Similar to many human characteristics, blue eyes are influenced by genetics, and each person has their own distinct shade. The way this functions is quite akin to individuation.
fingerprints
, making our eyes one of the most distinctive features of us.
The hue of your eyes actually stems from the iris, which is the colored circle encircling the dark pupil at the center of your eye. This characteristic differs from several other features one might confuse for eye coloring.
inherited traits
Like the hue of your hair, eye color usually remains constant over your lifetime. Of course, it might look different based on lighting conditions, but the pigmentation should stay stable (should you notice changes in your eye color, consult an expert).
However, your eyes serve more than just an attractive aspect of your facial appearance. They offer unexpected insights into your character, state of well-being, and origins within the grand narrative of human history. We consulted three specialists—medical professionals and investigators who possess extensive knowledge regarding ocular biology and overall human wellness—to uncover comprehensive information about blue eyes. This includes exploring whether individuals with blue eyes share common ancestry as well as learning some bizarre truths concerning the intricacies of the human physique. Continue perusing for every detail you might desire to discover about those striking azure irises.
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What determines eye color?
Your eye color is primarily influenced by the interplay of multiple genes, with the OCA2 gene being particularly significant. Another key player in this process is the HERC2 gene.
All these genes work together to control the production of melanin, which determines eye color according to Jay Chhablani, MD, an ophthalmology professor at the University of Pittsburgh. He explains that increased amounts of melanin result in darker pupils, whereas decreased levels cause lighter or bluish-colored eyes.
Certainly, not every pair of blue eyes looks identical. These differences arise from varying amounts of melanin present too. This pigment plays a role in setting the hue of your hair and skin as well. Higher melanin content typically leads to darker tones in these features. So, should your genetic makeup bless you with both azure irises and fiery locks? You’d be showcasing quite a striking combination.
least common hair color and iris hue pairing
in humans.
Do all individuals with blue eyes share a common ancestry?
Indeed, all individuals with blue eyes share a common progenitor. By examining the DNA of blue-eyed persons from regions such as Jordan, Denmark, and Turkey, scientists were able to track down this characteristic to a solitary genetic alteration within an ancient person that emerged sometime between 6,000 and 10,000 years past. The research team detailed these insights in a paper featured in a scientific journal.
Human Genetics
The mutation occurs in the OCA2 gene, responsible for regulating melanin production. This specific alteration reduces the quantity of melanin produced.
Prior to the emergence of the mutation, the authors indicate that all humans had brown eyes, which is the default hue determined by melanin.
Facts about blue eyes
Sharing a common ancestor is merely one intriguing aspect of having blue eyes. To learn more about what makes blue-eyed individuals exceptional, we consulted with three specialists.
The rarity of blue eyes does not make them the least common eye color.
Actually, it ranks as the second most prevalent eye color in the United States following brown eyes. The American Academy of Ophthalmology reports that approximately 27% of Americans possess blue eyes, whereas around 45% have brown eyes. Globally, between 8% to 10% of people have blue eyes, maintaining its position as the runner-up behind brown eyes, which are found in 70% to 80% of the global population.
The
rarest eye colors
are green and gray. An even smaller proportion of people have different-colored eyes, which is called heterochromia.
People with blue eyes have an increased likelihood of developing melanoma.
Individuals with fair skin and light-colored hair are at an increased risk of developing melanoma; however, people with blue eyes also face this heightened risk. Actually, possessing light-colored eyes can be a risk factor irrespective of one’s hair color.
red hair
And/or having fair skin, notes Gregory Papadeas, DO, a dermatologist from Denver and former president of the Colorado Dermatologic Society. This is due to the fact that individuals with blue eyes possess lower levels of melanin, which typically provides protection against ultraviolet light, as he points out.
People with blue eyes also face a greater likelihood of developing uveal (eye) melanoma, a uncommon cancer that impacts approximately five out of every million persons.
The color of your blue eyes isn’t really blue.
The hue of your iris isn’t determined by the pigment color itself. Rather, it’s due to the quantity of melanin present and the way this melanin interacts with light.
Blue eyes (along with other lighter shades signaling lower levels of melanin) take in less light. The light that enters via your pupil gets dispersed by the collagen fibers, giving the eyes their blue appearance. These collagen fibers also play a role in maintaining the eye’s structural integrity.
In contrast, individuals with higher levels of melanin and darker eyes tend to absorb greater amounts of light.
People with blue eyes might experience less discomfort.
One benefit of those sky-blue peepers is research suggesting individuals with light-colored irises (such as blue or green) exhibit greater pain tolerance compared to their dark-eyed counterparts. This was highlighted in a preliminary study featured in the
Journal of Pain
During childbirth, women were classified based on their eye color. Individuals with brown or hazel eyes experienced higher levels of anxiety, faced greater difficulties sleeping, and reported more pain compared to those with lighter-colored eyes. It’s important to note that our perception of pain is influenced by various factors including age, gender, and even hair color.
People with blue eyes might be more competitive.
Seeking a push in your most recent physical or mental pursuit? Challenge a friend who has blue eyes to compete with you.
Scientists examining the potential link between eye color and specific personality traits discovered that individuals of Northern European ancestry with light-colored irises exhibited lower levels of agreeableness, essentially indicating they tend to be more competitive. This research, published in the journal, revealed these findings.
Current Psychology
, highlighted light-eyed people, such as those with blue eyes, as being more self-centered and doubtful. In comparison, individuals with darker eyes are perceived as more empathetic and generous.
Males with blue eyes might have facial features resembling those of females.
Studies indicate that symptoms similar to “baby blues” often correlate with characteristics commonly found in feminine faces, including small and pointed chins, thin lips, petite noses, and widely spaced eyes. According to Peter Frost, Ph.D., an anthropologist focusing on how sexual selection influences observable human attributes, brown eyes tend to be connected with more masculine appearances.
facial features
, including wider chins and mouths, bigger noses and eyebrows, and more closely spaced eyes.
Part of this can be attributed to the idea that non-brown eye colors tend to manifest more readily when body tissues experience a elevated levels of estrogen during fetal development, as stated by Frost. He elaborates, “Should a male fetus possess above-average estrogen levels, it becomes more probable for him to develop blue eyes along with facial features that appear more feminine.” This connection does not hold true for females since their typical estrogen presence in bodily tissues usually leads to feminization of the face naturally.
People with blue eyes have an increased likelihood of developing macular degeneration.
It might sound odd, but your eye color could increase your likelihood of developing specific eye conditions. Various research efforts have highlighted a connection between blue eyes and a higher susceptibility to macular degeneration. This condition affects the macula—the key area within the retina responsible for transforming visual information into electrical impulses sent to the brain. Damage to these cells in the macula leads to a gradual loss of central vision.
“Research has firmly linked age-related macular degeneration with having blue eyes,” states Dr. Chhablani. This connection likely exists because blue-eyed individuals have less pigmentation in their irises, allowing greater penetration of light into the eye, which may cause retinal harm over time, as he clarifies.
People with blue eyes experience fewer cataracts.
On the positive side, individuals with blue eyes might have a reduced chance of developing cataracts, according to Dr. Chhablani. Cataracts occur when the lens of your eye, located directly behind the iris, turns hazy and impairs sight.
American Journal of Ophthalmology
A study involving 3,654 Australians with both dark and light colored irises revealed a significantly greater chance of developing cataracts among those with darker eyes.
The highest risk factor for cataracts is age. According to the National Eye Institute, over fifty percent of Americans who are 80 years old and older either currently have cataracts or have had them in the past.
People with blue eyes are less prone to developing vitiligo.
A further advantage? People with blue eyes might have a reduced chance of developing vitiligo, a condition characterized by areas of skin losing pigment. Experts suggest that the genes responsible for blue eyes could potentially be linked to those associated with vitiligo.
People with blue eyes are more sensitive to sunlight.
The medical term for this condition is “photophobia,” and indeed individuals with blue, green, or grey eyes tend to exhibit greater sensitivity not only to direct sunlight but also to artificial lighting like fluorescents. This can largely be attributed to the level of pigment present in one’s eyes; lesser amounts mean reduced protection from intense illumination.
That being said, it’s advisable for everyone, irrespective of their skin, hair, or eye hue, to avoid direct sunlight and to
protect our eyes
When we’re outdoors, particularly around midday.
People with blue eyes might consume greater amounts of alcohol.
Research indicates that individuals with blue eyes might consume greater amounts of alcohol and could also have a higher likelihood of developing alcohol dependence. A study featured in the
AJMG – American Journal of Medical Genetics
Participants with blue eyes exhibited an 83% increased likelihood of facing alcohol dependency when contrasted with individuals having brown eyes. Further genetic examination revealed several interconnections between the genes responsible for eye color and those associated with alcohol dependence.
About the experts
-
Jay Chhablani
, MD, serves as a professor of ophthalmology and specializes as a vitreoretinal surgeon within the Department of Ophthalmology at the University of Pittsburgh. With over 580 publications in esteemed academic journals, he also holds the role of editor for three books focused on ocular diseases. -
Gregory Papadeas
, DO, is a dermatologist who practices privately in Denver. He holds fellowship status with the American Academy of Dermatology and has previously served as the president of both the Colorado Dermatologic Society and the American Osteopathic College of Dermatology. -
Peter Frost
In 1995, he earned his doctoral degree in anthropology from Université Laval. His primary area of study focuses on how sexual selection influences observable human characteristics such as skin pigmentation, hair hue, and ocular coloration. Although he is mostly retired, he continues to serve as both a translator and copy editor for an anthropological publication and assists scholars conducting research among indigenous populations in the north.
Sources:
-
Human Genetics
Human blue eyes could result from a precise founding mutation in a regulatory segment of the HERC2 gene that stops the OCA2 gene from expressing. -
Scientific Reports
:
Novel genetic markers linked to pigmentation serve as risk factors for uveal melanoma. -
Journal of International Molecular Sciences
Iris Color as an Indicator for the Development of Uveal Melanoma -
Clinical Ophthalmology
Uveal Melanoma: Epidemiology, Etiology, and Treatment of Primary Disease -
The Journal of Pain
Relationship between iris hue and pain responses in females without medical conditions -
Current Psychology
Eye color indicates Disagreeableness among North Europeans: Evidence Supporting Frost’s Theory -
Personality and Individual Differences
Eye color indicates but doesn’t directly affect how dominant men are perceived. -
Investigative Ophthalmology and Vision Science
Retinal Blood Vessel Width, Iris Pigmentation, and Age-Linked Macular Degeneration in the Irish Sister Ophthalmology Research -
Clinical and Experimental Ophthalmology
:
“Color of iris, ethnic background, and development of age-related macular degeneration” -
American Journal of Ophthalmology
:
Iridal hue and cataracts: findings from the Blue Mountains Eye Study -
AJMG – American Journal of Medical Genetics
Eye Color: A Possible Marker for Alcohol Dependence Risk Among European Americans
