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| Hazel Eyes |
Hazel
Hazel iris (Inner brown and outer green ring)Hazel eyes are due to a combination of Rayleigh scattering and a moderate amount of melanin in the iris's anterior border layer. Hazel eyes often appear to shift in color from a light brown to a golden-green. Hazel mostly consists of brown and green. The dominant color in the eye can either be green or light brown/gold. This is how many people mistake hazel eyes to be amber and vice versa. This can sometimes produce a multicolored iris, i.e., an eye that is light brown/amber near the pupil and charcoal or dark green on the outer part of the iris (and vice versa) when observed in sunlight. . Hazel eyes are common in the following countries and regions such as Romania, Czech Republic, Austria, France, Spain, Bulgaria, Greece, England, Portugal, Chile, Italy, Hungary, Eastern Germany, Serbia, Croatia, Slovenia, United States, West Asia, Eastern Russia, Estonia, Mexico, Jordan, Israel, India, Afghanistan, Argentina, Brazil, Colombia and Montenegro.
Definitions of the eye color hazel vary: it is sometimes considered to be synonymous with light brown or gold, as in the color of a hazelnut shell.
From Wikipedia , the free encyclopedia
What are Hazel Eyes?
The definition of hazel eyes varies. For some, hazel eyes range from a light brown to a medium golden-green. In North America, "hazel" is a term used to describe eyes that appear to change color, ranging from light brown to green and even gray, depending on lighting in the environment.
Characteristics of Hazel Eyes
A large percentage of hazel eyes have a brown ring around the iris, and either green or blue coloring around the outside of the ring. In the image to the right, you can see the darker inner ring surrounded by a lighter outer ring. To learn more about the subject, read about how genetics affect eye color
Read more:
http://www.brighthub.com/science/genetics/articles/16272.aspx#ixzz18UWiF0CSThe Genetics Behind Hazel Eyes
The genetics of hazel eyes is not clear yet and has received little research attention. There are only models that try to explain it. One model is explained by Dr. Barry Starr, from Stanford University. However, it is only a model and many others may surface soon.
According to Dr. Starr, a new gene (yet to be found) could be a modifier gene of the gey gene. This gene, named M could produce hazel eyes by having the gey make more melanin. As with any gene, the M gene comes with two alleles, the M which increases the amount of melanin gey makes and the m which has no effect.
Studying the possible combinations of the G (gey) and the M (modifier) genes it would be possible to explain (theoretically) hazel eyes. Anytime you get the G with the M gene you will get hazel eyes (according to this model). So, if a person has the following combinations: GGMM, GbMM, GGMm, and GbMm he (or she) will have hazel eyes. If the person has GGmm and Gbmm he will have green eyes and if he (or she) has bbMM, bbMm, or bbmm he or she will have blue eyes.
Hazel eye color genetics will of course become clearer one day, but for the moment it's models such as Starr's that give us the best insights.
Genetics is also responsible for human characteristics such as blue eyes, blonde hair, and red hair.
Read more:
http://www.brighthub.com/science/genetics/articles/16272.aspx#ixzz18UX2kg00Sources
Genetic determinants of hair, eye and skin pigmentation in Europeans. By Patrick Sulem et al. Nature Genetics 39, 1443 - 1452 (01 Dec 2007)
Dr Barry Starr (
http://www.thetech.org/genetics/ask.php?id=126).
