At 907 Whitehead Street in Key West, visitors arrive to inspect Ernest Hemingway's desk, Spanish colonial architecture and personal history. Then a cat walks across the property with what appears to be a pair of mittens attached to its front legs, and the famous author temporarily loses the room.
The Hemingway Home and Museum is home to nearly 60 cats. Many are polydactyl, meaning they have more than the usual number of toes. They sleep on furniture, patrol the gardens and carry names borrowed from famous people. It is part literary museum, part unusually elegant cat republic.
The founding-cat story
The museum's account says a ship's captain gave Hemingway a white six-toed cat named Snow White. Some cats living on the grounds today are described as her descendants.
That story has become polished through repetition, and historical details around famous animals can be surprisingly slippery. What is well established is that polydactyl cats have lived at the property for decades, the population is carefully managed, and the cats became inseparable from the public identity of the house.
Their fame is not incidental. In 2012, a US federal appeals court held that the museum was an animal exhibitor subject to regulation under the Animal Welfare Act. The court noted that the cats were integral to the museum's commercial purpose and attracted visitors from beyond Florida. Few house cats have generated federal case law merely by remaining at home.
Why do they have extra toes?
A standard cat typically has five toes on each front paw and four on each rear paw. Polydactyl cats grow additional digits, most often on the inner side of the paw. The result can resemble a thumb, a mitten or an impressively broad snowshoe.
The word describes the visible trait, not a breed. It can appear in mixed-breed cats and established breeds such as the Maine Coon.
Research on feline polydactyly found mutations in a regulatory region called the ZRS. This region helps control where the Sonic Hedgehog signalling gene is switched on while limbs develop. The name sounds like a rejected cartoon, but Sonic Hedgehog is a real and extremely important developmental signal.
The mutation does not add a new toe gene. It changes the instructions governing where an existing developmental system becomes active. A very small change in regulation can therefore produce a visible change in anatomy.
Why the paws do not all look alike
Even cats carrying related mutations can show different numbers and arrangements of digits. Some have extra toes only on the front feet. Some have them on all four. Some paws look broad and mitten-like; others simply appear to have added a small toe beside the standard set.
This variable expression is one reason the Hemingway cats became scientifically interesting. A 2008 study included cats from the Hemingway population and identified a shared point mutation associated with their polydactyly. The work helped researchers understand how tiny changes in a distant regulatory element can alter developing limbs.
Were extra toes useful on ships?
Polydactyl cats are often called ship's cats. Stories claim their broad paws improved balance at sea, made them superior climbers or turned them into gifted mousers.
These are excellent stories and weakly demonstrated biological claims.
Port communities could plausibly preserve a conspicuous inherited trait through founder effects and human preference. Sailors may also have valued unusual cats as lucky. None of that proves an extra-toed cat is automatically better at staying upright during a storm.
The responsible version is less cinematic but more interesting: human travel, local breeding populations, superstition and a heritable trait may all have helped polydactyl cats become unusually common in some coastal regions.
Do the extra toes cause problems?
Many cats with common forms of preaxial polydactyly live ordinary, healthy lives. Extra claws still need attention. A claw that does not contact the ground may not wear down normally, and cramped or oddly angled digits can be easier to overlook during routine checks.
Polydactyly is also a broad description rather than one single condition. Rare limb abnormalities can involve more than harmless extra digits. If a cat has pain, altered movement, inflamed skin, repeated claw injuries or a limb that appears structurally unusual, that belongs with a veterinarian rather than a charming historical narrative.
The cats became part of the house
The enduring appeal of the Hemingway cats is not really that a writer once liked unusual paws. It is that an inherited quirk became attached to a place, then outlived the people who first told the story.
The cats are living continuity. They turn a preserved house into something that still has routines, territories, births, names, arguments and favourite chairs. Visitors come looking for literary history and meet genetics walking through the garden.
Hemingway wrote that every man's life ends the same way. The cats have taken a more practical approach. They kept the house and added toes.
Sources & Further Reading
- The Ernest Hemingway Home and Museum: Our Cats.
- Lettice et al. Point mutations in a distant sonic hedgehog cis-regulator generate preaxial polydactyly. Human Molecular Genetics, 2008.
- Genetic heterogeneity of polydactyly in Maine Coon cats.
- 907 Whitehead Street, Inc. v. Secretary of the US Department of Agriculture, 2012.
- Wikimedia Commons image and licence record.
