- [Narrator] They say the eyes
are the window to the soul, but just how special are yours? You're probably familiar
with the same old shades, but believe it or not, there
are people with silver, violet or even multi-colored
eyes out there. Stay tuned for some of
the rarest eye colors spotted in humans. (light music) Number 10, ice blue. You probably know at least
one person with blue eyes, but as it stands, only about eight to 10% of the world's population can say they have a pair of blue blinkers. In fact, a study conducted by
the University of Copenhagen in 2008 revealed that all blue eyed people are descendants of the
first light eyed humans who emerged in Southeastern Europe around 10 thousand years ago. Eye color is determined
by the amount of melanin in your iris, which is
made up of the epithelium, the back of the iris, and the stroma, which is positioned in the front. While the epithelium
contains dark brown pigments, the stroma can sometimes be
totally devoid of melanin, making it translucent, which
is the cause of blue eyes. Interestingly, natural blue
pigment doesn't actually exist. It all has to do with the
way light enters the eye. While melanin absorbs light
and presents it as brown, blue eyes scatter light
back into the atmosphere in what is known as a Tyndall Effect, similar to how the sky
sometimes appears blue. This 10 thousand year old genetic mutation affecting the OCA2 gene created a switch which can turn off the
production of melanin, meaning the clear stroma presents as blue. Blue eyes are even less common in people of African American
descent, and in such cases, the iris can often appear as a piercingly beautiful ice blue. Number nine, amber. 79% of us have brown eyes, but
there is one rare variation which only 5% are lucky enough to possess, known as amber eyes. People with truly amber eyes
have a distinctly golden iris, which can range from a strong yellow hue to a coppery russet tint, giving someone a seriously
penetrating gaze. This unique coloring is a
result of reduced melanin levels alongside the increased presence of a yellowish pigment called
lipochrome, or pheomelanin. Once again, the interference
of light also has a lot to do with the way we perceive amber eyes through the process of
Rayleigh Scattering, which determines the way we see colors based on how light is reflected. In some conditions, amber
eyes might seem closer to brown or hazel, but
under natural lighting, there's no mistaking their
almost mythical golden glow. This rare variation is
sometimes also referred to as wolf eyes, because such
a vibrant coppery tint can also be commonly found in wolves, as well as animals like
eagles, owls and fish. Research shows that this
color is more commonly found in countries in Asia and South America, but true amber eyes are
still hard to come by, so if you have them, you can consider yourself
extremely special. Number eight, green. Green eyes are probably one
of the first that come to mind when you're asked to list
some of the most common colors humans can have, but people
with genuinely green eyes only make up about 2% of the planet. It's easy to confuse
green eyes with hazel, which, while still very rare, contain distinct flecks of brown due to a concentration of melanin on the outside of the iris, making them seem almost multi-colored. Truly green eyes lack
this characteristic burst of brown or gold radiating
outwards from around the pupil, and instead have a more
solid emerald shimmer, which couldn't be mistaken
for blue or brown. Much like blue eyes, a natural green pigment doesn't
actually exist in humans, so what we see is created by a process called Structural Coloring. In this case, the iris
has low levels of melanin alongside a small amount
of yellow pheomelanin, meaning that when
Rayleigh Light Scattering gives off a blue hue, this mixes with the
pheomelanin to create green, just like mixing primary
colors in art class. In some parts of the world, green eyes are completely absent, while this beautiful variation
can be more commonly found in places like Northern
and Central Europe. Green eyes also usually
occur more often in women, and some notable examples
of green eyed celebs include Adele, Emma Stone
and Amanda Seyfried. Number seven, silver. Claiming to have silver
eyes might arise suspicion that you've inherited
some supernatural genes, but about 1% out there do
in fact have gray eyes. An individual with
these mysterious peepers can have an iris which
ranges from a cold steel to a smokier blue hue. But contrary to popular belief, having gray eyes isn't
just a more creative way to describe a considerably
pale blue shade. Although significantly low melanin levels are again responsible for
the translucent appearance of the stroma, the iris
does not reflect blue light due to a certain amount
of excess collagen. The presence of this collagen interferes with the way light reflects in the iris, and the appearance of blue hues through the Tyndall Effect
is therefore blocked, presenting a more solid
gray color instead. In genetics, individuals are
also said to have gray eyes when the dominant pigment
inherited from their parents falls between blue, brown and green. Anthropologists theorize
that early gray eyed humans lived around the vast
mountain system of Eurasia, and nowadays, lucky people
with this rare eye color are most commonly found
in Northeastern Europe. Number six, black. Your pupil, which is essentially a hole located within the iris, appears black because light rays
entering it are absorbed by tissues inside the eyeball. But is it possible to be born
with completely black eyes? The short answer is no,
unless you're a demon, because there isn't a
naturally occurring pigment capable of darkening your eye entirely. But there are a couple of reasons why a select few individuals might appear to have black eyes. If staring into someone's eyes seems more like looking into an endless black hole, the likelihood is that they just have an extremely dark brown iris,
which is hard to distinguish from their pupils in any lighting. The only naturally occurring color pigment in the iris is brown, and
this comes from melanocytes, miniature melanin cells which absorb light rather than scattering it. This means that an
overproduction of melanocytes corresponds directly with darker eyes, so people with dark brown to black eyes just have more melanin in
their iris than the rest of us. A bazaar condition called
aniridia can also be responsible for seemingly black eyes
though, as a chromosome mutation causes an almost complete
absence of the iris. In reality, there is a
small ring of iris tissue, but the grossly enlarged pupil makes it impossible to spot. This rare disorder affects
around one in 100 thousand people and can cause side effects like light sensitivity and blurred vision. Number five, violet. You might have heard of
the popular Internet myth about a genetic mutation
called Alexandria's Genesis, which supposedly causes
purple eyes during puberty, while others might feel nostalgic over actress Elizabeth
Taylor's famous violet eyes. But is there any truth behind
his sought-after color? Simply put, the chances of actually having such an unusual characteristic
are second to none, because there's no purplish
pigment capable of creating it. However, in certain cases,
like Elizabeth Taylor's, the palest blue eyes with
a tiny amount of melanin can have a violet tinge when certain light also reflects the blood
vessels within the eye. Interestingly, Taylor's amethyst eyes were also enhanced by
a rare genetic mutation called Distichiasis,
which caused her to have a freaky double row of eyelashes. People with albinism also
have a much higher chance of having violet-presenting eyes, because of the extreme lack
of pigmentation in their skin and therefore melanin in their iris. A reduced number of melanocytes can cause almost colorless eyes, which are easily affected by sun damage, giving them a more purplish hue. Albino fashion model Natasya Kumarova has fascinatingly beautiful eyes, which can appear violet
under certain lights. But for the rest of us, it
seems like having purple eyes will remain a pipe dream. Number four, red. For centuries, humans
have associated red eyes with all things evil, and although we're used to seeing red eye in flash photography,
having crimson hued vision is nothing but a work
of fiction, or is it? As we've learned, brown
is the only pigment that can occur naturally within the iris, while all other colors are
a result of varying degrees of light reflection, but red
is a little more complex. In fact, it's virtually
impossible for the average person to have genuinely red eyes. This is because for the iris to have a distinctly pink shade, there needs to be a
complete lack of melanin and collagen deposits, which
allows light to bounce off the back of the eyeball. The red color we then see
is a direct reflection of the color of the retina
and blood vessels in the eye, which also makes them
extremely light sensitive. It's impossible for light
to exit the eye this way under normal circumstances,
so like violet eyes, this phenomenon almost exclusively exists within people with albinism. This unusual process also
occurs in albino animals, like white rabbits, albino
hedgehogs or certain snakes, all of which have blood red eyes due to a lack of pigmentation to control and filter out light. Number three, different colored eyes. Although a tiny portion
of the world's population do have totally unique eye colors, most of us will have brown or blue eyes. But there are some lucky individuals who ended up with one of each. This mind-blowing phenomena is
known as Heterochromia Iridum and it occurs in less than
1% of the world's population. While incredibly rare,
the unusual condition can be traced back to ancient times, and there's even record of an
Eastern emperor, Anastasius, who was nicknamed Dicorus, which literally means two-pupiled because he had different colored eyes, one blue and one brown. In most cases, this unique
characteristic is hereditary, but it can also be acquired later in life through illness, eye trauma, use of certain medications
or even old age. Surprisingly, heterochromia
iridum occurs more commonly in dog breeds such as huskies,
but us humans can develop the striking feature
due to varying factors. During infancy, when eye color
is still subject to change, the affected eye might be
hyperpigmented, making it darker, or hypopigmented, causing
it to appear lighter, due to an uneven
concentration and distribution of melanin within the iris tissues. Heterochromia iridum also happens to be one unlikely thing Mila
Kunis, Josh Henderson and Michael Flatley all have in common, so they're rich and famous
and they get cool eyes. Number two, multi-colored eyes. If there's anything cooler than having two different colored eyes, it's mixing those colors into one, right? This unbelievable
variation is another strain of heterochromia iridum known
as sectoral heterochromia, and it's just as rare. In fact, you'd be lucky
to encounter someone with this unique condition
in your lifetime. In these unusual cases,
the distribution of melanin across a single iris is
distinctly non-uniform, which means that light is
both absorbed and scattered from different areas
of the stroma at once. This mostly manifests itself
as a characteristic splash of brown or blue, which stands out against the dominant shade. But occasionally, a
near 50/50 distribution can result in a breathtaking iris, which is split down the middle. Although officially
classed as a rare disease, sectoral heterochromia,
alongside heterochromia iridum, poses no real health risk,
so anyone blessed with it can pride themselves on
being totally unique. Plenty of celebs even have varying degrees of this multi-colored phenomenon
if you look close enough, including Benedict
Cumberbatch, Henry Cavill and Kate Bosworth. Number one, cat eyes. Regular humans with catlike
eyes may seem like a plot for the most boring
superhero movie ever made, but believe it or not, there
is one extremely rare condition which can make someone's
eyes seem totally non-human. Cat eye syndrome affects one
in around 100 thousand births and is commonly caused by
a chromosome abnormality known as an inverted duplicated 22. This means that each cell has
at least one extra chromosome made up of genetic material
from chromosome 22, which leads to the characteristic
size of cat eye syndrome, the most visible being a
distinctly elongated pupil, much like a feline or reptile. This defect is scientifically
known as an iris colomba, which is basically a hole
in the structure of the eye present during the early
stages of pre-natal development that fails to close. The often keyhole shaped pupil
can seem like it's melting into the iris, making the
color of the eye itself seem swirled or spotted from a distance. The condition occurs
sporadically during the formation of an egg or sperm, and can
then be genetically passed down. Depending on the severity
of the deformation, affected individuals may
experience impaired vision or even loss of sight, so maybe
this is one rare set of eyes you don't wanna have. Do you have a rare eye color, or do you wish your eyes
were a different color? If so, which one? Let me know in the comments
below, and thanks for watching. (light music)
