Cats purr in many situations: a mother nursing her kittens, being petted or fed, visiting the vet, or recovering from an injury. Cats purr when they are happy, even while they eat. But a cat can also purr when it is hurt, hungry or nervous, so a purr does not always mean a happy cat.

For about half a century, scientists thought a purr needed the muscles of the voice box to tighten and relax in a steady rhythm. The brain, they thought, gave constant orders. A 2003 Scientific American answer said cats make the purr through on-and-off signals to the laryngeal and diaphragmatic muscles. It said a purr runs through both breathing in and breathing out at 25 to 150 hertz.

Many cats flip themselves rightside-up in the air. They bend at the waist and twist the front half of the body one way and the back half the other way. A cat's spine has about 30 vertebrae, so it is very flexible and can rotate half of its spine 180 degrees. Cats also have no collar bone, and their shoulder blades lie along the sides of the body, so they can slip through narrow spaces.

A cat's claws pull back into a sheath held by an elastic part of the toe. This keeps the claws from getting blunt. A cat's whiskers have a scientific name, vibrissae, which comes from a Latin word meaning to vibrate.

Kittens are born with their eyes closed, and the eyes open when they are about 7 to 10 days old. A cat's pupils are long and vertical, narrowing to a slit in bright light and opening wide when it is dark.

Cats are crepuscular, which means they are most active at dawn and dusk rather than being truly nocturnal. Unlike other meat-eating mammals, cats depend almost completely on prey they have killed themselves. Play is hunting practice. A playing cat may stalk a toy, crouch and grab it.

The cat family, Felidae, includes lions, tigers, jaguars and cougars. The house cat is the only member that has been domesticated. Big cats such as lions, tigers, leopards and jaguars have a partly bony hyoid and a flexible larynx that let them roar.

The oldest known cat burial is in Cyprus, where a person and a cat were buried together 9,500 years ago. Cat bones have also been found in 5,300-year-old trash pits in China.

The domestic cat's DNA traces back to a wildcat called Felis silvestris lybica, which lives in North Africa and the Near East. Researchers have long said cats were first domesticated by early farmers in the Near East about 10,000 years ago, as of November 2026. The farmers welcomed wildcats because the cats kept their stored cereal grain free of vermin.

Words to know

• purr: soft cat hum
• vertebrae: backbone pieces
• crepuscular: active at dusk
• domesticated: tamed over generations
• vibrissae: whiskers