why can't you have eye colors other than: shades of Green, Blue, and Brown?

Question

like no one has red eys,etc.

Answer 1

Actually, if you have ever seen an albino person, their eyes are mainly white with a redish tint in the pupil,

Answer 2

this phenomenon is genetical. ris color can provide a large amount of information about an individual, and a classification of various colors may be useful in documenting pathological changes or determining how a person may respond to various ocular pharmaceuticals. Various classification systems have ranged from a basic "light" or "dark" description to detailed gradings employing photographic standards for comparison. Others have attempted to set objective standards of color comparison.
As the perception of color is dependent on viewing conditions (e.g. the amount and type of illumination, as well as the hue of the surrounding environment), so is the perception of eye color.

Eye color exists on a continuum from the darkest shades of brown to the lightest shades of blue.Seeing the need for a standardized classification system that was simple, yet detailed enough for research purposes, Seddon et. al developed a graded one based on the predominant iris color (brown, light brown, green, gray, and blue) and the amount of brown or yellow pigment present. There are 3 true colors in the eyes that determine the outward appearance; brown, yellow, and gray. How much of each color you have determines the appearance of the eye color. The color the eyes in turn depends on how much of these colors are present. For example, green eyes have yellow and some brown, making them appear green. Blue eyes have a little yellow and little to no brown, making them appear blue. Gray eyes appear gray because they have a little yellow and no brown in them. Brown eyes appear brown because most of the eye contains the brown color. Brown is the most common, blue is second, and green is rarest. The above is true for the species Homo sapiens. The iris color can vary in the animal world. Instead of blue in humans, autosomal recessive color in the species Corucia zebrata is black. whereas, the autosomal dominant color is yellow - green ( Subspecies comparison of the Genus: Corucia - Leeway Corucia Research Center - LCRC, Polyphemos, {2006}).

Answer 3

Red/pink eyes appear only with Albinism where there is a lack of pigment in the iris so the light reflected off the retinal blood colors it. For this there are actually several known genes that allow several levels of lowered ocular pigmentation and differing amounts of red showing through the iris.
http://ghr.nlm.nih.gov/condition=ocularalbinism

Melanin exists in two forms in human eyes, skin, and hair: eumelanin, which is a brown-black color and the pigment it is made from, phomelanin, which is a yellow-red color. The relative ratio controls hair/skin color. If a lot of melanin is present, the eye will appear brown or even black. If little melanin is present, the iris appears blue. Intermediate amounts of melanin produce gray, green, hazel, or various shades of brown. But these colors may be modified by one other pigment lipofuscin known to appear in aged or with illness in light pigmented eyes.
http://ezinearticles.com/?Changing-Your-Eye-Color---Iris-Color-Facts&id=863980

The iris is colored by, its background skin, its stroma (those radial lines from pupil to white in the iris), and the number of stroma. Pigments localize in the iris's stroma more than the background skin.
Eye color genes are called
EYCL1, green/blue eye color.
EYCL2 that colors the iris center darker.
EYCL3 brown/blue

Dominance order
EYCL3 brown >EYCL1 green >EYCL3 blue = EYCL1 blue

The brown version of EYCL3 appears in the stroma, the blue version does not, either exist in the background skin of the iris. This is how the rich dark colors appear in brown eyes while blue eyes can appear almost glass clear with so little pigment until the very back of the iris.
Other genes may be the source of flecks, rays, rings, and diffusion patterns.
Genes for the pigment lipofuscin (lipochrome) in the iris that may determine grey, hazel, amber, green, and violet eye colors have yet to be found.
MC1R is the gene to switch between phomelanin & eumelanin pigment expression. If you inherit one of the dozen recessive alleles you will carry the gene for red hair, light skin and light colored eyes.
http://www.madsci.org/posts/archives/2001-06/993598918.Ge.r.html
http://ghr.nlm.nih.gov/gene=mc1r


Eye color variants appeared in northern European ancestors when skin pigmentation was lowered to acquire more vitamin D from sunlight with an increased angle of incidence in northern latitudes.
http://pages.globetrotter.net/peter_frost61z/European-hair-and-eye-color.htm
Even the Neanderthal had red hair with MC1R alleles
http://news.bbc.co.uk/1/hi/sci/tech/7062415.stm

Answer 4

coz the genes responsible for eye colour are capable to synthesize the pigments only in these range of colours.so the eye colour can be in the range of blue,brown,black or green.in majority of asians, eye colour is black.
interesting question by the way.

Answer 5

there's also gray, hazel and black, but i see what you mean. It's just like hair colors are shades of blonde,brown,red and black. I guess that's why they invented flourescent hair dye and designer contacts (which can come in red )

Answer 6

that's probably because none of our ancestors have red eyes. eye colour is a gene that is inherited, usually from parents but sometimes from grandparents and extended relatives.

Answer 7

conjunctivities dude!! red eye!

Answer 8

u dont wanna look like demon, fish or just plain zombified

Answer 9

Because any other color would freak people out. . .*cough*red=demon*cough*