Eye Color

Humans originally had brown eyes until genetic mutations started making variations. No two eyes are identical, not even your own.

Your eye color & design is as unique as your fingerprints. Several gene variations all contribute to giving each of your eyes a particular design and shade of color (or colors plural if you are heterochromatic) that nobody else has. Not even your own two eyes are identical. Originally all humans had dark brown eyes (along with dark brown skin) which helped to reflect some of the harsh rays from the sun. As groups of humans migrated out of Africa and up into Europe, where there are seasons with less sunlight and the land is further away from the direct sunlight of the equator, there was no longer a need for so much protection from the sun’s harmful UV light. This is where the first mutation in human eye color took place. Sometime between 6,000 and 10,000 years ago the first blue-eyed person was born, from which all other blue-eyed people are descendant.

Eye Colors

Our skin and hair is colored using the brown pigmentation called melanin. The back of our irises also contains melanin which gives our eyes color. Melanin is brown, and so brown eyes using brown pigmentation is easy to understand. Light enters the iris, the melanin absorbs some wavelengths of light and reflects back out the necessary waves to make the color brown, making brown eyes brown.

You would think then that blue eyes use blue pigmentation, but they don’t. Blue eyes use the same brown pigmentation as brown eyes but in lesser quantities. The other trick is that, since eyes are three dimensional, blue eyes absorb and scatter waves of light differently than brown eyes. The longer light wavelengths (reds & oranges) get broken up inside the eye and only the shorter wavelengths (blues) get reflected back out making blue eyes look blue. This scattering effect of allowing/blocking certain wavelengths is also what gives the sky color.

Even though all colors of eyes use brown melanin, variations in the construction of the eye and how it absorbs & scatters various light waves makes an iris a certain color.

Brown, blue, gray, hazel, green – all eye colors use some amount of brown melanin combined with various ways of scattering & absorbing light to make whatever color the eyes are. Depending on the severity of their condition, humans with albinism can lack the necessary pigmentation to make their irises as opaque as other people’s. Irises that fail to block excessive light from entering the retina can cause a variety of vision problems including extreme sensitivity to bright light.

What does eye color “do”?

As for any potential purpose, eye color doesn’t “do” much. Unlike other genetic traits which evolution embraced because they helped our chances of survival, eye color variations seems to be largely perpetuated through romantic desirability. People find certain eye colors more attractive and so the genes for those colors live on. Your eyesight isn’t any better or worse because of a certain color eyes. Light travels through the pupil to the retina and so the color of the iris doesn’t change what you see. This is why cosmetic contact lenses can change your eye color without changing what you are seeing – they are only covering the iris.

There are some minor effects of having different eye colors. Because of how light is scattered and absorbed inside the eye, lighter colored eyes are sometimes more sensitive to bright light leaving some to squint more as well as needing to wear sunglasses more frequently. Driving at night can also be difficult because the glare from oncoming traffic can be more harsh. People with light colored eyes are more likely to develop macular degeneration, but people with brown eyes are more likely to develop cataracts. Finally, people with light colored eyes tend to perform better in sports where they control the hand-eye coordinated action such as in bowling, golfing, pitching, etc. Brown-eyed people tend to be better at sports where they react such as hitting a ball, boxing, playing defense, etc.

Added info: Getting reliable statistics on eye colors is difficult. That said brown eyes are the most common color type in the world at somewhere between 55-79%. Gray eyes seem to be the rarest at less than 1%. The eyes of some babies start out as blue but eventually become green or brown as their eyes develop more melanin. Few blue-eyed babies will have blue eyes as adults.

Liz Taylor was said to have violet eyes, but in reality she had blue eyes but with a genetic mutation to have double eyelashes which made her eyes look more purple. David Bowie was known for having two different colored eyes, but this was also an illusion. When he was 15 he got in a fight over a girl and his left eye was damaged leaving the pupil permanently dilated. This gave the impression that he had one black eye and one blue eye, but in reality both of his eyes were blue.

Liz Taylor and David Bowie both had remarkable eyes.

Autumn Colors

Leaves change colors in autumn because the temperature drops and the hours of sunlight diminish.

The leaves of deciduous plants change color as summer ends and autumn begins. Cooler temperatures and fewer hours of sunlight trigger chain reactions in how plants operate. When leaves are green it’s because of an abundance of chlorophyll which absorbs sunlight and produces simple sugars to feed the plant. Autumn’s seasonal changes tell plants to produce less chlorophyll. Autumn also tells plants to start producing special corking cells at the base of each leaf stem. These cells reduce the flow of nutrients (including chlorophyll) into or out of the leaves and eventually completely seals off the leaves from the branches allowing them to fall off.

So as chlorophyll production decreases, and leaves become sealed off from the rest of the plant, leaves can no longer stay as green as they were. What color they become depends on the plant.

Yellows and Oranges

Chlorophyll is the big green machine, it outweighs all other chemicals present in a leaf. As there is less and less chlorophyll present, the carotenoids that have been present the whole time begin to be visible. These chemicals give leaves different shades of yellow and orange depending on the plant. Carotenoids are also what make carrots orange.

Reds

Unlike carotenoids which are present in leaves all year, anthocyanins are pigments specially produced just for autumn. The end of summer triggers the production of anthocyanins which give leaves the deeper colors of reds, purples, and even blacks. Anthocyanins also are what give cranberries, cherries, and blueberries their colors.

Top Down

Much like a corporation, change takes place from the top down. Higher elevations see leaves change colors earlier than lower elevations. This is because higher elevations reach the cooler temperatures necessary to trigger the change before the same plants in lower elevations which have warmer temperatures.

A tree turning color from the top down.

Change also takes place top down in another way. The top leaves of a plant will typically begin changing color before the bottom leaves. This is because the top leaves are furthest from the roots and, since it takes more effort to send chlorophyll to the top of a plant, the top leaves will start losing their green color first.

“Autumn is a second spring when every leaf is a flower.” ― Albert Camus

Orange the Fruit, Orange the Color

Orange the color was named for orange the fruit, not the other way around.

The English word for the color orange has a trail back through a few European languages but has its origins in the Sanskrit “nāraṅga” which was the name for the orange tree. Oranges the fruit came to Europe through Spain with the Moors, who in Arabic called the fruit “nāranj”.

From the Arabic name for the fruit, “nāranj” became “narange” in English in the 14th century and by sometime in the early 16th century the spelling became “orange”, and was then used to describe things that were the color of the fruit.

Some confusion may apply

Without a name for a color, cultures use the words they do have to describe the things around them. Because English didn’t have a word for the color orange until the 16th century, some things that are orange (or orange-ish) were labeled as red because it was the closest color that English had a word for. “Red” hair and the robin “redbreast” for example are really more orange than red, but they were named before English had the word “orange”.

Describing colors before language has name for those colors had been a problem across cultures for a long time. The Ancient Greeks had a very limited palette of color names to choose from. For example, there seems to have been no word in Ancient Greek for the color “blue” so in Homer’s The Iliad and The Odyssey he describes both the sky and the sea as being a wine / bronze color. Even stranger, he also describes sheep as being wine colored.