layers of the iris, whereas people with lighter-colored eyes have melanin in the back layer only.
The pigment pheomelanin provides the color for green and hazel eyes. A red-orange pigment, pheomelanin is also responsible for auburn hair. This pigment is most commonly found in people with European ancestry, most notably in Ireland and Scotland.
The darkest pigment is eumelanin, a black-brown hue abundant in dark eyes. The concentration of eumelanin determines the intensity of the eye color. Also responsible for black hair, eumelanin is most abundant in people with African, Asian, Central American, and South American ancestry.
Brown is the most common eye color in both the United States and the world.More than half of all people have brown eyes. Green eyes are considered to be the rarest—only 2% of all people have them.
Here’s a breakdown of the percentages of people in the United States who have each of the various eye colors:
Unusual Eye Colors
Though rare, people can have red or pink eyes or even two different colored eyes.
People who have albinism may not have any pigment in their eyes, so their eye color may be red or pink. This happens because the iris is clear without melanin, allowing blood vessels to show through.
Heterochromia, having two different eye colors, is very rare. Aniridia is a rare condition in which a person is missing part of the iris in one or both eyes.
Genes that are involved in determining your eye color include:
Why Brown Is Most Common
Researchers believe that brown eyes are the most common because our first human ancestors had this eye color. High levels of melanin help to protect the eyes from damaging sun rays.
Brown eyes are more common in people whose ancestors came from hot, sunny climates such as Africa, Asia, and South America. This helped to guard their vision against ultraviolet rays and helped them focus in bright light.
Reasons for Other Eye Colors
Blue and other eye colors developed from a mutation (genetic change). A single ancestor probably had a mutation 6,000 to 10,000 years ago that affected melanin production and resulted in lighter-colored eyes.
Researchers believe that lighter eyes appeared once Early Man left Africa and spread to Europe. These areas had less sunlight, which meant there was less need for melanin.
The reason why someone’s eyes look blue has to do with the amount of melanin in the iris. When there is less pigment, there is less light that can be absorbed. The light is scattered and reflects the sky. Eyes that have the smallest amount of melanin are blue.
Other pigments are also at play. Green eyes, for example, have more pheomelanin than melanin. Black eyes have more eumelanin.
Why Eyes Change Color
Many babies are born with blue eyes, but they change color over time. The melanin and other pigments increase in their eyes, changing them and making them darker or lighter within 12 months. The buildup of pigment takes time to develop in babies.
Eye color doe not typically change after that. If it does, it can indicate a problem. An adult’s eyes can change color because of:
If your eye color changes color in adulthood, see an ophthalmologist or other healthcare provider.
People with certain eye colors are more likely to experience different health conditions.
There are advantages to having brown eyes, such as a lower risk of:
If you are concerned about your eye color or the overall health of your eyes, talk to your eye doctor and get an eye exam.
Frequently Asked QuestionsGreen has traditionally been considered the rarest eye color, but grey or violet eyes are even rarer.Learn MoreWhat Is the Rarest Eye Color?Yes. When you experience strong emotions, the body releases different brain chemicals that can constrict or dilate the pupil. This can cause a shift in how eye pigments are dispersed, which can make your eyes look as if they changed color.Blue eyes are commonly more sensitive to light because they do not have as much melanin to block out UV rays. The lighter the hue of an eye, the more sensitive to light it is. Pale blue or light grey eyes are more sensitive to light than dark blue eyes.
Green has traditionally been considered the rarest eye color, but grey or violet eyes are even rarer.Learn MoreWhat Is the Rarest Eye Color?
Green has traditionally been considered the rarest eye color, but grey or violet eyes are even rarer.
Learn MoreWhat Is the Rarest Eye Color?
Yes. When you experience strong emotions, the body releases different brain chemicals that can constrict or dilate the pupil. This can cause a shift in how eye pigments are dispersed, which can make your eyes look as if they changed color.
Blue eyes are commonly more sensitive to light because they do not have as much melanin to block out UV rays. The lighter the hue of an eye, the more sensitive to light it is. Pale blue or light grey eyes are more sensitive to light than dark blue eyes.
7 Sources
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read oureditorial processto learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
American Academy of Ophthalmology.Why are brown eyes most common?
Wollstein A, Walsh S, Liu F, et al.Novel quantitative pigmentation phenotyping enhances genetic association, epistasis, and prediction of human eye colour.Sci Rep.2017;7:43359. doi:10.1038/srep43359
American Academy of Ophthalmology.Eye color: Unique as a fingerprint.
American Academy of Ophthalmology.Your blue eyes aren’t really blue.
American Academy of Ophthalmology.Why are my eyes changing color?
Grigore M, Avram A.Iris colour classification scales—then and now.Rom J Ophthalmol. 2015;59(1):29-33
Meet Our Medical Expert Board
Share Feedback
Was this page helpful?Thanks for your feedback!What is your feedback?OtherHelpfulReport an ErrorSubmit
Was this page helpful?
Thanks for your feedback!
What is your feedback?OtherHelpfulReport an ErrorSubmit
What is your feedback?
