If you’ve spent much time with cats or have cats of your own, then you’ve likely noticed that there are a handful of very prevalent eye colors in cats. Amber, hazel, and blue are some of the most common eye colors in cats, but even in cats with less common eye colors, you’ve likely noticed an unusual trend—most cats don’t have brown eyes.
Some people mistakenly believe that no cats have brown eyes, and while there are cats with brown eyes, this eye color is exceptionally rare in felines. For being such a common eye color in other species, like humans and dogs, what would cause it to be rare in cats?
The 2 Reasons Most Cats Don’t Have Brown Eyes
1. Melanin
The iris of the eye, or the colored area surrounding the black pupil in the middle, is a multi-layered area of tissues that are packed with melanocytes. Melanocytes are responsible for melanin production. Melanin can impact things like skin and hair or fur color, so in the irises, the amount of melanin present in two of the layers of the iris is responsible for the color of the eyes. The two iris layers that are responsible for the color of a cat’s eye are the stroma and the posterior pigmented epithelium.
The more melanocytes in the irises, the more melanin is being produced, which will result in a darker eye color, and the fewer the melanocytes, the lighter the eyes will be.
The only exception to this is blue eyes. Blue eyes are actually completely absent of melanin in the thickest layer of the iris, the stroma. The blue coloration comes from light refraction on the iris.
In general, cats’ eyes don’t contain enough melanocytes to result in brown eye color, with the exception of the very few cats with true brown eyes.
2. Breed
There are certain eye colors that are part of the breed standard for multiple cat breeds. In some instances, all cats of a specific breed will have the same color eyes, while others may have multiple eye colors within the breed. There are no cat breeds that have dark brown eyes as part of the breed standard. There are, however, multiple breeds that variations of brown are common or necessary for the standard.
The lighter variations of brown eyes are common in breeds like the Bombay, Sphynx, British Shorthair, American Shorthair, Manx, Bengal, Scottish Fold, and Abyssinian. The darkest eye color you’ll see in most cats is copper, which is a brown color with undertones of reds and oranges.
Are Eye and Coat Color Related?
It may make sense to think that cats with dark coats are more likely to have dark eyes and cats with light coats are more likely to have light eyes, but this actually isn’t true.
In humans, the genes that control eye and hair color are close to each other within the chromosome, and because of this, it’s not uncommon for hair and eye color pairings to occur. This is why blue eyes aren’t uncommon in people with blonde hair, but they are very rare in people with black hair. In cats, these genes are not related to each other.
The only exception to this is, once again, with cats that have blue eyes, as these cats are more likely to be light in color, which is related to the dominance of the white coat gene. White cats with blue eyes (one or both) are at higher risk of being deaf (in one or both ears) than white cats with green or yellow eyes. Blue eyes aside, your cat could have essentially any combination of coat and eye color. This means that you can have both a dark and light coat colored cat with any eye color.
Unusual Eye Color Combinations
Believe it or not, not all cats have two eyes that match. Dichromatic and heterochromia are both uncommon, with dichromatic being very rare, but both of these conditions indicate that a cat’s eyes contain two different colors.
Heterochromia refers to the eyes each being different colors. This can result in a wide variety of color combinations, and shades of brown, copper, and hazel can be combined with the opposite eye sporting a completely different color, like green or blue.
Dichromatic refers to each eye containing two colors. This means that the eyes likely match each other color-wise, but both eyes are a combination of two colors. This typically appears as one color surrounding the irises and another color surrounding the first color, but it is also possible for the colors to show up in streaks and splashes.
Conclusion
Brown eyes are very uncommon in cats, and when they do occur, they almost always appear in a lighter shade like copper. This is due to the number of melanocytes that appear in most cats’ eyes, resulting in lower melanin production than you might see in species that commonly have brown eyes, like dogs and humans.
You might luck into spotting a cat with darker brown eyes, and if you do, you should count your lucky stars because you’ve seen a very rare cat indeed!
Featured Image Credit: Mary Swift, Shutterstock
