Eye color

Eye color or eye colour (see spelling differences) is a polygenic trait and is determined by the amount and type of pigments present in the eye's irisWielgus AR, Sarna T. "Melanin in human irides of different color and age of donors." Pigment Cell Res. 2005 Dec;18(6):454-64. PMID 16280011.Prota G, Hu DN, Vincensi MR, McCormick SA, Napolitano A. "Characterization of melanins in human irides and cultured uveal melanocytes from eyes of different colors." Exp Eye Res. 1998 Sep;67(3):293-9. PMID 9778410.. Although there seem to be three genotypic eye colors (brown, green, and blue), humans and other animals have many phenotypic variations in eye colorMorris, PJ. "Phenotypes and Genotypes for human eye colors." Athro Limited website. Retrieved May 10, 2006.. These variations in color are attributed to varying ratios of eumelanin and pheomelanin melanocytes in the iris.

Colors

Brown eyes

The vast majority of the world's people have dark eyes, ranging from brown to nearly black. Light brown eyes are also present in many people, but to a lesser extent. Most of the original inhabitants of Africa, Asia, and the Americas have brown eyes. Brown eyes are also found in Europe, Oceania and North America, though within European populations they are not predominant to the same extent. Brown had been considered to be the most dominant eye color in any gene, but new studies have revealed that this is not always true. Very dark brown irises are, and may often seem black in color.

Black eyes

Black eyes are a very dark shade of brown. The exact color of the human eye is determined by the amount of a single pigment called melanin that is present in the iris of the eye. Melanin is a dark brown pigment that is deposited on the front surface of the iris. If a lot of melanin is present, the eye will appear very dark brown.

Hazel eyes

Hazel is usually used to describe eyes that contain elements of both green eyes and brown eyes, sometimes transitioning from green at the edges to brown around the pupil. This should not be confused with irises that display a brown, yellow, or copper-colored ring around the pupil, as in the amber iris shown below. Hazel eyes are also known as light brown eyes. They are dominant in middle European countries such as the middle of Russia, Belarus, Ukraine, south and middle of Poland, south and middle of Germany, north of France, Switzerland, north of Italy, Slovenia and others.

Blue eyes

Among human phenotypes, blue eyes are a relatively rare eye color. They are found mainly in people of northern European and eastern European descent, and to a lesser extent, in people of southern Europe, the Middle East and Central Asia, most commonly in people who live at higher elevations. South Asians may also have blue eyes, but this is uncommon, except amongst Pathans and Parsis and people in Pakistan, and also in India. For example, blue eyes are most common in Punjab and Kashmir,with fewer numbers in Gujarat and Rajasthan. Finland and Lithuania have the highest percentages of blue-eyed people, with at least 80% in both countries respectively. Ireland and Great Britain also have high percentages of blue eyes, with estimates for being around 70% for Ireland and about 65% for Britain. Many Caucasian babies are born with blue eyes, though their eyes will darken, or change color. Most infants' eye color will set within a couple of days to a couple of weeks, though some people's will continue to change for a number of years.

Blue is the color of the indole monomer that when polymerised forms melanin. If both alleles for brown eyes (a polymerase gene) are absent or damaged, the blue color remains. Hence blue eye color is a recessive trait.

In the mid-20th century after the dawn of color films, blue eyes were considered very desirable in those aspiring to be Hollywood actors and actresses although this became less true during the latter half of the century.

A 2002 study found the prevalence of blue eye color among non-Hispanic whites in the United States to be 57.4% for those born between 1899 and 1905 compared to 33.8% for those born between 1936 and 1951Grant MD, Lauderdale DS. "Cohort effects in a genetically determined trait: eye colour among US whites." Ann Hum Biol. 2002 Nov-Dec;29(6):657-66. PMID 12573082..

Gray eyes

Gray eyes are a (often lighter) variant of blue eyes. A wide variety of shades of grey exist, from the almost white (light grey) to dark.

The underlying gray color may be tinted with various other colors, as in the greenish-gray eyes in the picture. "Steel blue" eyes are also found, ranging from a slightly desaturated blue to light blue-gray.

A yellow-, amber- or copper-colored ring is commonly seen around the pupil. This is a normal part of the iris, and should not be confused with Kayser-Fleischer rings. As with other colors, gray eyes are often seen to change color depending on the surrounding colors.

Green eyes

Green eyes are rarer than brown, hazel, blue and gray eyes. Green eyes are most often found in people of Celtic, Germanic, and Slavic descent. Hungarians have the highest percentage of green eyes of any population, close to 20%. Green eyes are also found, though in far lower proportions, among other Caucasian populations in the Middle East and South Asia. They are so common among Pashtuns that in Pakistan, Pashtuns are often called "Hare Ankheian Vaale": people with all different eyes.. They may also be found in many areas of northern India, especially in Punjab and Kashmir.

One of the most famous photographs ever published by National Geographic was a close-up of Sharbat Gula, a Pashtun girl with startling green eyes, taken in western Afghanistan by Steve McCurry in 1984. Details of her irises captured by the photograph were used to confirm her identity after she was relocated in 2002.

Blue-Green eyes

Blue-green eyes are relatively uncommon and usually consist of an iris with a predominantly blue color, usually darker blue, with green streaks or stippling caused by a yellow- or copper-colored overlay. Yellow-, amber-, or copper-colored rings are often present around the pupil.

The exact color is often perceived to vary according to its surroundings. Wearing lighter blue colors or getting tanned tends to emphasize the blue components. Wearing bright red, green, and shades of yellow or brown can emphasize green components, or even give the impression of gray.

Blue-green eyes are considered a blue variant.

Violet Eyes

Violet eyes are extremely rare and are a variation of blue eyes. They are believed to be caused by eyes having so little pigmentation that the red and blue blood vessels permeate through, causing a violet color of the iris. A noteworthy subject is Elizabeth Taylor, whose physical trademark is her violet eyes.

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