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Gray eyes, belonging to 3% of the global population, are the rarest and most mysterious eyes of all.
We all know that gray eyes are determined by two different factors. However, have you ever wondered what might be the reason behind the rarest and most mysterious of all eye colors?
One of the primary determinants of eye color is the pigmentation of the iris as well as the modulation of light scattering by the turbid substrate in the stroma of the iris, depending on frequency. Humans' eyes have a wide range of iris pigmentation, ranging from light brown to black according to their pigment epithelium, their stroma, and the level of melanin they contain. It is the Tyndall scattering of light in the stroma that accounts for the color of blue. green, and hazel eyes. At this point, you might have a slight idea as to the reasons for gray eyes. Well, let's find out if you are correct!
How did humans even evolve into developing eye colors like gray? Read on to find out!
Today, the human population has evolved to bear eye colors in different shades. However, did you know that this wasn't really the case during ancient times? Ancient people are believed to have only had dark brown or almost black eyes.
So, what might have caused such drastic changes? Although, a lot more evidence needs to be gathered, most scientists believe that the selection for light eye colors might somehow be related to the relaxation of selection for dark skin tones.
As our ancestors migrated to different parts of the globe, the pressure for selecting dark skin became less intense. The choice for dark skin and dark eyes was no longer necessary for survival for human ancestors who settled in regions that we now know of as western European nations. Unlike Africa, these regions were located at much higher altitudes, meaning no direct and harsh sunlight. With such varying conditions, the genes started mutating in order to adapt to this new environment. This also explains the reason why gray eyes are most common among people with European ancestry.
So, we already know how gray eyes are pretty rare in terms of the global population but just how rare are they? Let's find out!
Most common in northern and eastern Europe, gray eyes are pretty rare and can only be found in about 3% of Earth's population. After green, gray is the second rarest eye color that can mostly be found in people with European ancestry. However, in addition to the Europeans, this eye color can also be found amongst Shawias of Northwest Africa, whose ancestral homeland can be traced back to the Aures Mountains, West Asians, Middle Easterns, Central Asians, and South Asians.
Gray eyes have also been mentioned in Ancient Greek scriptures and are associated with Athena, the Goddess of Wisdom, who too had gray eyes. Twenty-five percent of Greeks have lighter eye colors, including gray, green, or blue eyes.
So, what causes gray eyes, and why are they the rarest of all?
It is the amount of melanin in the iris that determines the color of the eye in all eyes. A large percentage of the color of the eye is determined by the amount of melanin the eye contains. Irises are made up of two tissue layers, one on the front and the other on the back, that are joined by the stromal tissue in the middle. The iris of darker eyes contains melanin in a higher concentration in both the front and the back layers, resulting in less light being reflected back out, making the eyes appear dark- brown or black. In contrast, melanin is less abundant in lighter eyes and is located in the back layer.
The exact reason behind gray eyes still remains unknown. Nevertheless, scientists believe that the genetics behind gray eyes are very similar to that of the genetics responsible for blue eyes. It may be that the front layer or the stroma of gray eyes contains just enough melanin that allows for dimming the light wavelengths of blue that are reflected back. Gray eyes also come in different shades; light and dark grey. With higher melanin content, the eyes appear dark grey, while lower melanin means lighter gray eyes.
Grey eyes, just like blue eyes, have a relatively clear stroma at the front, while the back has a dark epithelium. According to scientists, the fibers in the stroma, a thin layer in the iris, scatters light in a different directions, thus, it makes the iris of the eye appear gray. The difference between gray and blue eyes is also believed to be because of the varying levels of collagen in the stroma.
The light reflected from the epithelium goes through Mie scattering (which is not strongly frequency-dependent) rather than Rayleigh scattering (where shorter wavelengths of light are scattered more).
This process is also similar to the phenomenon that affects the sky. When the sky is clear, the color of the sky is blue due to the Rayleigh scattering of sunlight by small gas molecules, but when the sky is cloudy, the color changes to gray due to the Mie scattering of large water droplets. Gray eyes, however, have been found to have a higher concentration of melanin at the front of the stroma as opposed to blue eyes.
Due to lesser amounts of melanin, people with gray eyes are vulnerable to certain health risks. Let's find out what they are.
Although melanin is a pigment that gives color to your skin, eyes, and hair, it has a lot more functions than just bringing colors to your life. Melanin is a natural sunscreen that protects you from UV light and reduces the risks of cell damage. In addition, melanin scavenges free radicals that are induced by light. Dark skin and dark eyes contain higher amounts of eumelanin, which is more photoprotective than pheomelanin.
Furthermore, the basal epidermis of black skin has a higher amount of melanin than that of white skin. Despite similar levels of melanin in the RPE between different races, black people's choroidal melanin is significantly higher than that of white people. An inflammatory response linked to the immune system is triggered by acute UV exposure, which causes dermal blood vessels to dilate.
There are 33 times more erythema cells in black skin than in white skin, which can be quantified as the minimal erythema dose. Dermal vessels are reduced in size and number due to chronic sun damage, which is most pronounced in light skin. The choroidal blood flow is also reduced in AMD, probably as a consequence of oxidative damage to choroid endothelial cells.
Since the amount of melanin present in one's eyes is responsible for protection from UV rays and bright sunlight, this makes lighter eye colors, including gray eyes, a lot more sensitive to the sun than darker eye colors. It has also been found that about 27 percent of vitiligo patients have blue or gray eyes, compared with 52 percent of Americans that had non-Hispanic, European ancestry who did not have this skin disorder.
Lighter-colored eyes, including gray eyes, have a higher chance of cancer. In fact, light-eyed people are more likely to develop melanoma of the uvea, the middle layer of the eye, over the course of their lifetimes because lighter eyes have less pigment to shield them from harmful ultraviolet rays. This means that lighter-colored eye people should always wear UV-protected sunglasses. The incidence of the disease in black Americans, who tend to be brown-eyed, is estimated to be less than one-eighth that of white Americans. Melanoma of the uvea is an extremely rare cancer affecting approximately six out of every million adults annually.
People with gray, green, or blue eyes are more likely to be fair-skinned meaning a higher risk for skin cancers, although this might not directly be linked to vision.
Let's now take a look at some other interesting facts related to gray eyes.
Did you know that recognizing gray eyes is not as easy as one might think? Gray eyes can easily be mistaken for blue eyes and often get grouped together with blue eyes by scientists. However, on looking carefully, one can surely differentiate between gray and blue eyes.
Gray eyes have also been found to have gold and brown flecks in them. Gray eyes can also change their hues depending on different lighting conditions. Gray eyes can also appear gray, blue, and even green in certain situations depending on what the person is wearing and the kind of light they are exposed to. Eye color can also change depending on the person's mood because of the alterations in the size of their pupils that can further compress the color of the iris.
Although having eyes that are the rarest of all is a blessing, it still can have disadvantages, in fact, a lot more than darker eyes. Having gray eyes means UV-protected sunglasses are a necessity. People with gray eyes need to be extra careful about their eyes and need to constantly make sure to not expose their eyes to the light.
Light-eyed people are also less sensitive to medications. However, one good thing that comes with this lesser sensitivity is the fact that they are also less sensitive to pain, meaning they can endure pain more than people with dark eyes.
People with gray eye colors are also said to be of weak intellect, and devoid of wit. However, men with light eyes are also said to be more faithful in comparison to men with darker eyes. However, this is not the same when it comes to women with light eyes; they are said to be not that pleasant and to be greedy. From the 1896 book 'What They Say in New England: A Book of Signs, Sayings, and Superstitions', an old children's rhyme describes the meaning of each eye color. In this rhyme, once again, gray-eyed people are demonized as the book read 'Gray eyes, greedy; Blue eyes, beautiful; Black eyes, pig-a-pies, sure to tell lies'.
The ancient Greek goddess, Athena, was also said to have gray eyes. Athena is the Greek goddess who is associated with wisdom and naturally, ancient Greeks associated people with gray eyes with great wisdom. Gray-eyed deities were also associated with owls, which are still regarded as symbols of knowledge in the modern world.
Dreaming of someone with gray eyes? That too might have some meaning. Dreams are interpreted differently depending on the color of an eye, according to 'The Dictionary of Dreams: Every Meaning Interpreted'. We should take the interpretations of dreams with a grain of salt since dream interpretation is not an acknowledged field of science. It has also been reported that brown eyes represent deceit and perfidy while blue eyes represent a lack of ability to see things through. When you only see black and white in your dreams, dream interpretation can seem pretty confusing. If you dream of someone with gray eyes, it is more than likely just a dream.
At your next game night, you definitely want your gray-eyed friends on your team. In competitions, gray-eyed people have a distinct advantage. Research shows that gray-eyed people are more competitive, which makes them great teammates (if you're looking to win). The study, which was published by 'Current Psychology' and summarized by Joe, showed that people with lighter eyes are more prone to be skeptical and egocentric in addition to being more competitive.
Why are gray eyes so rare?
Gray eye colors are the rarest eye colors after green. Although the rarest eyes are green, anecdotal reports suggest gray eyes are even rarer.
Is having gray eyes bad?
Although gray eyes are rare and special, they also come with many disadvantages such as sensitivity to light and bearing more risk of cancer.
Are gray eyes recessive?
Gray eyes are believed to be more of the recessive gene than dominant.
How do gray eyes happen?
Gray eyes are mostly caused by a reduced amount of melanin in the eyes.
Why do grey eyes change color?
Gray eyes change color depending on the mood of the bearer or the light intensity.
What is the origin of gray eyes?
Scientists believe that people had darker eyes but gradually transformed into having lighter eyes once they started migrating to regions with higher altitudes, resulting in mutation that lessened the pressure to adapt to the regions with harsher climate conditions.
What ethnicity has gray eyes?
The majority of gray eyes are found in northern and eastern Europe.
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