Breeding
Humankind has been dabbling in the science of heredity, or genetics, in both the canine and equine world for centuries to encourage specific physical traits for practical purposes: dogs for guarding herd animals or the homestead; horses for speed or for pulling heavy loads. But the small build of felines excluded them from anything beyond mousing. So when breeders turned their attention to the cat, it was for aesthetic, not practical, reasons.
The cat fancy movement (groups dedicated to the selective breeding, proper care and showing of cats) started up in the late 1800s. At this time, the great majority of the feline population, the ubiquitous mixed-breed household cat, was the result of natural selection. But what could the early breeders work with? To spice up the mix, enter the variety of "natural," or historic, types occupying geographically isolated pockets of the world. Cats used for crossbreeding — Turkish Angora, Persian, Siamese, British shorthair, Russian blue and Abyssinian — had achieved distinctiveness without human intervention hundreds, in some cases thousands, of years ago (although some have since been refined by modern breeders).
The vast majority of breeds are hybrids, created by crossing already established breeds with each other. For instance, the popular exotic combines the sturdy build and broad face of the Persian with the more manageable coat of the American shorthair and other shorthair breeds. The other way that new breed characteristics sprout is through haphazard mutations. These genetic changes result in traits such as taillessness or stub tails, abnormally short legs, bent or curled ears, curly hair or even hairlessness. While some mutations are crippling or deadly and others merely controversial, some are desirable, and these traits were deliberately isolated and bred for repetition by cat breeders. Some feline mutations, such as the taillessness of the Manx from the Isle of Mann and the shortened appendage of the Japanese bobtail, flourished without human intervention, but within the vacuum of geographic isolation.
