Hazel eyes, one of the more mysterious eye colors, are as unique as they are beautiful.
But what's the science behind this one-of-a-kind eye color?
Is having hazel eyes common or rare?
And why is it that they seem to change color?
Here's the truth about hazel eyes.
Whereas people with brown, blue, and green eyes usually only appear to have one color
in their iris, people with hazel eyes have several.
Additionally, having hazel eyes is less about color and more about how color is distributed
within the iris.
And that can have some significant variation, as there's a lot at play when it comes to
how hazel eyes appear.
Specifically, the hazel pattern begins with a ring of color around the pupil, usually
brown.
Then, as you move away from the pupil and out toward the rest of the eye, the color
will shift into green, sometimes with an additional ring of amber in between.
This burst-like pattern is what makes hazel eyes distinct from green ones, which don't
have the same kind of color shift and are monochrome in appearance.
That's not to say that people with different eye colors can't have variation in their irises,
as they certainly can.
But this unique variation is how it works for the hazel-eyed folks out there.
Interestingly enough, as diverse as hazel eyes appear, there's actually only one color
in the irises of people with hazel eyes, and that's brown.
That brown color comes from a pigment that's called melanin, which is responsible for how
dark or light a person's skin is as well.
The more melanin you have in your iris and your skin, the darker both will appear.
That explains a lot.
Okay, but if there's only one color in a hazel iris, why do we see green, yellow, and sometimes
even a hint of blue?
You can chalk that up to a phenomenon called the Tyndall effect, a principle similar to
the one that works to make both the ocean and the sky look blue.
Essentially, the way that light is scattered combined with the amount and placement of
melanin determines how hazel eyes appear.
So where there's brown, there's a lot of melanin.
Where there's yellow and green, there's less melanin and light being scattered in combination.
And if there's blue, there's no pigment at all, at least not in the front layers of the
iris.
Fascinating, no?
There are plenty of models, musicians, actors, and actresses with hazel eyes out there, and
that's not surprising.
Hazel eyes are, after all unique and multi-faceted, especially in their more rare expressions.
But the reality is that hazel eyes are over-represented in the media, as not many people are lucky
enough to have this distinct phenotype.
In fact, scientists estimate that only five percent of the world's population has hazel
peepers.
That's in comparison to the 79 percent of people on earth who have brown eyes, dwarfing
every other eye color with its dominance.
And in addition to that, eight to ten percent of the world's population have blue eyes,
most of them living in various European countries like Finland, Estonia, Ireland, and Scotland.
So hazel-eyed folks, celebrate yourselves!
You're a rare bird, indeed.
Despite the fact that having hazel eyes is not very common, there are several other eye
colors that are far more rare.
Given how complex and complicated genetics can be, that's not exactly a shock, though
it certainly is an intriguing factoid you should feel free to pull out at parties.
"Question: What kind of bear is best?"
"That's a ridiculous question."
"False.
Black bear."
To start, roughly the same percentage of the world's population have amber eyes, five percent,
thanks to lipochrome, a yellow pigment that makes the iris look yellow or coppery.
However, this is more common in animals like dogs, cats, fish, and birds than it is in
humans.
After that, folks with green eyes clock in at two percent, thanks to lipochrome, low
melanin levels, and the way light scatters in the eye.
Finally, there are three eye colors that are so rare that less than one percent of the
population has them: gray eyes, red, and violet eyes, which are often only in people with
a severe form of albinism, and heterochromia, which means a person has two different-colored
eyes.
Truly those are one in a million.
You've probably noticed that often, hazel eyes appear to change color.
That's certainly the case with Tyra Banks, for example, whose eyes can appear super green
in some pictures, while they sometimes look more yellow and brown in others.
The same is true for Jada Pinkett Smith, who passed on her riveting hazel peepers to her
daughter, Willow Smith.
Of course, science has a reason for that.
Hazel eyes change color based on environmental factors such as the color of objects in a
room and the amount and type of light that is filtering into the iris.
Additionally, the color shift is also dependent on how much melanin is in the iris.
So if a person with hazel eyes with minimal melanin in their eye is wearing a green dress,
their eyes will appear greener.
And if a hazel-eyed person with a lot of melanin in their eye is wearing a brown dress, their
eyes will look more brown.
Boom, mystery solved!
In elementary school, middle school, or high school, chances are you were taught that eye
color is dependent on dominant and recessive genes, and were forced to diagram a bunch
of Punnett Squares to prove it.
It followed, then, that brown eye color is dominant over all other eye colors, including
hazel.
So according to that model of genetic determination, blue-eyed parents couldn't have brown-eyed
offspring, and brown-eyed parents could only have blue-eyed, green-eyed, or hazel-eyed
offspring if they both carried the recessive gene for those eye colors.
But as it turns out, that model was way over-simplified in some ways and totally wrong in others.
The newer, more accurate genetic research that's available about how we get eye color
shows that there are 16 genes in play that make this determination.
That means that eye color isn't determined by a simple recessive or dominant gene; rather,
it's reliant upon variations of several genes and how they interact with one another.
That's why it's possible for blue-eyed parents to have children with hazel eyes.
It's all in the genes!
"Sometimes I feel like I have comedy in my genes, along with brown eyes, soft teeth,
and weak joints."
Although having hazel eyes is a beautiful thing, there are some things that come with
this phenotype that aren't quite as lovely.
For example, brown-eyed and hazel-eyed women are more sensitive to pain than lighter-eyed
folks.
Who knew eye color could be linked to something like that?
There's no end to how unpredictable genetics are and how far-reaching the impact of them
can be on people.
But they are indeed connected, according to an article published in The Journal of Pain.
In the study, which was conducted at the UPMC Magee Women's Hospital, researchers surveyed
a total of 58 expectant mothers who were planning to deliver their babies there.
They divided the women into two groups, 24 in the group with hazel and brown eyes and
34 in the group with light-colored eyes.
The aim was to study postpartum and antepartum pain, sleep, coping behavior, and mood.
The results?
As it turns out, women with lighter eyes had an easier time giving birth than their darker-eyed
counterparts.
Additionally, they were less prone to anxiety and depression, all thanks to having less
melanin in their irises.
Wild, huh?
"What do I do?"
"Yes?"
"What do I do?"
"Nothing, dear, you're not qualified!"
"Leave it to us!"
Just as folks with hazel eyes are more sensitive to pain, they are also more sensitive to alcohol.
Though it's a little more complicated than it sounds.
In a study published in the journal Personality and Individual Differences, researchers looked
at two sets of archival data: one group was comprised of 10,860 white men, who happened
to be prison inmates, and the other was made up of 1,862 white women who responded to a
national survey.
What they found was that in both samples, light-eyed folks drank much more alcohol than
hazel-eyed and brown-eyed people.
The reason?
Lighter-eyed individuals are less sensitive to alcohol's effects, which, in turn, made
them consume more of it.
That also means that hazel-eyed folks are less prone to developing a physical alcohol
dependence.
Nothing wrong with being a little more efficient!
"Make mine a gin and Sonic, please, that's gin with a little hamburger in it.
What have I got to lose besides another foot?"
To the women with hazel eyes out there currently partnered to a blue-eyed man: your relationship
beat the odds, at least according to science.
Blue-eyed men find blue-eyed women more attractive than they do women with any other eye color,
according to a study in the journal Behavioral Ecology and Sociobiology.
Blue-eyed men were the outliers too, as blue-eyed women didn't have a preference for their partner's
eye color.
Neither did brown-eyed and hazel-eyed men and women.
So what exactly is going on here?
Fortunately, the researchers have a theory about why this is the case, and it's one which
sheds a little light on this strange mystery.
They believe that blue-eyed men's preference for ladies with the same phenotype is born
out of a need to be confident in their child's true paternity.
In other words, if the blue-eyed man's baby has blue eyes, he will be more convinced that
it's biologically his.
That's because two blue-eyed parents may be more likely to have a blue-eyed child than
not, although the latter is a possibility nonetheless.
Those of the hazel-eyed persuasion don't hail from one specific ethnic group or race.
People of just about any race or ethnicity can be lucky enough to score a set of hazel
peepers, as evidenced by the many celebs who have them.
For one, Empire actor Terrence Howard has a lovely pair of hazel-colored peepers, and
he's biracial.
Additionally, the super gorgeous model Daje Barbour has an exquisite set of hazel eyes,
and he's African American.
As for other folks, Gilmore Girls and Supernatural star Jared Padalecki has some arresting hazel
eyes, and he's white.
Movie tough guy Danny Trejo also has an especially lovely hazel-green eye color, and he's a proud
Latino.
South Korean actress Lee Sung Kyung is also in the hazel club, proving that hazel eyes
are truly universal.
For some of us, the eye color that we present with at birth is the same that it will be
for the rest of our lives, but that's not the case for everyone, according to an article
posted by McGill University For white or other less-melanated people, it's not uncommon at
all for babies to be born with blue eyes that can later turn different colors, including
hazel.
That's because it can take a while for melanin to be deposited into the iris, which usually
is completed after about six months.
At that time, a baby's eyes can turn green, hazel, gray, or brown.
And in some cases, it can take much longer for eye color to fully develop, sometimes
into adulthood.
That's just one more mystery that melanin brings to the genetic table.
Although having light-colored eyes is considered to be quite beautiful, it can come with its
own set of risks and vulnerabilities.
To that end, it's important to point out that people with hazel eyes who have more melanin
in their eyes are less prone to some risks than hazel-eyed folks with super light-colored
eyes.
It's just the luck of the draw.
Specifically, if you have light-colored eyes, including light eyes with a hazel pattern,
you're more at risk for some kinds of cancer.
That's because the lighter your eye color, the more light-sensitive your eyes are, so
you need to take precautions.
Dr. Ruth Williams, an ophthalmologist at the Wheaton Eye Clinic in Chicago, says:
"Clinically speaking, people with blue or light-colored irises do tend to be more light-sensitive.
This is likely due to the sparsity of light-absorbing pigment in the eye.
The more pigment you have, the less light gets through the iris...People with light
iris color need to be diligent in wearing UV-protected sunglasses."
So in other words, protect your hazel peepers, especially if they're greener than they are
brown.
It's just better to err on the side of caution, and stay safe.
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