COLOR OF EYE

===Blue===
Blue eyes contain low amounts of melanin within the iris stroma; longer wavelengths of light tend to be absorbed by the underlying iris pigment epithelium, and shorter wavelengths are reflected and undergo [[Rayleigh scattering]].<ref name="Wang"/> The type of melanin present is eumelanin.<ref name=Menon>{{cite journal |author=Menon IA, Basu PK, Persad S, Avaria M, Felix CC, Kalyanaraman B |title=Is there any difference in the photobiological properties of melanins isolated from human blue and brown eyes? |journal=Br J Ophthalmol |volume=71 |issue=7 |pages=549–52 |year=1987 |month=July |pmid=2820463 |pmc=1041224 |url=http://bjo.bmj.com/cgi/pmidlookup?view=long&pmid=2820463 |doi=10.1136/bjo.71.7.549}}</ref> The inheritance pattern followed by blue eyes is considered similar to that of a [[recessive]] trait, however it's a [[polygenic trait]] (meaning that it's controlled by the interactions of several genes, not just one).<ref name=Grant/> Eiberg and colleagues showed in a study published in ''Human Genetics'' that a mutation in the 86th [[intron]] of the [[HERC2]] gene, which is hypothesized to interact with the [[OCA2]] gene [[promoter]], reduced expression of OCA2 with subsequent reduction in melanin production.<ref name="blue mutation">{{cite journal |author=Eiberg H, Troelsen J, Nielsen M, ''et al.'' |title=Blue eye color in humans may be caused by a perfectly associated founder mutation in a regulatory element located within the HERC2 gene inhibiting OCA2 expression |journal=Hum. Genet. |volume=123 |issue=2 |pages=177–87 |year=2008 |month=March |pmid=*******0 |doi=10.1007/s*******07-0460-x |url=http://www.springerlink.com/content/2045q6234h66p744/fulltext.html}}</ref> The authors concluded that the mutation may have arisen in a single individual in the [[Near East]] or around the [[Black Sea]] region 6,000-10,000 years ago during the [[neolithic revolution]],<ref>Jeanna Bryner, "Genetic mutation makes those brown eyes blue: Scientists find that blue-eyed individuals have a single, common ancestor: How did actress Reese Witherspoon get those big blue eyes? A team of scientists has found that blue eyes are linked to a genetic mutation that occurred between 6,000 and 10,000 years ago," M**, January 31, 2008, found at [http://www.msnbc.m**.com/id/*******4/wid/*******3?GT1=10815#storyContinued Lay summary from M**.com].
===Brown===
Brown eyes are predominant in humans<ref>{{cite journal |author=Eiberg H, Mohr J |title=Assignment of genes coding for brown eye colour (BEY2) and brown hair colour (HCL3) on chromosome 15q |journal=Eur. J. Hum. Genet. |volume=4 |issue=4 |pages=237–41 |year=1996 |pmid=8875191 }}</ref> and, in many parts of the world it is nearly the only iris color present.<ref>{{OMIM|227220|SKIN/HAIR/EYE PIGMENTATION, VARIATION IN, 1; SHEP1}}</ref> It is less common in countries around the [[Baltic Sea]] and in [[Scandinavia]]. Dark pigment of brown eyes are most common and with a few exceptions the only color among the population of [[East Asia]]. In humans brown eyes contain large amounts of melanin within the iris stroma, which serves to absorb light at both shorter and longer wavelengths. Brown eyes are the most common eye color, with over half of the world's population having them .
===Gray===
Gray eyes have less melanin than blue eyes,{{Fact|date=January 2009}} even though they are considered a darker shade of blue (like blue-green). Gray eyes are most common in European [[Russia]], [[Finland]] and the [[Baltic States]].{{Fact|date=December 2008}} Under magnification, gray eyes exhibit small amounts of yellow and brown color in the iris. Ultimately there are at least two things that could determine gray eye color. The first is the amount of melanin made and the second is the density of the proteins in the stroma. <ref>{{cite web |url=http://www.thetech.org/genetics/ask.php?id=232 |title=Are gray eyes the same as blue in terms of genetics? |work=Understanding Genetics: Human Health and the Genome |publisher=Stanford School of Medicine |author=Lucy Southworth}}</ref>
===Green===
Green eyes are the product of low to moderate amounts of melanin and probably represent the interaction of multiple variants within the [[OCA2]] and in other genes, including perhaps the red-hair gene.<ref>[http://discovermagazine.com/2007/mar/eye-color-explained Eye Color Explained <!-- Bot generated title --> ]</ref> They are most common in [[Northern Europe]] and [[Central Europe]] <ref>[http://www.eyedoctorguide.com/eye_general/eye_color.html Blue Eyes Versus Brown Eyes: A Primer on Eye Color - EyeDoctorGuide.com <!-- Bot generated title --> ]</ref><ref>[http://cogweb.ucla.edu/ep/Frost_06.html Why Do Europeans Have So Many Hair and Eye Colors?]</ref>.
===Hazel==
Hazel eyes are due to a combination of [[Rayleigh scattering]] and a more than moderate amount of melanin in the iris' anterior border layer.<ref name=Wang/><ref name=Lefohn>{{cite journal |author=Lefohn A, Budge B, Shirley P, Caruso R, Reinhard E |title=An Ocularist's Approach to Human Iris Synthesis |journal=IEEE Comput. Graph. Appl. |volume=23 |issue=6 |pages=70–5 |month=November |year=2003 |doi=10.1109/MCG.2003.1242384 }}</ref> Hazel eyes often appear to shift in color from a light brown to a medium golden-dark green. A number of studies using three-point scales have assigned ''hazel'' to be the medium-color between the lightest shade of blue and darkest shade of brown. Hazel mostly consists of Brown and Green. The dominant color in the eye can either be green or brown.