Where Do Blue Eyes Come From?

Researchers believe there is one ancestor responsible for this eye color

Your genes determine whether you have blue eyes. If you inherit blue-eye genes from your parents, it means that your eyes will have less of a pigment called melanin in them. Approximately 27% of people in the United States and between 8% and 10% of the world's population have blue eyes.

This article discusses where blue eyes come from and how having blue eyes may increase your risk for certain health conditions.

Close up of fair skin woman with blue eyes

PhotoAlto / Milena Boniek / Getty Images

Why Some Eyes Are Blue

The iris is the colored part of your eye that has multiple layers. For just about everyone, the back layer of each eye is brown. The top layer, called the epithelium, is where the melanin (pigment) that gives an eye its color lives. For blue-eyed people, this top layer lacks melanin.

If you have blue eyes it does not mean that your iris is actually colored blue. Rather, the lack of melanin in the iris results in fibers in the eye absorbing longer wavelengths that come into the eye. Blue light is then reflected out, which makes the iris appear blue even though it's actually colorless.

Genetics of Blue Eyes

Both parents have to pass along the blue eye gene in order for their child to have blue eyes. That doesn't necessarily mean that the parents themselves have to have blue eyes; it's possible they carry the gene, but it is recessive. However, a blue-eyed child is almost certain if both parents have blue eyes.

Blue eyes actually didn't exist 10,000 years ago. Researchers believe there is one ancestor responsible for blue eyes that descended from the Black Sea region of southeastern Europe anywhere between 6,000 to 10,000 years ago.

This one person with a genetic mutation had children, and the trait was passed to the next generation. As that generation had children and moved around, the blue eye mutation continued to spread across many parts of the globe. 

This means everyone with blue eyes has one thing in common—they're all related. Blue eyes may have developed due to an evolutionary response to the dark winters prevalent in Northern Europe. In theory, blue eyes may have protected a person from acquiring vision disorders caused by these periods.

Why Do a Baby's Blue Eyes Sometimes Change?

It may take up to six months for the gene responsible for creating the pigment in the eyes to activate melanin production. A baby's eyes may be blue during this time, but later change color. If this gene activation never happens, a baby's eyes will stay blue.

Benefits of Blue Eyes

Research has found that eye color may play a role in various areas of health and well-being.

Cataracts

A cataract is a clouding of the eye's lens. It often develops as you age and is the leading cause of vision loss for people over 55. If you have a darker iris color, you are at a greater risk of developing this eye disease. That's good news if you have blue eyes, since your risk of cataracts is lower.

Seasonal Affective Disorder

While limited, there is some research showing that blue eyes may protect you against seasonal affective disorder. Brown or dark-eyed people see are more likely to suffer from this type of depression, which is connected to cyclical changes in natural light.

Attractiveness

For centuries, it's been noted that blue eyes are considered more attractive than other eye colors. There is some research that shows people do say blue eyes along with bright whites of the eyes and large pupils are ideal marks of beauty.

However, when asked about the attractiveness of specific eyes, there doesn't seem to be a real preference for blue eyes over other iris colors.

Risks of Blue Eyes

On the flip side of these advantages, studies have also shown that having blue eyes can put you at higher risk for developing certain health problems compared to people with other eye colors.

For example, researchers are looking at the connection between having blue eyes and:

Eye Cancer

Eye health providers remind almost everyone with blue eyes to wear sunglasses to reduce their risk of potential eye cancers like eye melanoma. In the same way, you can get melanoma on your skin, you can also get melanoma in your eye. 

Eye melanoma is known to be more common for those with fair skin and light-colored eyes. While ocular melanomas may happen at any age, the risk goes up as you get older.

Type 1 Diabetes

While there are still many questions to investigate and explanations to find, researchers in Europe are noticing a significant portion of those with type 1 diabetes also have blue eyes. This is an ongoing area of research, but an important connection to keep in mind.

Macular Degeneration

The macula, which is at the retina's center, is susceptible to damage as you age. This damage will cause your vision to become blurrier and more distorted—a condition called macular degeneration.

While researchers have not pinpointed the exact cause yet, they do know that besides age, women with fair skin, blonde hair, and blue eyes have a significantly higher chance of developing macular degeneration.

Hearing Loss

Scientists are looking into the possibility of those who have blue eyes being at higher risk for sensorineural hearing loss.

This form of hearing loss comes from damage to the inner ear or to the nerve going from the ear to the brain. Since the inner ear uses melanin, and blue eyes come from a lack of melanin, some researchers hypothesize there may be a link between eye color and acquired hearing loss.

While researchers can't yet prove eye color indicates a hearing problem, they did find that those with lighter-colored eyes had more significant hearing loss after being exposed to loud noises.

Summary

Blue eyes are an inherited trait. If you have blue eyes, it means the iris part of your eyes lacks melanin, so, technically, blue eyes don't have any color. They look blue because of how light is reflected.

Having blue eyes has its advantages. They lower your risk of developing cataracts, for instance. However, they might increase your risk of health problems like type 1 diabetes and eye cancer. Protecting your eyes and getting regular check ups is important no matter the color of your irises.

Frequently Asked Questions

  • How does a parent with a different eye color have a blue-eyed child?

    There are two main genes on chromosome 15 that determine a person's eye color: OCA2 and HERC2. Blue eye color is a recessive trait, but brown-eyed parents can still produce a blue-eyed child if both parents carry the genes for blue eyes.

  • Why do some people have light blue eyes and others have dark blue?

    Eye color is partially affected by light, especially blue eyes, which get their color specifically by light entering and reflecting out of the eye. This can make the blue eyes look slightly different depending on the type of lighting conditions.

  • How rare are blue eyes?

    Only about 8 % to 10% of the world's population has blue eyes. To put that in perspective, 79% of people have brown eyes.

  • Which country has the most people with blue eyes?

    Blue eyes are more concentrated in certain regions than others. Estonia is the country most known for its fair-skinned, blue-eyed population, followed closely by Finland. Ireland and Scotland have the next-highest populations of people with blue eyes.

10 Sources
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
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