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What Makes Black Cats Black?

Are they just tabbies in disguise? Why do they sometimes “rust?” Get your geek on with me as I explore the science behind my favorite felines.

 |  Oct 31st 2013  |   75 Contributions


It’s no secret that I love black cats. I’ve railed against the injustice of anti-black cat prejudice and pondered why people still believe the ridiculous myth that black cats are bad luck. I’ve shared my stories of black cat love and encouraged people to share theirs. But the one thing I’ve never done before is talk about the science of black cats. That changes today. Check out these seven facts surrounding genetics and other science facts of ebony kitties and their giant-size cousins.

My cat, Bella, sprawled on the bed and basking in a sun puddle. You can see that she has a reddish undertone in certain light.

1. In order for a cat to be solid black, both of its parents need to have the black color gene

The color gene -- called an allele -- for black is known as B. It is dominant to other variations of the gene, known as b and b’, which produce chocolate and cinnamon colors. Keep in mind, though, the ultimately dominant cat fur color pattern is tabby. So for a cat to be solid black, it must also carry a recessive gene known as a non-agouti (a), so that the tabby pattern doesn't appear. Cats who have the dominant agouti gene will retain the tabby pattern. Which brings us to our next point.

2. Some black cats are tabbies in disguise

If a cat has the black allele but the expression of the tabby gene isn’t completely repressed, you might be able to see ghostly tabby stripes on your black cat. In these cats, you might see tabby stripes on the tail or legs, or the classic “M” pattern on the head, if she’s sitting in the bright sunlight.

In this photo of Sinéad, you can see the very faint tabby "M" on her head.

3. Black cats’ fur can fade or “rust”

Heavy exposure to sun can cause a black cat’s fur to change to a rusty brownish color. Another reason your cat might look rusty in normal lighting conditions is a deficiency in an enzyme called tyrosine. Tyrosine is required for the creation of eumelanin, the pigment that makes your cat’s fur black. If your black cat is rusty, talk to your vet about this possibility and whether it would be safe to give your cat a tyrosine supplement to see if she blackens up again.

4. Black cats can go gray as they age

Like humans, all cats sprout white hairs as they age, but it’s more obvious in black cats. This is a natural phenomenon and nothing to be worried about. Some cats start going gray earlier than others, but it’s very unlikely that your cat will go completely gray.

Samuel L. Catson has plenty of white hairs mixed in with the black fur on his head and shoulders. He's only about 8 or 9, according to vets, but he had a hard life on the streets before he was transported north to HART of Maine, where he will have a safe home for as long as he needs it.

5. The big cat we call a panther is actually two different cats

Panthers in the Americas are melanistic (black-coated) jaguars, while panthers in Africa are melanistic leopards. If you look at either of these cats, you’ll see shadows of the usual markings -- spots on a jaguar and rosettes on a leopard.

6. African and American panthers have different black genes

In jaguars, the black coloration is a dominant gene, meaning that only one copy of the allele is needed to express that color. However, in leopards, black coloration is a recessive gene, so a leopard would need to have two copies of that allele to be black.

A melanistic jaguar (or what we in the Americas call a panther) at the Henry Doorly Zoo in Omaha, Nebraska, (CC-BY-SA) by C. Burnett

7. Black coloration might boost cats’ immune systems

Research by the National Institutes of Health is showing that genetic mutations found in black cats seem to make them more resistant to illnesses such as feline immunodeficiency virus, or FIV. The work is nowhere near complete, but the agency's work with black domestic cats and jaguars does show some promise -- not just for FIV treatment but for HIV treatment, too.

Do you know of other cool scientific facts about black cats? How about some legends about black cats as icons of good luck? Please share them in the comments.

A melanistic leopard (also known, in Africa, as a panther) at the Rhino & Lion Nature Reserve, Kromdraai, South Africa, (CC-BY-SA) by Gary Whyte

About JaneA Kelley: Punk-rock cat mom, science nerd, animal shelter volunteer, professional cat sitter, and all-around geek with a passion for bad puns, intelligent conversation, and role-play adventure games. She gratefully and gracefully accepts her status as chief cat slave for her family of feline bloggers, who have been writing their award-winning cat advice blog, Paws and Effect, since 2003.

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