True fact: about 10,000 years ago, every human on Earth had brown eyes.
Now, half of all people in the U.S. have brown eyes. Worldwide, that number could be even greater.
The brown color comes from melanin, a pigment in our eyes that also gives a brown color to hair, skin and other cells.
The colored part of the eye is called the iris.
The iris is made up of two layers of muscle and other kinds of cells. In most people, the back layer has at least some brown pigment in it, even if their eyes don't look brown. In people with brown eyes, the iris’s front layer also has some brown pigment in its cells. The more melanin there is in the iris, the darker brown it will be.
Other Eye Colors
How did blue and other lighter-colored eyescome into the picture?
Scientists trace the historic change back to a single common ancestor. That person had a change in a gene that controls melanin production. This change, or mutation, is believed to have reduced the production of melanin in the iris.
Some eyes appear blue, green or hazel not because they have different color pigments, but because they have less melanin. With less melanin in the eye, less light is absorbed. That means more light is scattered out from the iris. When light is scattered, it reflects differently along the light color spectrum. So eyes with the least melanin in them will appear blue. If the iris has a little more melanin, then it will appear green or hazel.
Brown Eyes Aren’t Inherited from A Single Gene
Scientists used to think that a single gene determined your eye color. More current research suggests that as many as 16 different genes could be responsible for eye color. This helps explain why two parents with the same eye color can have children with an entirely different eye color.
A Baby’s Eye Color May Change to Brown
When babies are born, their eyes may sometimes appear blue while their melanin is still developing. Within about 12 months, cells will begin to produce melanin, and as more melanin builds up in the iris, eye color may darken.
Brown Eyes Are More Common in Certain Places
High levels of melanin in the eyes, hair and skin help protect people from the sun’s damaging rays. That explains why brown eyes occur more frequently in the hotter climates of Africa and Asia than in Europe. In Iceland, brown eyes are in the minority. As people move to less sunny locations, their need for protective pigment decreases. Eye color may have evolved as our early ancestors moved toward cooler parts of the world.
Connection Between Eye Color and Eye Health
People with brown eyes have a lower incidence of eye cancer, macular degeneration and diabetic retinopathy. Ophthalmologists are not exactly sure why, but believe that melanin pigment may give brown eyes more protection. On the flip side, a study found that people with brown eyes were just about twice as likely to develop cataracts than individuals with light eyes. The researchers did not look at why this is true, but they did rule out other things that could make cataracts more likely, like smoking and eye injury.
FAQs
This is because excess melanin (which causes the brown colors of the iris) protects the eyes from sunlight. Since warmer climates tend to have more sunlight, this means that brown eyes are more common in cultures near the equator. On the other hand, blue, green, and hazel eyes happen when the iris has less melanin.
Why brown is the most common eye color? ›
This is because excess melanin (which causes the brown colors of the iris) protects the eyes from sunlight. Since warmer climates tend to have more sunlight, this means that brown eyes are more common in cultures near the equator. On the other hand, blue, green, and hazel eyes happen when the iris has less melanin.
What is special about brown eyes? ›
Brown eyes are resilient.
Brown eyes are more resistant to problems because they have more melanin. It also helps to repair DNA damage and to keep the eyes moist. People with brown eyes are also less likely to develop certain types of eye diseases, such as age-related macular degeneration.
Why are brown eyes the most dominant? ›
The bey2 gene has one allele for brown eyes and one for blue eyes. The allele for brown eyes is the most dominant allele and is always dominant over the other two alleles and the allele for green eyes is always dominant over the allele for blue eyes, which is always recessive.
What is the rarest eye color? ›
While the global data on eye colors is limited, red and violet eyes are likely the rarest eye colors since they only affect a small group of people with albinism. But if you exclude eye colors brought on by albinism, then green and gray are likely the rarest.
What is the healthiest eye color? ›
Brown Eyes Are Associated With Few if Any Health Risks
“In general, everyone should make sure to wear 100 percent UV-blocking sunglasses when outdoors to minimize their chances of developing cataracts and other eye diseases,” Abugo advises.
What is the prettiest eye color? ›
One thing these survey results have in common is that light-colored eyes — green, gray, blue, and hazel — are named as the most attractive eye colors in the world. In one large survey of more than 66,000 people, green was chosen as the most attractive eye color.
Why are brown eyes so attractive? ›
These researchers posit that the rounder and softer features of brown-eyed individuals make their faces appear more babylike and, thus, more innocent or trustworthy. Tangentially, the researchers suggest that the sometimes longer and more angular features of people with blue eyes strip them of this quality.
Do brown eyes have more protection from the sun? ›
Eye Color Matters
Lighter-colored eyes have less pigment to protect against sun damage and UV radiation compared to darker-colored eyes. This means that people with green, hazel, or blue eyes are more sensitive to light and more susceptible to UV damage.
Why do brown eyes glow in the sun? ›
Sun exposure can cause the eyes to appear more or less intense by influencing the pigment cells in the iris. This means that brown eyes can temporarily darken or shift their color towards hazel or green due to increased melanin production when exposed to sunlight.
The brown color comes from melanin, a pigment in our eyes that also gives a brown color to hair, skin and other cells. The colored part of the eye is called the iris. The iris is made up of two layers of muscle and other kinds of cells.
What is the personality of someone with brown eyes? ›
If you have light or even medium brown eyes then you are a fun loving, caring and easy-going soul. You are a polite person and very independent indeed who loves making new friends. You are a very grounded person and do not care about worldly possessions. You will go out of your way to help those in need.
What does "brown eye" mean in slang? ›
show ▼±vulgar, slang for the anus.
What is the rarest hair and eye color combination? ›
According to an article by evolutionary biology professor Mark Elgar, PhD, of the University of Melbourne, blue-eyed redheads are the absolute rarest, with 0.17% of the population having that combination of hair and eye color. So if that describes you, you're most likely one in a million—or more!
Do purple eyes exist? ›
Red and violet
Although the deep blue eyes of some people such as Elizabeth Taylor can appear purple or violet at certain times, "true" violet-colored eyes occur only due to albinism. Eyes that appear red or violet under certain conditions due to albinism are less than 1 percent of the world's population.
What color eyes do most Irish have? ›
Where in the world are the most green eyes? The highest concentration of people with green eyes is found in Ireland, Scotland, and northern Europe. In fact, in Ireland and Scotland, more than three-fourths of the population has blue or green eyes – 86 percent!
Are true brown eyes rare? ›
Brown eyes are the most common eye color worldwide, with more than half of the global population having brown eyes.
