Of the more than 600 million cats worldwide, less than 10% belong to any particular breed. But are these purebred cats the result of human intervention, or are some naturally occurring?
The answer is more complicated than you might think. Most cat breeds have developed over the past 140 years as a result of human selection for specific physical characteristics, said Leslie A. Lyons, a cat geneticist at the University of Missouri School of Veterinary Medicine.
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According to Sarah Hartwell, a cat genetics enthusiast and founder of the cat resource MessyBeast, the ancestors of natural breeds are formed under the same conditions as wild breeds.
“Natural varieties can be thought of as a step on the road to speciation,” she told Live Science. Most often they are formed as a result of environmental adaptation. Cold, snowy conditions in western Russia favored thick-furred and big-boned cats, which formed the basis of the Siberian forest cat breed. In Southeast Asia and the Indian Ocean, the warm, humid environment suited cats with short hair, slender bodies, and large ears, and this was the setting for the birth of the Abyssinian cat.
In some cases, natural varieties may arise as a result of geographic isolation. This phenomenon, known as the founder effect, occurs when a population’s isolated gene pool is so small that genes that are not advantageous to the animal’s survival spread. On the Isle of Man (a British Crown dependency in the Irish Sea), a short-tailed mutation spread as a result of inbreeding, creating the ancestor of the Manx cat. Unfortunately, Manx cats can suffer from spinal defects due to this tail mutation.
Although the ancestors of natural breeds evolved under natural conditions, modern cats of these breeds are no longer so “natural”.
“Regardless of the species, all varieties have been influenced by humans,” Lyons told Live Science. According to a study published in the journal Animal Genetics that she co-authored, cat breeding has increased rapidly over the past century, removing the environmental pressures that created natural breeds.
For example, the Manx species likely went extinct naturally due to a lack of genetic diversity and the negative effects of the short-tail mutation. As a result of intentional breeding by humans, it is still widely used today. But some people try to eliminate it.
“The idea is to either retire this breed or find a way to make it healthier,” Lyons told LiveScience. “Maybe we [work toward] A Manx with a tail. ”
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Some varieties that once existed naturally are more closely related to their roots than others. For example, modern Siberian cats are genetically and physically similar to their ancestors because breeders regularly bring in new cats found as strays or pets in the breed’s homeland to add to their breeding programs.
Other breeds have been modified both genetically and physically from their original appearance. For example, Russian Blues were bred with Siamese cats after World War II to prevent the breed from becoming extinct, but breeders have since divided them into specific “types” that look different from the original cats.
Certainly, “natural” cat breeds exist, but they are not completely natural. The typical characteristics of a Maine Coon purchased from a breeder, such as large size, square jaw, and feet that often have six or more toes, may be similar to the Maine Coon discovered in the 1800s, but they have been preserved and, in some cases, exaggerated through artificial selection.
“It all depends on popularity and what people like,” Lyons told Live Science. “Even if one cat strain becomes so popular that the breed’s appearance changes, the next new fad could send it back in a different direction.”
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