All about black cats
A black cat is a stunning creature, a sinuous being made of inky velvet, which glimmers in just the right light.
A black cat is also long misunderstood, accused, through the ages, of bringing bad luck or good, knowing witches or acting on behalf of the devil, causing ships to sink, or having the power to prevent illness.
Today, even though we know better, black cats are still a source of wonder and mystery. We’re still learning from them and about them. Today, there’s even a scientific connection between the genes that make cat fur black and human HIV infections. Fascinating!
Let’s find out what we know about black cats today.
What is a black cat?
Black cats have black fur, black nose leather, and black toe beans, because the genes that determine the pigment of a cat’s fur also determine the color of these other body parts.
In fact, if you have a jet-black cat with any other color nose leather, you should wonder why. It is likely be due to an illness or disease.
Vitiligo, for example, is a disease that destroys a cat’s pigment producing cells (melanocytes), causing the affected skin to turn white or pink. Likewise, solar dermatitis, a skin disease caused by overexposure to sun, can cause the formation of white or pale patches of skin, including on the nose.
In other words, a black cat is usually just black. In cat fancy, the term for a solid-black cat is “self black.”
The only part of the black cat that isn’t black: the eyes
There’s not been a lot of research into cat eye color, in general, except for blue eyes. Blue eyes are linked to Siamese cats, and also to the gene that causes white patches to form in bi-color cats, or causes cats to be completely white. You can read about these in my posts on white cats and tuxedo cats.
In some pedigreed cats, eye color is determined by the breed standard, which can vary from registry to registry. In those cases, breeders select for the “preferred” eye color, so it can appear as though certain fur colors are genetically associated with certain eye colors, even though they are probably not.
Some breeders of black cats prefer to select for dramatic orange or coppery eyes. But black cats can also have green or yellow eyes. There is nothing in their genetics that requires black cats to have eyes of a certain color.
(Interested in learning more about cats’ eyes? Read, “Can cats see in the dark?”)
What cat breeds come in black?
Each cat registry may have its own rules, but the Cat Fanciers’ Association (CFA) recognizes 22 different breeds that may be registered with black fur, including one (the Bombay), that must have black fur. These include:
- American Bobtail
- American Curl
- American Shorthair
- American Wirehair
- British Shorthair
- Cornish Rex
- Devon Rex
- Japanese Bobtail
- Maine Coon
- Norwegian Forest Cat
- Oriental Shorthair
- Scottish Fold
- Selkirk Rex
- Turkish Angora
But most of our black cats are not pedigreed. They’re just beautiful domestic long- or short-haired cats who happen to have jet fur.
How do cats get their black fur?
This is almost impossible to believe, but cats only come in two colors: orange and black.
I know you’re going to tell me I’m crazy, because you have a gray cat at home, or a white cat, or a lovely little tabby. But, genetically speaking, underneath that gray, white, or striped fur, all of those cats are orange or black.
There are other genes that “do something” to whatever black or orange genes a cat has. They might make the colors look softer. They might let stripes show. They might cover up the black or orange altogether. But underneath a cat’s fancy colors, the black and orange genes are there.
Coat color is a sex-linked trait in cats
If you remember your high-school biology, you might know that we (and cats) have little packages of genes inside every one of our cells. These packages of genes are called chromosomes, and they determine a lot of things about us, like the size of our feet, or the color of our hair. Chromosomes come in sets of two, and we get one from each of our parents.
Everyone, including cats, has one special pair of chromosomes that decide if we’re going to be male or female. For a girl to be a girl she has to get two “X” chromosomes, described as XX. For a boy to be a boy, he has to get an “X” and a “Y” chromosome, described as XY.
Since mothers only have Xs, they give an X to their sons as well as their daughters. Fathers, who have both, can give an X or a Y. If dad gives an X, his child will be XX and female. If dad gives a Y, his child will be XY and male.
The astounding thing is that these sex chromosomes do more than determine whether a kitten will be a boy or a girl. In cats, coat color is also on the X chromosome. That’s why we call it a “sex-linked” trait.
It takes only one X to make a boy cat black
Because a boy only gets one X chromosome, he is whatever color that is on his X. If his X has a black gene, he’s black. If his X has an orange gene, he’s orange. So easy!
Of course, I’m putting aside all the other special genes that can act on his black or orange genes. But just for a moment.
It takes two Xs to make a girl cat black
It gets a little more complicated with the ladies, because girl cats have two Xs that decide coat color.
If a female cat has black genes on both of her Xs, she will be black. If a female cat has orange genes on both of her Xs, she will be orange. If she gets one of each, she will be calico.
So, having two color genes, instead of one, just makes it less likely that a female cat will turn out black.
Chances are, if you see a randomly bred black cat (not a pedigreed cat, in which the genetics have been controlled), it is more likely to be male.
It also explains why nearly all calico and tortoiseshell cats are female. You can read all about it in this post on calico and tortoiseshell cats. You can also read about orange cats in this post.
Black cats come in three colors
Black fur, in cats, isn’t always black. There are actually three versions of the black-fur gene.
There’s black, of course, but there are also variants of the black gene that reduce the amount of black pigment (eumelanin) that gets deposited on a hair. Less black pigment makes a cat appear brownish in color.
One variant of the black gene makes a chocolate-colored cat, while another variant of the black gene produces a cinnamon-colored cat. Even though black-, chocolate-, and cinnamon-colored cats look wildly different to us, they are actually the result of different versions of the very same gene.
But the chocolate and cinnamon versions are recessive to true black (and cinnamon is recessive to chocolate), meaning that it’s “easier” (genetically speaking) to be born black for a cat, than chocolate or cinnamon.
And black cats come in even more colors!
There are other genes that can alter how dense the color is that gets deposited on the fur. These genes are called “dilute modifiers” and they cause pigment to be deposited unevenly on a hair. Dilute modifiers kind of wash out the color, and give it a dusty appearance. It can be stunning.
If a cat gets even one “non-dilute” or "dense" version of the dilute-modifier gene, the color of her fur will be deep and very intense. Black will be jet black.
But if a black cat gets two dilute genes, he will be gray.
If a chocolate cat gets two dilute genes, she will be lilac, a pinkish-gray.
If a cinnamon cat gets two dilute genes, he will be fawn, a pinkish-beige.
And that’s just the beginning. Don’t get me started on shaded silvers, black smokes, or chinchillas!
Why is my black cat “rusting”?
There’s one black coat color in cats that isn’t really a color.
Have you ever seen a black cat that appears to be “rusting,” especially after time spent in the sun?
Eumelanin, the pigment that is required to produce black fur, is surprisingly fragile and can start to break down when exposed to sunlight. Deep, dark black can “rust” into a reddish-brown shade. This isn’t dangerous for the cat.
But there’s another, more troubling possible cause of rusting: an amino-acid deficiency.
Amino acids are the building blocks of protein, and one particular amino acid, tyrosine, is required to make eumelanin, the pigment that makes a black cat’s fur black.
A 2002 study published in the Journal of Nutrition showed that adding tyrosine to a cat’s diet reverses the reddishness in black fur.
Be sure to feed your cat a high quality commercial cat food, to ensure she’s getting all the micronutrients, and especially amino acids, she needs to be healthy.
What is Black Cat Syndrome?
You may have heard that black cats (and dogs) aren’t adopted as frequently as animals of other colors, and are euthanized in shelters more often. The name Black Cat Syndrome was given to describe this condition.
Whether Black Cat Syndrome really exists, however, is still up for debate.
Why might black cats be less adoptable?
Photography. Black cats are notoriously more difficult to photograph than cats of other colors, and in the online-adoption world of Petfinder, that’s a problem. Dark fur can hide facial features, making black cats appear less expressive than lighter-colored cats.
Superstitions. It’s hard to believe that in the 21st century, ideas held over from the Middle Ages, could be affecting cat adoptions today.
But black cats’ association with witches, the devil, or bad luck, could cause some potential adopters to overtly or subconsciously shy away from black cats.
A 2019 study evaluated this potential bias, by showing photographs of black cats to study participants. The study concluded that there is bias against cats with black fur, especially amongst people with greater superstitious beliefs.
Additionally, people in the study who had trouble reading the emotions of black cats in the pictures, tended to be more biased against them.
Black cats take longer to be adopted out in shelters
Some scientific studies do show that black cats take longer to get adopted in shelters.
One study of two shelters in Colorado showed that solid-black cats took an average of 26 days to be adopted versus around 20 days for non-black cats.
Six days doesn’t sound like a lot, but research shows that each additional day spent in a shelter can increase a cat’s risk of respiratory infections by 5%, and cause flare-ups of other stress-related diseases.
Other studies show that black cats are more likely to be euthanized in shelters, too.
Some studies debate the idea of Black Cat Syndrome
Dr. Emily Weiss of the ASPCA reviewed data from the organization’s A Comprehensive Animal Risk Database, which included information about 300,000 cats and dogs in 14 different communities.
She did find that euthanasia numbers were highest for black animals, but that adoption was also the highest of any colors, with 31% of cat adoptions being black cats.
Her conclusion was that there were just more black cats coming into the shelters than any other colors.
So, if three black cats and one white cat enter a shelter on a given day and one white cat and one black cat are adopted, it would still leave two black cats at the shelter. It would certainly appear, to someone visiting the shelter, that black cats aren’t getting adopted.
What should I do about Black Cat Syndrome?
Whether Black Cat Syndrome is a myth or not, does not negate the fact that there are more black pets in shelters than lighter-colored animals.
Next time you are looking to add a new kitty to your household, consciously check your own potential biases as you scroll through Petfinder, or walk through the shelter. Make a concerted effort to give the black cats a second look.
And, if the fit is right, consider giving a black cat a second chance at a home, too.
Black cats and the fight against HIV in humans
There are an awful lot of black cats out there. Some sources I consulted say that black is the most common color for cats, although I could not find any scientific research to back this claim up.
Black is actually a surprisingly common color for wild cat species, too. Of 36 species (aside from the domestic cat), 11 have a naturally occurring black-gene mutation, including the leopard, cheetah, jaguar, caracal, serval, jaguarundi, lynx, bobcat, Scottish wild cat, and Goeffroy’s cat.
But black is actually a weird color for a wild animal. Most wild animals have pelts that blend in to their surroundings. Researchers believe that there must be a reason so many cats have black fur. There must be something in black fur that confers some survival advantage on a black cat.
Interestingly, researchers have found that the gene that makes wild cats black is in the same family of genes that are involved in how people become infected with certain viruses, including HIV. Humans with mutations in the same gene that causes cats to be black, are less likely to become infected with HIV.
For humans, is there something that researchers can learn from black cats about how to prevent people from contracting HIV?
For cats, is it possible that black fur means that cats are better protected against the feline version of HIV (FIV) or other diseases? Is it possible that black fur actually helps cats survive? And could that explain why there are so many black cats?
(Read about feline immunodeficiency virus in this post.)
Famous black cats
India, also known as Willie. India, an all-black American Shorthair, lived in the White House with former President George W. Bush and First Lady Laura Bush.
Her name became a source of controversy when protesters in India claimed it was an insult to their country and burned an effigy of the president.
The cat, however, was named after a Texas Ranger baseball star, nicknamed “El Indio.” Bush had owned the team at the time the cat joined the family.
Blackie. Blackie was the world’s richest cat. His guardian, an antiques dealer, left most of his fortune to three cat charities. He bequeathed Blackie, the last of his 15 cats, a cool $12.5 million.
Oscar. Oscar is also known as the Bionic Cat. When his hind paws were severed in an accident, he was referred to an orthopedic surgeon who performed a groundbreaking surgery on him to implant prosthetic feet.
Celebrate your black cat
Every day with cats is a day to celebrate. But if you want to make it official, August 17 is National Black Cat Appreciation Day around the world. You can also celebrate National Black Cat Day on October 27 in the U.S.
Get your fill of black cats at the world’s only all-black-cat café
The world’s first and only all-black-cat café is located in Himeji, Japan. Here, the cats wear different-colored bandanas so guests can tell them apart.
Even if you can’t visit the café in person, you can visit Cat Café Nekobiyaka virtually here:
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Dawn LaFontaine is a lifelong animal lover who always seems to have a little pet hair in her keyboard. Her blog, Kitty Contemplations, helps cat guardians better understand and care for the special beings they share their lives and homes with. Her cat-products business, Cat in the Box, sells beautiful, well-made, and award-winning products that she designed to meet the biological needs of cats.
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Ed – I love that you adopted four!!! I have two black dogs myself, so that probably counts, too.
I have 4 black cats. 1 boy and 3 girls. No superstition here.