Science is a strange and fascinating world. If it’s not contributing to amazing inventions, radically new technologies, or trying to solve the world’s medical mysteries, it can also reveal facts we don’t always like.
If it doesn’t prove that the dinosaurs all looked like giant chickens and did not roar, or Take away Pluto’s planetary statusscience gets personal to prove that people with “uniquely” colored eyes actually just have brown eyes.
That’s right – everyone started out with brown eyes.
What Causes Brown Eyes?
Blue eyes? Green eyes? Brown eyes? Grey eyes? Science says your eyes are actually brown.
dr. Gary Heiting is a licensed optometrist and editor-in-chief of an eye care website called All About Vision. According to Heiting“Everyone has melanin in the iris of their eyes, and the amount they have determines their eye color. There is really only (this) one type of pigment.”
Melanin is the pigment that is in your hair and skin as well as in your eyes, and the color is – you can probably guess it – actually dark brown.
Melanin absorbs light, so if a lot of it is present, it can absorb more and appear darker. Hence, why darker hair, skin tone and yes, even eyes contain higher amounts of melanin.
Heiting adds, “It’s an interaction between the amount of melanin and the architecture of the iris itself. It’s a very complex architecture.”
When in an eye, higher levels of melanin cause the iris (the colored part of the eye) to look brown because it absorbs a lot of light and reflects less light. Conversely, if you don’t have a lot of melanin in your eyes, they will appear lighter because they reflect more light.
The color brown is a result of a high concentration of melanin in the iris, which means that more light is absorbed and less light is reflected.
People with brown eyes make up between 55 and 79 percent of the world and are the most common eye color. Green is the rarest eye color.
Does eye color change in babies?
Of all eye colors, blue eyes are said to have the least amount of pigment. So while a baby’s eyes may appear blue when they are born, they are likely to develop more melanin later on, making their eyes darker in color.
Heiting says, “As a baby develops, more melanin builds up in the iris.”
The actual process is called “scattering,” and the light that bounces back to your eye bounces off shorter wavelengths that appear on the blue side of the spectrum of light color.
What is the difference between brown eyes and hazel eyes?
Brown eyes and hazel eyes normally fall into the same category when in fact they are very different. The melanin levels of brown and hazel colors are very unique compared to other eye colors such as blue.
Both hazel and brown eyes have normal levels of melanin in their posterior layer. But on the anterior layer, brown eyes have a heavy melanin presence of brown while hazel eyes have a higher presence of green.
Therefore, people with brown eyes have two dominant pigments (eumelanin and pheomelanin) that fight with each other, constantly changing the color.
What’s so special about brown eyes?
Apparently, people with brown eyes have great health benefits, all because of their eye color.
For example, people with brown eyes are less likely to develop macular degeneration due to age compared to those with light eyes. People with brown eyes also have a lower risk of type 1 diabetes or melanoma of the eye compared to those with lighter eyes.
However, people with dark eyes are more likely to develop cataracts. A study from the early 1990s conducted research into the risk factor that people with brown eyes develop cataracts. Researchers found that brown-eyed people are more than twice as likely to develop cataracts in old age than light-eyed people.
The study was published in the American Journal of Ophthalmology, where researcher Robert Cumming, Ph.D. explained: “According to our research, people with dark eyes are at greater risk, whether they are sunbathers or not.”
Are brown eyes attractive?
1-800-Contacts conducted a survey in September 2019 to determine the most attractive eye color in the US They surveyed 1,000 people of different genders, ages and sexualities to find out how people perceive eye color.
The study found that gray eyes were both the rarest and the most statistically attractive eye color. Hazel and green were good seconds. However, brown eyes turned out to be the most common and yet the least attractive to the survey participants.
But don’t let that get you down. Apparently, because of the way brown eyes are created by spots of color, no set of brown eyes is the same as another person’s. Therefore, brown eyes are unique in their own way.
Why do I have dark brown eyes?
According to the American Academy of Ophthalmology“The iris is made up of two layers of muscles and different types of cells. In most people, the back layer contains at least some brown pigment, even if their eyes don’t look brown. In people with brown eyes, the front layer of the iris has also some brown pigment in its cells. The more melanin there is in the iris, the darker brown it will be.”
The color of a person’s eyes can also be determined by their location.
Dark brown eyes are most common in Africa, East Asia, and Southeast Asia; hazel eyes are found in western Asia, America and Europe. This is due to the high melanin content which is meant to protect the hair and skin from the sun in these warmer regions.
One theory is that the evolution of eye color can also be traced back to earlier times. People used to need more melanin in their bodies to protect them from warmer climates, but when people moved to less sunny locations, that need has changed.
Related stories from YourTango:
Another theory suggests that it could be the cause of a common mutation† “It’s believed that blue eyes came about that way, but it could just be the de-emphasis on the need for all melanin,” Heiting says.
There are 16 genes that determine eye color, but two are really essential.
Many once believed that eye color was determined solely by one gene — and those are, yes, genes to do play a role in eye color. However, there are several genes that play a role in determining eye color.
“Different genes affect eye color. You can’t just predict that,” adds Heiting.
There is in total 16 genes that determine eye colorbut it is most commonly attributed to two adjacent genes on chromosome 15, protein 2 (HERC2) and ocular albinism (i.e., oculocutaneous albinism II [OCA2]†
There’s the substance that produces OCA2, which helps determine eye color: P protein, which works to mature melanosomes. Melanosomes are a type of cellular structure that work to store and produce melanin. Because brown eyes are high in melanin, they have higher levels of P protein.
HERC2 has a region called intron 86. Within this region is a DNA segment that controls OCA2 gene activity. Basically, HERC2 turns the OCA2 gene off or on when needed. With a higher OCA2 activity, your eyes will be darker.
So yeah, the reason your eyes look green, brown, gray, or any other color is probably because you don’t actually have melanin in your irises.
More for you on YourTango:
#Science #proven #everyones #eyes #brown