The American Curl is the cat breed with a distinctive curled-back ear caused by a natural mutation first documented in California.
The breed began with a stray black female cat named Shulamith, who appeared at a California home in 1981. Her unusual ears curved backward instead of standing upright in the usual feline shape. When Shulamith had kittens, some inherited the same feature, demonstrating that the trait was genetic.
Breeders developed the American Curl from these cats, while outcrossing with domestic cats helped maintain genetic diversity. Kittens are born with straight ears; the ears begin curling within days and reach their mature shape after several months.
The American Curl is often confused with the Scottish Fold. Scottish Folds fold forward and downward because of a different cartilage mutation, whereas American Curls sweep backward. The breed can have either short or long hair.