Why are certain eye colors rare? Eye color is a polygenic trait. This means it is a complex characteristic determined by the interaction of multiple genes inherited from parents.
Certain eye colors are rare partly because only very few people are carriers of these rare eye-color-genes. Secondly, rare eye-color-genes are recessive. This means they are overridden by other dominant eye-color-genes.
Not much is known about the exact set of genes responsible for a person ’s eye color. Research is still to isolate the exact set of genes that determine a person ’s eye color.
The iris is the part in our eyes that gives us our eye colors. Eye color is decided by two factors; the pigmentation of the iris and the scattering effects of light in the iris. The iris contains two pigments; a brown pigment called melanin and a yellowish pigment called lipochrome. The higher the concentration of melanin in the cells of the iris, the darker the eye color.
There is often some debate on what the rarest eye color really is. With little or no dispute, the contenders for the rarest eye color in the world are green, amber, violet, red and black.
Green Eyes
Green eye color is a very likely the rarest eye color in the world. Only very few people are born with green eyes. Green eyes are most common in northern and central Europe.
Irises of green-eyed individuals have only a small amount of melanin. Their irises also contain moderate amounts of lipochrome (a yellowish pigment). Very low concentration of melanin in the iris gives it a lighter and bluish color. The mixture of bluish color and the yellowish from lipochrome gives rise to the green eye color. The intensity of the green eyes can change slightly due to scattering effect of light in the iris. That is why a person ’s eye colors can appear slightly different in different lighting conditions. This phenomenon called Rayleigh scattering. The human eye has no green or blue pigment.
Amber Eyes
Amber eyes are often referred to as ‘wolf eyes’ because of the strong golden and yellowish color with a copper tint similar to that seen in the eyes of wolves. Besides wolves, amber eye color can also be found in other animals.
This eye color is due to a low concentration of melanin and a very high concentration of lipochrome deposited in the cells of the iris.
True amber eyes are extremely rare. Most people have only seen about a couple of amber-eyed people in their entire life. Amber eye color is as rare as green eyes and potentially rarer.
Violet and Red Eyes
Let us now consider colors coming from other parts of the eye other than the iris. In this case, violet and red eyes without much dispute will be considered the rarest eye color in the world.
Violet Eyes
True violet eye color occurs mainly in people with albinism. This is a condition characterized by lack pigments in cells. Violet eyes are as a result of lack of melanin in the cells of the iris. This eye color is as a result of light reflected back from blood vessels at the back of the retina. A mixture of red color reflected off blood vessels in the retina and the bluish color of the iris due to lack of melanin gives the violet appearance. Less than 1% of the world ’s population are born with violet eyes.
Ever wonder why you have red eye in some of your photographs? This phenomenon is similar to what happens in violet eyes. This is due to light rays from the flash of the camera being reflected off the blood vessels of your retina. It is often worse in people with lighter eye colors. This is because people with lighter eye colors have lesser melanin to reabsorb some of the light from the camera flash.
Red or Pink Eyes
Red or Pink eye are mainly found in people with albinism. Albinos lack pigments in their bodies hence their eye appear violet. Red eye color is commonly due to leakage of blood into the iris. This type of leakage is rare under normal circumstances.
Black Eyes
Black eyes are due to a large quantity of melanin deposited in the iris and this leads to extremely dark brown eyes that appear black. The more melanin you have deposited in your iris, the darker your eye color will be.
Many people say that true black eyes do not exist. They argue that black eye color is rather very dark brown color, so dark that it appears black.
So, what is the rarest eye color in humans?
There is no eye color that has been fully agreed upon as the rarest eye color in the world. Green-eyed and amber-eyed people are both extremely rare. The rarest eye color is different in different geographical locations. In some parts of the world green eyes are rarer than amber eyes and vice versa.
Overall, a lot of people consider green as the rarest color in the world. A lot of others consider amber as the rarest eye color in the world. Therefore you will not be far from truth if you go for either green or amber as the rarest eye color in the world.
However, If you look at the eye as a whole and not only the color given off by the iris, then violet eye color with little dispute is probably even rarer than green or amber eye colors.
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