Why do humans have different colored eyes?
408653
Most babies have blue eyes when they are born and then their eyes darken as they age.\n\nWhen someone has two eyes of a different color it is pretty rare and usually results from some sort of genetic loss of pigmentation or can result from eye trauma.\n\nThe basis of eye color mostly has to do with melanin pigmentation.  If you have a lot of melanin you have brown eyes if you have very little you have blue eyes.  Everyone else is somewhere in between except people with green eyes which can result from flecks of yellowish fatty pigments against a dark background.
1160277
Theoretically, the answer is no; all people do not see the same shade and intensity of color.  Color vision occurs as a result of specialized photo-receptors in our eye.  The number of these receptors can differ from person to person, and as a result, some people may be more sensitive to certain colors than others.  A simple way to test this would be to take freshly isolated retinas from various individuals (ie: laboratory animals) such that the photoreceptors (rods and cones) are still intact and expose the retinas to lights of different wavelengths (ie: colors) and intensities while simultaneously recording the neuronal output generated in response to the lights.  I haven't done such an experiment myself, but it is very logical to assume that no two individuals would respond the same way to the lights, since perception of the light stimulus depends on the frequency and duration of the activation of the receptor neuron as well as the number of receptor neurons activated and their distribution in the retina.
1033380
there might be other creatures that we are not capable of seeing, some call them ghosts, or demons or spirits. We are limited the 5 senses to sense the world around us.\nWe know dogs can hear different frequencies that us, they also have different senses, some say they can see ghosts or other invisible things to us. \nImagine if all human didn't have eyes and could not see, we would have no consept of color, we would not know the difference between day or night. same thing now, if we had "other" senses we could've seen or sensed new and different things that currently we have no understanding to it.\n\nI think the ghosts interact with us and we sense them but we usually think it is our gut feelings.
12543
From a physics/physiology standpoint, we have color because light waves come in different lengths and our eyes perceive a limited band of thoses lengths with differing responses by light sensors in the eyes.\n\nFrom an evolutionary standpoint, color vision (as opposed to black and white), gives us a great deal more information to process our environment.  For instance, a brightly colored bird might hardly be visible to an animal with only black and white vision, but we see it easily, even against a confusing background.  Color can help us see the difference between animal (browns) and plants (greens), healthy(a child covered in mud) and unhealthy (a child covered in blood), and other differences that are more easily recognized due to the greater information richness available.
327803
my friends used to say my eyes were orange, but they are just light brown as well.  Maybe we are unique and have a new eye colour?
76619
The answer lies in the structure of the eye.  There are two types of receptors in the eye, rods and cones.  Cones are the color receptors but are less sensitive to light.  Rods are very sensitive to light but do not distinguish color.\n\nMany animals, especially nocturnal animals, pack a greater number of rod receptors into their eyes allowing them greater sensitivity to light allowing them to see in conditions that are too dark for huuman eyes with their lesser number of rods.\n\nIt is a tradeoff between color and light sensitivity with humans weighing in more heavily in the color category.
227705
Yes, the colour of the eyes can change by using contact lenses. I don't know if it can change by a physical way.
1091523
Melanin pigment found in human skin, iris, hair comes in many shades: \n\nyellow-gold-green-brown-dark brown-almost black is from weakest to strongest shades\n\nThus humans have HUGE variation in their skin shades, the eye colors and their hair colors (even without the use of artificial hair dyes, contact lenses or tanning tonics-tanning booths)\n\nThe darker races you mention USUALLY have the heaviest distribution of the darker shades of melanin than others, but once there is mixing of these gene pools with lighter skinned humans, all sorts of things can happen, including the various shades of green eyes and lighter skin.  Some scientists believe that skin shade is transmitted by polygenetic genetics, so numerous genes are involved. Most texts still explain eye color as simple complete dominance genetics, but I believe we are not to the bottom of this issue yet and that it is much more complex than this...i.e. that there are more factors involved than one gene. The hair color thing is at the very LEAST dihybrid genetics, esp when you start adding the red to the melanin.  Red pigment is different than the melanin and when mixed with all the different shades of melanin can give a whole slough of different color combinations in hair.  It is possible to find many people of those darker melanin "races" to have lighter eyes, hair or skin, but it is just rarer due to the gene pools.  As the percent of interracial mixing increases and the number of caucasians continues to decrease all over the planet, the percent of humans with the darker melanin will increase and the lighter blondes, blue-green eyes will decrease.  It is happening fast as we look at the spots on the earth where the population is exploding the most.....all the darker  pigmented humans \n\nRacism in humans has been around since the dawn of time.  All ethnic groups have their "time" on the earth when they are more or less accepted or more or less rejected and subjected to prejudice than during other eras.  Law of Karma keeps dishing out the "same ole, same ole"......same with prejudice against a cultural group......cultures come to the TOP and cultures drop to the bottom....just like businesses......there is a nature cyle in life....all things will have their hayday and all things will have their time of demise. Look at history.  Not much new really happens in history.  Fashion and hairstyles may change, but the human games and stories don't really change much! Duality-polarities of life exist as a part of natural law and is how karma operates! You know...."the dark and light sides of the force." Ignorance breeds ignorance, hate breeds hate, love breeds love, tolerance breeds tolerance, compassion breeds compassion. You're either ready, willing or able to be tolerant or you aren't! Tough lessons for many on this planet still even though human history is filled with horrific records (potential lessons! You'd think we could learn and make some progress!) of the human atrocities lower consciousness humans inflict upon other humans. Some have to learn thru pain, though.  Some can learn from watching the pain and suffering of others. Some love to inflict pain no matter what, are just more animal like in their "struggle for survival" in a "dog eat dog" world. It is amazing to me that even with all the genocide in human history on various sides of the earth that we humans would get a clue! "Father, forgiove them, for they know not what they do!"
571803
My eyes change color as well. I have hazel eyes.  But they go to a solid green or blue.  They also get an orange or brown color to them as well.  As to why, I dont know.  But most people whose eye color changes have hazel eyes.
836323
of course, the person concerned doesn't require to be a european to have colored eyes. i'm an indian' and several of the people here i know have blue/green eyes.
103659
I like blue eyes because I was born with them but that changed as I grew up to more of a dull green.  It is pretty rare to see people with blue eyes so it seems to be a pretty unique property.  Since I wear contacts, I have considered wearing blue ones just to get back what I used to have.   I do think that it depends on the person because there are some people who I think would be better with blue and some people who I think would look better with brown eyes, it really depends.
1037519
Good question!\n\nNature has evolved molecules that pigment various parts of organisms.  Plants and flowers are the obvious case in point, but in humans, skin pigments, and those in the iris (giving us blue, green brown etc. eyes) have also evolved.\n\nIt is QUITE POSSIBLE that at some point in the past, alternative pigmentation DID evolve in humans, and the only thing we CAN say with any certainty, is that if it did, if was later eradicated from the gene pool, and does not ersist any longer.\n\nMost notably, the only ANIMALS that have evolved the colours you mention have been birds, where the ability to fly away rather than the need to camoflage and blend in is the preferred means of evading redators.  So bright colours in these cases are NOT dangerous to the organism (bird) displaying them.\n\nIt is true that some other apes (primates) DO display bright colours.  Some have bright red backsides, and in some cases, bright blue pigment is evident on parts of the bodies.\n\nSo as a final thought:  in a world where bright colouring is no longer likely to be life endangering to humans, how long will it be before a random genetic mutation causes pigmentation other than the standard tan and browns that we are used to to evolve?!
17833
To elaborate on the previous response: Color is merely your brain's interpretation of light (electromagnetic radiation in the visible spectrum) entering your eye. A difference in color corresponds to a difference in the light's wavelength. And just as there are an infinity of numbers between 0 and 1 (fractions), you could also technically say there are an infinite number of colors between the shortest wavelength of visible light and the longest. This is the answer you'd get from a physicist.\n\nBut, a physiologist/neurologist might have a different answer. As I stated, color is an interpretation of the chemical reaction between light and the rods and cones in the back of your eye. The fact that it's an interpretation and the fact that we can't detect very small differences in wavelength suggests that there is a much smaller set of colors that we, as humans, could define given our very limited built-in equipment (our eyes). Even among humans it varies though, I have no idea what my girlfriend is talking about sometimes. It's not for lack of trying, my eyes/brain (as with many guys) is capable of detecting a smaller set of colors than girls. Is her set more valid than mine?\n \nAnd I'm sure an artist and a poet would tell you something completely different :)
982980
In the eye there r rods N cones. rods allow us to see details while cones colours! cats n dogs have more rods than human beings.
1170811
If you are meaning the color of a person's eye, it is the iris that has the color that others see. If you mean someone having two different colors of eye, that is called heterochromia.
76027
Hair color, eye color, and also skin color are determined by special proteins called pigments.  The pigments in your hair, eyes, and skin are encoded in your genes, which is was these traits are said to be genetic.  All molecules absorb some wavelengths of light and reflect others.  Pigments are typically complex molecules that reflect certain wavelengths in the visible spectrum and absorb others.  Different people have different color pigments because there are minor changes in the DNA sequences that code for the pigments which result in minor changes in the molecules themselves, which in turn change the wavelenghts of light that are reflected and absorbed.  If someone has blue eyes, it is because the pigments in their eyes reflect a lot of wavelenghts of blue light, and absorb most other colors.
606213
Having one's eyes not the same colour is known as heterochromia, and is usually the result of damage to one or other eye.\n----\nThe Q & A below is the best reference I could find:\nQuestion:\nI have Heterochromia iridis (different colored eyes, where one eye is of two colors), and I was wondering if there are statistics on how many other people have this trait? My particular case is independent of disease or disorder, but I was curious. \n \nAnswer:\nWe were unable to find a specific number for the frequency of heterochromia of the iris in the general population. Asymmetry in the pigmentation of the irides probably occurs as an isolated phenomenon inherited as a dominant trait. This means a parent with heterochromia of the iris has a 50/50 chance to pass the trait to their offspring.