The color of the eyes depends mainly on the amount and type of pigments present in the iris. People have many possible eye colors - depending on the classification, from 16 to even 80 variants. Find out who we inherit our eye color from, what the world statistics and eye color charts look like.
Eye color is closely related to melanin, a pigment also found in varying amounts in the skin and hair. Eye color inheritance is related to the eye color of ancestors, but not necessarily of the parents themselves. Find out what determines the color of the eyes, what color in people is predominant and what is the least, and whether the most famous violet eyes in the world, once owned by Elizabeth Taylor, are true or just a PR ploy.
Eye color - what does it depend on?
In humans, eye color depends on the pigment melanin (black pigment) and the varying proportions of eumelanin pigment (dark brown pigment) to pheomelanin (reddish pigment).
The brightly colored eyes of many bird species are largely determined by other pigments such as pteridines, purines, and carotenoids.
Apart from the pigments in the iris epithelium and the melanin content in the stroma of the iris, the eye color is determined by the concentration of the stroma of the iris. Iris color variants depend on the melanin content within the stroma of the iris, since each iris, regardless of eye color, contains this dye. In turn, the cell density of the iris stroma determines how much light is absorbed by the underlying pigment of the epithelium.
Do you know that…Melanin determines not only the color of the eyes, but also the color of the skin (complexion) and the ability to tan quickly or slowly, the color of the hair and the number of moles on the skin. The more melanin, the darker the shade. Brunettes and dark-eyed lockers have a lot of melanin, while blondes and redheads have much less of it. Apart from the aesthetic aspect, melanin has another very important function - it absorbs ultraviolet radiation. Albinos are therefore not immune to this radiation due to the deficit of melanin.
Eye color - inheritance
The color of the iris is inherited from the ancestors, but not necessarily from the parents. Several genes influence eye color. Their combinations create different shades or difficult onesto clearly define the colors.
Although the color of the eyes obviously depends on the set of genes we receive from our parents. However, their color may change, which we witness after the birth of a child. For the first moments of life, the toddler has light blue eyes, after a few months stronger pigments are released and the color may change to brown or green.
The simplified eye color inheritance theory we learn in school says that when the dominant gene takes over, we tend to have dark eyes and blue when recessive. On the other hand, if the father has a recessive and dominant gene, there is a 50% chance that the offspring will have dark or light eyes. When both parents have blue eyes, their child will have no beer. Such a pair has two recessive genes each, so they cannot pass on dominant genes to the child.
What does the expert say?Krystyna Spodar, MD, PhD, specialist in the field of clinical genetics at NZOZ Genomed in Warsaw (www.nzoz.genomed.pl):"In fact, eye color is determined by the amount of melanin (black pigment) and the ratio of eumelanin (dark brown pigment) to pheomelanin (reddish pigment) The OCA2 and HERC2 genes play the most important role in determining the color of the irises, but apart from these, there are at least 10 other genes known to influence this trait. Ultimately, all these genes work together to determine the final effect. So blue-eyed parents can have brown-eyed children. "
Read on: What determines the color of a child's eyes?Eye color - genes
Eye color is an inherited trait influenced by more than one gene. There are two major genes and other minor genes that account for the enormous number of possible eye color combinations. In humans, three specific regions of the chromosome occupied by genes related to eye color are known: EYCL1, EYCL2 and EYCL3. These genes are responsible for the three phenotypic eye colors (brown, green and blue). All three genes need to specify the same color in order for the eye color to be clear. Otherwise, we will get a mixed color, e.g. beer (brown + green) or gray (blue + green).
All babies are born with blue eyes. Eye color usually stabilizes around six months of age.
In 2006, the molecular basis of the EYCL3 locus was analyzed. After examining a group of 3,839 people, the researchers found that 74% of all eye color variations can be explained by single nucleotide polymorphisms (SNPs) close to the OCA2 gene, which, if mutated, can cause a type of albinism. Recent studies have shown that SNPhave a strong relationship with blue and green eyes as well as the number of freckles, moles, hair and skin tone.
Why doesn't frequent sun exposure change my eye color?Melanin in the eye does not undergo the same changes as melanin in the skin. So if we sunbathe often, we have no chance of changing the color of the eyes from lighter (blue) to darker (hazel or dark brown). This is because the eye's defense mechanisms would prevent the inflow of such a large amount of ultraviolet radiation into the iris (the simplest mechanism is to close your eyes in strong sunlight).
Besides, by focusing the sun's rays, the cornea would not be able to illuminate the entire iris. This would risk damaging the photosensitive eye structures and losing its ability to function properly.
Eye color - tables
Just as color perception is affected by the factors in the presence of which color is seen (e.g., intensity and type of lighting, as well as ambient tint), so is eye color perception.
Eye color varies from the darkest shades of brown to the lightest blue. Seeing the need to standardize a classification system that is simple yet detailed enough for research, anthropologists developed a gradual system based on the predominant color of the iris (brown, light brown, green, gray and blue) and the content of a brown or yellow pigment.
Do you know that…It is assumed that people with a given dominant eye color live in specific geographic regions of the world. For example, Asians have very dark eyes, while typical Slavs have blue or gray eyes. Sometimes it is difficult to tell what eye color someone is.
Sometimes it is difficult to tell what eye color someone has - it changes slightly with the lighting. There are also eyes with different colors - this condition is called heterochromia (see below).
There is also a system based on three basic colors: brown, yellow and gray, and their proportions determine the color of the eye. For example, light brown eyes have a lot of yellow and some brown pigment, blue eyes have very little yellow pigment and no brown pigment at all, green eyes are blue eyes with quite a lot of yellow pigment. Gray eyes are gray because they have little yellow and faint amounts of brown pigment. Brown eyes appear brown because most of the eye contains brown pigment.
Classification taking into account different spots and areola on the iris, which makes it extremely detailed, is the scale of prof. I. Michalski based on the Martin scale. It contains as many as 80possible eye color variants.
Brown eye color is the most common (90%), blue is second (7%), the proportions between gray and green are similar, but most often it is assumed that 2% of the population is gray and green is the rarest (1%).
One of the most famous classifications of eye colors is the Martin scale.
Martin's anthropometric eye color scale: 1. Dark eyes:
- 1 - black-brown (dark brown)
- 2, 3 - dark brown (dark brown)
- 4 - brown (hazel)
2. Transitional or mixed eyes:The mixture of pigments takes the form of a more or less even distribution of pigments in the iris (mainly in the form of spots) or a pale iris surrounded by a thick brown rim. With lighter shades with a small admixture of brown pigment in the form of small spots or a narrow rim around the pupil.a) eyes mixed with a predominance of darker shades:
- 5, 6 - light brown (light brown), known in English asamber eyes
- 7 - green-hazel, in English:hazel eyes
b) mixed eyes with a predominance of lighter shades:
- 8 - light green (or green-blue)
- 9, 10 - dark gray (with a touch of green)
- 11 - gray
3. Light eyes:
- 12 - light gray
- 13 - ice blue
- 14, 15 - blue
- 16 - light blue (light blue)
Eye color - different colored irises
One of the birth defects is heterochromia, which is the uneven color of the iris or both eyes. This is an extremely rare defect that affects approximately 1% of the population. It consists in a different position of the dye on at least two parts of the iris of one eye and a different color of the eyes.
A person suffering from this disorder may have one eye brown and the other blue, or a filet ring on the beer iris. Heterochromia is not bothersome and does not cause a vision defect, and is not always a genetic defect. Actresses Jane Seymour, Mila Kunis, Kate Bosworth and the actor Kiefer Sutherland have different colored irises. David Bowie also had different colors of iris colors.
There are two types of heterochromia:
- heterochromia iridis - variegation of one iris
- heterochromia iridium - when both irises have a different color
Find out more: HETEROCHROMIA, or the different colored irises of the eye
See why some people have two-colored eyes
Eye color - violet eyes - is it possible?
Violeteye color is associated with the American actress Elizabeth Taylor. Violet visible in the eyes is most often the result of mixing red and blue reflections. In fact, people with violet eyes may have blue irises that, under the influence of lights, blood vessels, or appropriate makeup, may just look like violet.
One scientific explanation also implies the link between purple eyes and albinism. Albinos are born with no pigment in the skin, skin, hair, and iris of the eye. The lack of pigmentation makes their eyes appear purple-blue or red.
About the author
Katarzyna TerentiewManaging editor of Wformie24.pl. A graduate of Polish Studies at the University of Warsaw. As an editor, she co-created many entertainment TV programs, in the literary monthly "Bluszcz" and the biweekly "Viva!" she was the editorial secretary. Mother of two full of energy children. He has been spending his holidays sailing for many years.
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