Sturm R.A. & Larsson M., Genetics of human iris colour and patterns, Pigment Cell Melanoma Res, 22:544-562, 2009. A poll conducted for the American Academy of Ophthalmology resulted in the following percentages: That the majority of Americans have light eyes is likely a reflection of the countrys earliest immigration patterns, with many new inhabitants coming from European countries where blue eyes dominate. Viking stereotypes for being tall, strong, blond and blue-eyed are confirmed at least for the last two matters in the case of Denmark. Blue light may also damage your retinas. Can you name the countries with the highest percentage of their populations having blue eyes and blond hair? Only 2% of the world's population have green eyes, making it the rarest eye color. Both parents may have icy blue eyes, but that's no guarantee their child's eyes will even be blue at all. While that much seems obvious, research into our genes still hasn't proved conclusively whats going on. Brown eyes have the highest amount of melanin in the iris, and blue eyes have the least. For years, researchers had searched for it on the OCA2 gene. Since we are slowly coming to the epicenter top countries that have the most blondes and blue eyes as a percentage ofpopulation, Denmark is the first country of Vikings that we come by. Less melanin, the eyes are blue. They lower your risk of developing cataracts, for instance. Such albinos have pink eyes, as do albino rabbits, mice, or any other animal with a total lack of melanin. Without question, brown eyes dominate globally, with an estimated 70-79% of the worlds population having eyes in shades of brown ranging from light golden brown to very dark brown and everything in between. Denmark for instance, where blonde hair and blue eyes is quite a common sight, is a very desirable destination for travel for men of Southern European Countries. By Steve Asbell on 15 Jan 2019. Instead, the copper accumulates in the liver and in other tissues, including the iris of the eye. For example, the film actor Lee Van Cleef was born with one blue eye and one green eye, a trait that reportedly was common in his family, suggesting that it was a genetic trait. Image credit: Aleksandar Mijatovic via Shutterstock. [3]:9. Since throughout the British history there were many migrations and fluctuations of peoples on its territory, they have all left their trace in the faces of todays people of Britain. Blue eyes as a risk factor for type 1 diabetes. Iris color and associated pathological ocular complications: a review of epidemiologic studies. [4][34] Hazel eyes often appear to shift in color from a brown to a green. A common cause in females with heterochromia is X-inactivation, which can result in a number of heterochromatic traits, such as calico cats. Even people with the lightest blue eyes, with no melanin on the front of the iris at all, have dark brown coloration on the back of it, to prevent light from scattering around inside the eye. About half of people living in the U.S. and a higher population in Africa, and Asia are brown-eyed. . Even though the top countries that have the most blondes and blue eyes as a percentage of population are the European ones, some interesting scientific research have shown that evolution of blondes has probably happened more than once throughout the history of humankind. Blue-eyed humans have a single, common ancestor. Time for Heating Systems 101. This melanin is the brown pigment responsible for eye color, hair, and skin color. For the shade of purple, see, "Brown eyes" redirects here. [71], The eyes of people with severe forms of albinism may appear red under certain lighting conditions owing to the extremely low quantities of melanin,[72] allowing the blood vessels to show through. That same study suggested an intriguing possibility: Blue-eyed northern Europeans may have somehow adapted an ability to fend off seasonal affective disorder (S.A.D., also known as the winter blues). [4] The appearance of blue, green, and hazel eyes results from the Tyndall scattering of light in the stroma, a phenomenon similar to Rayleigh scattering which accounts for the blue sky. Brown eyes result from a relatively high concentration of melanin in the stroma of the iris, which causes light of both shorter and longer wavelengths to be absorbed.[27]. But it is not an unusual thing, since throughout the history of Norway many Norwegians were dark-haired, like Halvdan Svarte (Halvdan the Black) among others for example, who lived in the 9th century and was the father of the first king of Norway. All About Vision and AllAboutVision.com are registered trademarks of AAV Media, LLC. Dissection reveals that the iris pigment epithelium is brownish black due to the presence of melanin. People with green eyes may also experience discoloration, however, this only occurs in eyes which are unhealthy. Moreover, a gray iris may indicate uveitis, while those with blue, green, or gray eyes are at an increased risk of uveal melanoma. 9. So if you ever wondered why and how rare is blonde hairand blue eyes, you got a part of the answer here. That doesn't necessarily mean that the parents themselves have to have blue eyes; it's possible they carry the gene, but it is recessive. In Britain, for example, a 2014 study found that green was more prevalent than brown 30 percent to 22 percent although most were blue, 48 percent. The lack of pigment leads to red or violet eyes and often problems with their eyesight. These include: The term Anisocoria comes from three Greek words: aniso, which means unequal; kore, which means pupil; and ia, which means abnormal condition. Blue eyes are caused by a gene mutation. Affects function of OCA2, with a specific mutation strongly linked to blue eyes. Even though amber is similar to gold, some people have russet or copper colored amber eyes that are mistaken for hazel, though hazel tends to be duller and contains green with red/gold flecks, as mentioned above. Light or medium-pigmented brown eyes can also be commonly found in South Europe, among the Americas, and parts of Central Asia, West Asia and South Asia. Genetic research suggests that until about 10,000 years ago, pretty much everyone had brown eyes. The total number of genes that contribute to eye color is unknown, but there are a few likely candidates. People with blue eyes have a single, common ancestor, according to new research. Blue eyes are most common in northern and eastern Europe, particularly around the Baltic Sea. Plus, although this cancer is extremely rare, light-eyed folks are also more susceptible to sun damage from exposure to UV rays. Amber eye color is commonly found in Pakistan and the Balkan region, as well as in Southern France, the Iberian Peninsula, Italy, and Hungary, and in fewer numbers in the Middle East, Colombia, and the Southern Cone region. Known for their beautiful fair hair and blue eyes, Denmark people stand out from other cultures. Can You Have One Blue Eye and One Brown Eye? In severe forms of albinism, there is no pigment on the back of the iris, and light from inside the eye can pass through the iris to the front. In humans, the pigmentation of the iris varies from light brown to black, depending on the concentration of melanin in the iris pigment epithelium (located on the back of the iris), the melanin content within the iris stroma (located at the front of the iris), and the cellular density of the stroma. Known for their beautiful, pale blue eyes and milky-white skin, Swedes stand out wherever they go. Iris color depends on the protein melanin which is stored in special cells, melanocytes. Researchers found that only 17 to 22 percent of white cats with non-blue eyes are born deaf. "[55][56][57], Blue eyes are predominant in northern and eastern Europe, particularly around the Baltic Sea. Icelandic people demonstrate a strong national pride in preserving their culture. Verywell Health's content is for informational and educational purposes only. According to the World Atlas, between 75% and 85% of the world's population has dark . In fact, Hamilton should be proud to be part of an exclusive club: recent studies found that only one in six Americans now have blue eyes, down from roughly 50 percent at the beginning of the 20th . Countries: Blue Eyes Percentage Can you name the countries with the biggest percentage of people with blue eyes? It's completely normal to see blue become brown, hazel, or even green as they get a little older. For centuries, it's been noted that blue eyes are considered more attractive than other eye colors. The origin of the gene giving rise to blond hair color has been traced back to the last Ice Age 11,000 years ago. Cylindrical cells are the photoreceptors of the eye that have a black and white vision and, depending on the amount of light received from the environment, determine the amount of darkness and brightness of objects. Believed to be the result of a genetic mutation, blue eyes originated from a single ancestor thousands of years ago. 2012;36(2):234-240. doi:10.1007/s00266-011-9793-x, Di Stasio E, Maggi D, Berardesca E, et al. [18] Other genes implicated in eye color variation are SLC24A4[19] and TYR. This can make the blue eyes look slightly different depending on the type of lighting conditions. Redheads have fewer strands of hair on their heads. Because blue eyes contain less melanin than most other eye colors, they may be more at risk of certain damage. Redheads can change temperature quicker. Just 22 per cent now have brown eyes, while 30 . As the child develops, melanocytes (cells found within the iris of human eyes, as well as skin and hair follicles) slowly begin to produce melanin. If you see a dark outline around your iris -- the colored part of your eye -- this is your limbal ring. Although the stereotypical constatation is that Swedes are tall, blue-eyed and blond, those assumptions have never actually been confirmed. The polymorphisms may be in an OCA2 regulatory sequence, where they may influence the expression of the gene product, which in turn affects pigmentation. One more usual hair color is red, and also green eye color, being among the rarest in the world. [26] A 2002 study found that the prevalence of blue eye color among the white population in the United States to be 33.8% for those born from 1936 through 1951, compared with 57.4% for those born from 1899 through 1905. Normal eye colors range from the darkest shades of brown to the lightest tints of blue. [26] Hazel eyes are more common in Spaniards, North Africa, the Middle East, and Brazil. Norway. Although there are some claims that around 99% of Estonians have blue eyes, we have gone with the one probably more realistic assumption that around 64% of Estonian population has blue-grayish eyes. Norway. In their study, Eiberg and his team recruited 800 blue-eyed men and women across different countries. Green eyes are common in Europe's Central, Western, and Northern regions. Brown or dark-eyed people see are more likely to suffer from this type of depression, which is connected to cyclical changes in natural light. 2023 Dotdash Media, Inc. All rights reserved, Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. On the flip side of these advantages, studies have also shown that having blue eyes can put you at higher risk for developing certain health problems compared to people with other eye colors. 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