Like the Scottish Fold, the American Curl’s defining characteristic is its unique ears. In the Curl’s case, the ears curl backward in a smooth arc. Show quality Curls must have a curl arc that is at least 90 degrees and no more than 180 degrees. The moderately large ears must be erect and must have firm cartilage from the ear base to at least one-third of the height. The ears are set equally on top and to the side of the head. The shape is wide at the base and open, and the ear tips are rounded and flexible. Furnishings are desirable. Adult Curls are disqualified if the tips of the ears touch the back of the ear or head, or if their ears are severely mismatched, thick, or have inflexible tips.
The curled ears are expressive; they perk up in curiosity, swivel to listen, and twitch back in annoyance. They can’t lie flat, however, because of the firmer cartilage.
American Curls are well-balanced cats, semi-foreign in type, flexible and moderately muscled, and slender rather than massive in build. Boning is medium, neither fine nor heavy. They are small to medium in size—adult males weigh approximately 7 to 10 pounds; adult females weigh about 5 to 8 pounds. Proportion and balance are more important than size. The tail is flexible, wide at the base but tapering at the end; its length is equal to the body’s length. Legs are medium length and in proportion to the body with medium boning, neither fine nor heavy.
American Curls come in both long and shorthair varieties. Longhairs have fine, semi-long, silky coats that lie flat, with minimal undercoats. The tail hair is full and plumed. Shorthairs have short, soft, silky coats that lie flat and are resilient without being plush or dense. They also have minimal undercoats. For both hair lengths, all colors and patterns are accepted, including the pointed pattern.
In June of 1981, two stray cats with unusual curled ears arrived on the doorstep of Grace and Joe Ruga in Lakewood, California. One suffered an unfortunate accident soon after arriving, but the other, a longhaired black female, was adopted by the Rugas. They named her Shulamith, a variation of a Hebrew term that means "black but comely." At first, they paid little attention to their cat’s unique ears; they assumed other curly-eared cats existed somewhere, even though they could find no mention of them in books at the local libraries and pet stores. They were more impressed with Shulamith's deep devotion and loving personality. In December of 1981, however, Shulamith gave birth, and two of the four kittens also had curled ears.
Although the Rugas didn’t know much about genetics at the time, this indicated that the gene governing the trait was dominant, since the father, a local longhaired tom named Mr. Grey, did not have curly ears or the gene for them. Because the curl gene is dominant, only one parent needs to have the gene to produce or sire Curl kittens, which is a big advantage for a breeding program. Unlike a recessive gene, a dominant gene will always be expressed in the cat's physical appearance. If a cat doesn't have curled ears, she doesn't have the curl gene. A spontaneous genetic mutation in the domestic cat population was very likely responsible for the unique ears.
Shulamith continued to have litters with the local toms, adding to the local Curl population. The Rugas gave away kittens to friends and family, including Grace's sister, Esther Brimlow. Both long and short hair appeared in early litters, and many colors and patterns, including pointed.
Esther Brimlow gave two Curls to former Australian Shepherd breeder Nancy Kiester, who showed her Curls to cat judge and Scottish Fold breeder Jean Grimm. Grimm told Kiester Curls were unknown to the cat fancy. Nancy Kiester teamed up with Grace and Joe Ruga, named the breed the American Curl, and, with Jean Grimm's help, wrote the first breed standard. Both hair lengths and all patterns and colors were included. They also made the very good decision not to include pedigreed breeds as outcrosses; this could have created resistance from other breeders in the cat fancy.
They exhibited the first American Curl at the October 1983 CFA show in Palm Springs, California. Cat fanciers immediately recognized that the Curl's unparalleled ears were unique and acceptance quickly followed. In 1986, TICA granted the Curl championship; in 1993, CFA followed suite. In a comparatively short time, the American Curl gained recognition from all the North American cat associations, an achievement that generally takes new breeds decades longer. The breed's numbers are still relatively low, however. The Curl currently ranks 27th out of the 41 breeds CFA recognizes for championship.