You may wonder what the rarest eye color is in humans. The color spectrum ranges from the relatively common brown to the exceedingly rare hues such as red or violet. But, there is no easy answer regarding which color is the most rare because genetics and geography play into how common a shade is. For example, brown is by far the most common eye color worldwide (79%), but blue is the most common color in the United Kingdom (48% blue, 30% green, 22% brown).
Ranking the Rarest Human Eye Color
To begin, let’s consider eye colors in order from the rarest to the most common:
- Black: Truly black eyes only result from a condition called aniridia, where the eye lacks an iris so only the dark pupil is visible. The cause of aniridia is a rare chromosome mutation that only occurs in one of 60,000-90,000 births.
- Red/Violet: Red and violet eyes mainly occur in albinos who lack melanin, the pigment responsible for skin, hair, and eye colors. In the absence of melanin, light scatters or refracts off the blood vessels in the eye, giving it a red or violet appearance. Violet is less common than red. Worldwide, albinism affects approximately one in 17,000 people. But, the prevalence is around 1 in 5,000 people in sub-Saharan Africa and 1 in 1,000 in parts of southern Africa.
- Purple: The presence of blood or blood vessels in the irises of a brown-eyed person sometimes produces purple irises.
- Green: Green is one of the rarest eye colors, found in less than 2% of the world’s population. It’s thought to be due to a combination of light amount of melanin and the Rayleigh scattering of light in the stroma.
- Amber: Amber eyes, a golden yellow color, are rare but more common than green. This eye color is the result of the presence of lipochrome, a yellow pigment.
- Gray: Gray eyes are a variant of blue eyes, where the iris lack melanin. While quite rare worldwide, the eye color is not particularly uncommon in people in Northern and Eastern Europe.
- Hazel: Hazel eyes are a mixture of green, gold, and brown hues. They are somewhat rare but more common than gray, amber, and green eyes.
- Blue: Around 8-10% of the world’s population has blue eyes, particularly in Northern European populations due to a high prevalence of the HERC2 gene that is associated with this eye color.
- Brown: Brown eyes are the most common, with over 55% of the world’s population sporting this color, largely because melanin is very common and the genes promoting brown coloration are dominant. Black eyes are actually very dark brown (with the exception of aniridia).
But, the most rare eye color varies depending on a population’s genetic heritage. Overall, the rarest eye color is a toss-up between red and purple (since true black does not involve an iris). Green, amber, and gray are uncommon in certain populations. Blue and brown eyes are not rare globally, but blue is uncommon in some locations.
Heterochromia is a fascinating condition where an individual’s eyes are two different colors. This can be complete (each eye a different color), partial (part of one eye is a different color), or central (spikes of different colors radiate from the pupil). This condition arises from genetics, injury, or certain diseases. It affects less than 1% of the population. So, it is less common than green or gray eyes, but not as rare as red or violet eyes.
How Eye Color Works
Eye color mainly depends on two factors: the pigmentation of the eye’s iris and the way the iris scatters light passing through it. The pigmentation depends on two main types of melanin: eumelanin (brown-black pigment) and pheomelanin (red-yellow pigment). Blue, gray, and red eyes lack these pigments. Other eye colors result from the interplay between the mixture of melanin and light scattering. The primary specific genes involved in eye color are OCA2 and HERC2, but there at least 10 genes that play a role.
Geography and genetics interplay significantly to influence the rarity of eye colors. For instance, blue eyes are common in Northern Europe but become progressively rarer as one moves south or east. Similarly, green eyes are prevalent in Iceland and parts of Europe. People across the globe have brown eyes, but they are prevalent in populations from Africa, East Asia, and Southeast Asia.
10 Facts About the Rarest Eye Color
For a quick trivia roundup, here are some interesting facts about human eye color:
- Eye color changes over time. The most significant changes occur in the first years of life due to melanin production and genetic influence.
- Blue-eyed individuals share a common ancestor with every other blue-eyed person in the world. This eye color originated between 6,000 to 10,000 years ago as a result of a genetic mutation.
- Hazel eyes exhibit color shifts from brown to green, depending on the lighting. Blue eyes and gray eyes also appear differently, depending on lighting and their surroundings.
- The Guinness World Record for the most changes in eye color goes to Elizabeth Taylor, whose violet eyes would appear blue, gray, or purple depending on the lighting and makeup.
- Some medications and diseases affect eye color. For example, Horner’s syndrome leads to a lighter-colored iris, while pigmentary glaucoma leads to a darker iris.
- Although rare in humans, red or violet eyes are quite common in some animals. For instance, the albino rabbit often has red eyes.
- Eye color isn’t just cosmetic. There are biological differences in intraocular pressure and motor skills between people with different eye colors.
How to Change Eye Color
There are ways of accidentally or intentionally changing eye color:
- Colored Contact Lenses: The simplest and safest method is of changing eye color is wearing colored contact lenses. These lenses can provide a variety of colors and effects that are temporary and reversible. Modern colored contacts change even dark eye colors. Like all contact lenses, colored contacts are medical devices that should always be prescribed and fitted by an eye care professional.
- Eye Makeup: Certain colors of eye makeup (e.g., eye shadow) enhance or slightly alter the perceived color of the eyes. Skin, hair, and clothing also reflect color back toward the eyes and impact their appearance.
- Hypnosis: Some practitioners claim that hypnosis changes eye color, although this has not been scientifically proven.
- Laser Surgery: Laser surgery changes brown eyes to blue by removing the brown melanin that covers the blue iris underneath. However, this procedure is irreversible and carries risks, including inflammation, increased pressure inside the eye, and potential vision loss. It is not a common practice.
- Silicone Implants: Silicone implants change the color of the eyes dramatically by fitting an implant over the iris. It is sort of like permanent colored contact. This method carries significant risks including glaucoma, cataracts, corneal injury, and vision loss.
- Medication: Some medications cause changes in eye color. For example, the prostaglandin analogues used to treat certain eye conditions can gradually increase the amount of brown pigment in the eyes. This is typically a side effect rather than an intended purpose of the medication, and using medication for the sole purpose of changing eye color is not recommended due to potential side effects and risks. Pregnancy also causes eye color changes in some women from the altered hormones in the bloodstream.
- Accidents: Accidents that affect the eye sometimes change its color.
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