National Black Cat Day Is a Campaign That Worked

A black domestic cat is a tabby with the pattern switched off. The stripes are still there in its genes, and in many black kittens they show through as faint "ghost" tabby markings that sink into the dark background as the cat grows up. What switches them off is one small mutation: two letters of DNA missing from one gene.

That cat is the subject of October 27th, a day with a better record than most. Its founder set out to change one number, and kept publishing the number.

A Charity Started It, and Said Why

National Black Cat Day was created by Cats Protection, a UK cat welfare charity, and launched on October 27, 2011. It ran that first year as Black Cat Awareness Day and took its current name in the campaign's second year.

The reason was a figure from the charity's own rehoming centers. Black and black-and-white cats in its care were taking, on average, about seven days longer to find a home than cats of other colors. The campaign was built to close that gap, with photographs of black cats, public appeals, and a yearly date to hang them on.

The US keeps a separate observance, Black Cat Appreciation Day, in August. The two get merged on social media every year. They have different dates and different histories, and only the October one comes with a set of rehoming figures attached.

The Gap Closed

By 2019, according to Cats Protection, black cats were waiting two more days on average than cats of other colors, down from about a week. A 2020 update from the charity reported that black cats were spending ten fewer days in its care before rehoming than they had a decade earlier, and that the length of stay for black and black-and-white cats had fallen by 21% over the previous five years. Its centers have found homes for more than 65,000 black and black-and-white cats since 2011.

Those are a charity's figures about its own centers, published by the organization running the campaign, so they describe one network of shelters and say nothing about the UK as a whole. They are still a rare thing for an awareness day to have: a baseline, a goal, and a follow-up.

The superstition side is less tidy. A Cats Protection survey in 2015 found that 12% of respondents aged 18 to 24 thought black cats were unlucky, against 2% of those over 55. Whatever slows black cats down, it is not confined to older people with older beliefs.

The Photograph Problem

One study points at something more ordinary. Miranda Workman and Christy Hoffman of Canisius College followed 892 cats listed on the adoption site Petfinder by a shelter in western New York, from October 2012 to October 2013, and published the results in 2015. Cats with black or smoke coats received significantly fewer clicks per day and stayed available for adoption longer than cats of other colors.

The study did not test why. The obvious candidate is the camera, since black fur swallows detail in a dim kennel shot and leaves the eyes as the only readable feature. The study's most useful finding concerned the one thing a photographer controls: pictures that included toys drew more clicks. A cat batting at a wand toy shows an adopter the play drive behind one of the five pillars of a healthy feline environment, and it does so in a frame where the cat is moving and easy to see.

Two Letters Missing

The genetics were worked out in 2003. Eduardo Eizirik and colleagues at the National Cancer Institute's Laboratory of Genomic Diversity published "Molecular genetics and evolution of melanism in the cat family" in Current Biology. Black coloration in domestic cats, they found, comes from a 2 base pair deletion in ASIP, the agouti signaling protein gene. Agouti is what bands each hair with lighter pigment. Without a working copy, the hair stays dark from root to tip.

The same paper looked at wild cats and found a messier picture. Black jaguars carry a deletion in a different gene altogether, MC1R, and black jaguarundis carry a different deletion in that same gene. Melanistic animals from five other species carried none of these mutations, which put the minimum at four separate origins of black coats in the cat family. At the time, melanism was known as a common variant in 11 of the 37 cat species.

A 2012 follow-up by Alexsandra Schneider, Eizirik and colleagues, "How the leopard hides its spots", found that the black leopard uses the domestic cat's gene with a mutation of its own: a single-letter change in ASIP that is predicted to shut the protein down entirely. The Asian golden cat has yet another ASIP change. So "black cat" covers at least two genes and several unrelated mutations, each arrived at independently.

Why Black Skips Generations

The gene decides how the coat is inherited. Melanism from MC1R is dominant, so one copy is enough, and a favorable black coat can spread through a population quickly. Melanism from a broken ASIP is recessive in every species where it has been studied. A black house cat carries two copies of the deletion, one from each parent, and two non-black parents that each carry a single copy will produce black kittens about a quarter of the time.

Black is a coat color with no breed attached, so the deletion turns up in pedigree cats and in the domestic shorthair, the mixed-breed cat behind most of the world's pet cats. It changes the fur and nothing else about the animal wearing it. A black cat in a rehoming pen asks for attention with the same tool every other cat uses on people, a meow that adult cats barely use on each other. The ghost stripes on its kitten coat are the giveaway: the tabby was there all along, hidden by two missing letters of DNA.

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