13 Fascinating Scientific Facts About Blue Eyes
Our eyes are arguably the most distinctive features of our faces, making us who we are.
The color of your hair is usually the same throughout your life. Although, it can appear to change depending on the light source, the actual pigment shouldn't shift (if your eyes do appear to change color, consult a specialist).
But your eyes aren't just a part of what makes your face look good. They can actually tell us a lot about your personality, your health, and even where you fit into the big story of human history. We talked to three experts - including doctors and researchers who specialize in eyes and human health - to learn more about blue eyes. We're about to uncover what's behind those sapphire peepers and some pretty cool - and weird - facts about your body.
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What determines eye color?
The color of your eye is decided mainly by how several genes combine, with the OCA2 gene playing the biggest part. The HERC2 gene also has a big influence on determining eye color.
These genes work together to regulate the pigment called melanin. "It's the pigment that determines the color of the eyes," says Jay Chhablani, MD, professor of ophthalmology at the University of Pittsburgh. "Higher levels of melanin cause darker pupils, while lower levels result in lighter or blue eyes."
in humans.
Are all people with blue eyes related?
The mutation affects the OCA2 gene, which controls the production of melanin. This mutation leads to a reduction in the amount of melanin.
Prior to the emergence of the mutation, it is stated that all humans had brown eyes, which is the natural color of melanin.
Facts about blue eyes
Three experts share their findings on what's unique about blue eyes. We discovered some fascinating facts that shed light on this exceptionally special trait.
There exists an eye color other than blue that is even less common.
To be exact, blue eyes are the second most common in the US, following brown eyes. Statistics from the American Academy of Ophthalmology reveal that approximately 27% of Americans have blue eyes, compared to 45% who have brown eyes. However, globally, a slightly smaller portion of individuals, between 8% to 10%, have blue eyes. Brown eyes still hold the top spot worldwide, with approximately 70% to 80% of the population sharing this characteristic.
People are often found with blue or brown eyes, but there is a very small number of people who have eyes of other colors. These might be referred to as green and gray. A smaller fraction of people even have eyes of different colors, a condition known as heterochromia.
There's a link between having blue eyes and a higher risk of melanoma.
People with light-colored skin and blue eyes have a reduced amount of melanin, which helps protect against ultraviolet light, says Gregory Papadeas, a dermatologist in Denver and a past president of the Colorado Dermatologic Society.
People with blue eyes are at a higher risk of contracting uveal melanoma, a relatively rare form of eye cancer that strikes roughly five out of every million individuals.
The color of your eyes, classified as blue, isn't actually the color blue. When we refer to the color blue, we're typically talking about the visible spectrum of light with a wavelength between approximately 450-495 nanometers. Your eyes, however, contain small structures called melanin and collagen. These structures scatter shorter wavelengths of light more than longer wavelengths, giving the appearance of blue eyes.
The color of your iris isn't actually the result of the pigment itself. Instead, it's how much melanin you have and how it scatters light.
Light-sensitive areas with less melanin, like blue eyes, do not absorb as much light. Any light that manages to enter the pupil is dispersed by fibers of collagen, giving the eyes a blue appearance. (Collagen fibers are what keeps the eye's structure stable.)
On the other hand, people with more melanin and darker eyes absorb more light.
People with blue eyes may experience less pain.
Women in labor were grouped by eye color. Those with brown or hazel eyes experienced more anxiety, difficulty sleeping, and increased pain compared to women with lighter eye colors. It's worth noting that how we perceive pain can also be influenced by other factors, including age, sex, and hair color.
Research suggests that people with blue eyes may be more competitive.
Looking to challenge yourself in your next sports or academic pursuit? Find a rival with striking blue eyes.
People who have light-colored eyes, including those with blue eyes, tend to be seen as being more self-centered and doubtful. On the other hand, individuals with darker eyes are viewed as more empathetic and concerned about others.
Men with blue eyes may have female features in their faces.
They have a more prominent lower jaw and lips, a larger nose and brow, and closer-set eyes.
Some of this might be explained by the fact that non-brown eye colors appear to develop more easily if the body's tissues have a higher amount of estrogen during fetal development, says Frost. “If a male fetus has more estrogen than average, it is more likely to develop blue eyes and a more feminine face,” he explains. “This association is missing in women because a female fetus normally has enough estrogen in its body tissues to feminize the face.”
People with blue eyes have a greater likelihood of developing macular degeneration.
It may seem unusual, but the color of your eyes has a potential link to certain eye disorders. Research has found a connection between blue eyes and an increased risk of macular degeneration. Specifically, the macula is the part of the retina in the center of your eye that converts light into electrical signals sent to the brain for processing. When the cells in the central part of the retina are damaged, it can cause a loss of central vision.
"There's a fairly well-established connection between macular degeneration and blue eyes," Dr. Chhablani notes. He believes this is mainly because blue eyes allow more light to enter the eye, which can, in turn, harm the eye.
Research has demonstrated that having blue eyes is correlated with a reduced likelihood of developing cataracts.
A study of 3,654 Australians with dark- and light-colored eyes discovered a significantly greater risk of cataracts in individuals with dark eyes.
The biggest risk factor for cataracts, however, is aging. The National Eye Institute states that more than half of Americans over the age of 80 have had or are currently dealing with cataracts.
People with blue eyes are less likely to have vitiligo.
One more benefit - having blue eyes may also mean that you have a lower chance of developing vitiligo, which is a condition where patches of skin lighten up. Scientists think that the genes responsible for blue eyes and vitiligo might be related.
People with blue eyes are more prone to being sensitive to light.
The term for this phenomenon is "photophobia," and indeed, individuals with blue, green or gray eyes do appear to be more sensitive to both sun exposure and fluorescent lighting. Once again, the extent of pigmentation in one's eyes is the determining factor. The less melanin present, the more vulnerable the eyes become to harsh light.
When we're outdoors, especially during the middle of the day.
White-eyed people might consume more alcohol.
Research found that people with blue eyes have an 83% higher likelihood of developing alcohol dependence compared to those with brown eyes. Further genetic studies revealed significant connections between genes that control eye color and those that influence alcohol dependency.
About the experts
- He is a doctor of medicine, a professor of ophthalmology, and a vitreoretinal surgeon at the Department of Ophthalmology at the University of Pittsburgh. In addition, he has published over 580 articles in respected scientific journals and is also the editor of three books that deal with problems of the eyes.
- Dr. , is a private dermatologist in Denver. He is a distinguished fellow of the American Academy of Dermatology and has served as the past president of both the Colorado Dermatologic Society and the American Osteopathic College of Dermatology.
- He earned a PhD in anthropology from Université Laval in 1995. His chief area of focus has been the impact of sexual selection on noticeable human characteristics, particularly skin tone, hair color, and eye color. Although he has semi-retired, he continues to work part-time as a translator and copy editor for an anthropology academic journal and for researchers studying northern indigenous peoples.
Sources:
- The blue eye color in humans may be due to a single original genetic mutation that occurred in a regulatory area within the HERC2 gene, which stops the expression of the OCA2 gene.
- “Genetic markers for skin tone are new risk factors for eye melanoma”
- The Relationship Between Iris Color and the Risk of Developing Uveal Melanoma
- “Understanding Uveal Melanoma: Demographics, Causes, and Treatment Options for the Original Disease”
- Relationship between eye color and types of pain experienced in healthy women
- Eye color is linked to Disagreeableness in Northerners: Supporting evidence for Frost's theory
- Men's eye color is associated with certain personality traits or perceived personality characteristics, but it does not directly cause dominant behavior.
- Retinal Vascular Diameter, Iris Color, and Age-Related Macular Degeneration in the Irish Nun Eye Study
- Color of the iris, ethnic background, and progression of age-related macular degeneration
- “Blue Mountains Eye Study on Iris Color and Cataracts”
- Eye Color: A Potential Indicator of Alcohol Dependence Risk in European Americans
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