This post, adapted from one of the facts in my upcoming ebook “50 Facts About House Cats (And Where They Come From),” builds on last week’s post on moggies and fancy-cats.
Purebred dogs get genetic testing, yet no cat registry requires DNA tests to validate identity, pedigree, and parentage.
That’s because geneticists are struggling to identify feline fancy-breeds in the lab.
One problem is that all cats look alike under the skin. Yes, that’s hard to believe, considering all the various feline looks today . . .
. . . but it’s true. Almost all of the genes in these animals are the same.
Another problem for researchers: cat breeding hasn’t been around long enough for clear-cut genetic breed differences to accumulate.
They’re working on it, though. Four different regional genotypes have been found, as well as multiple domestic cat “races.”
This all helps the boffins categorize the forty-plus modern cat breeds.
What are the five informal categories?
Short answer and details are best combined here.
While this isn’t formalized in the cat fancy, a review of scientific literature finds the following (exactly which breed goes where depends on the study; Menotti-Raymond and others, in the source list, used these examples–your mileage may vary):
1. Mutations: A spontaneous genetic change produces an interesting look that cat fanciers develop into a new breed.
- Scottish Fold
- Selkirk Rex
2. Natural breeds: A domestic cat line that developed in one region, somewhat isolated from other cat groups. Fancy-cat traits still appear in local moggies. While rules vary by registry, these moggies might be used in fancy-breeding programs to improve the gene pool.
- Japanese Bobtail
- Norwegian Forest Cat
- Turkish Angora
- Turkish Van
3. Established cat breeds: This is what most of us think of as a pedigreed cat–one bred to conform to a certain standard. You may be surprised that some familiar breeds, going back many centuries, are in this category. Here’s the basic difference: local moggies aren’t used in the breeding programs. Established breeds soon lose their distinctive features when bred with moggies.
- American shorthair
- British Shorthair
- Cornish Rex
- Devon Rex
- Egyptian Mau
- Maine Coon
- Russian Blue
4. Variants: These are breed varieties. Instead of saying, “It’s a nice sundae, but let’s substitute pistachio ice cream for vanilla”, a cat fancier might say, “What if a Persian cat had Siamese points?” and then adjust the breeding program to alter the appropriate gene. In this example, the result is typically called either a Himalayan or Colorpoint Longhair variant of the Persian, but varieties can also be full-fledged breeds in some registries.
- American Curl (OG breed: American Shorthair)
- American Wirehair (American Shorthair)
- Balinese (Siamese)
- Colorpoint Shorthair (Siamese)
- Exotic Shorthair (Persian)
- Himalayan (Persian)
- Oriental Shorthair (Siamese)
- Somali (Abyssinian)
5. Hybrid cat breeds: These are exactly what they sound like: crosses between different breeds, between moggie and fancy-cat, or even with another species. Technically, the Scottish Fold is a hybrid as well as a mutation breed because it was developed by crossing pedigreed Shorthairs with moggies.
- Bengal (domestic cat x Prionailurus bengalensis)
- Bombay (American Shorthair x Burmese)
- Ocicat (Abyssinian x Siamese x American Shorthair)
- Tonkinese (Burmese x Siamese)
Are cat breeders making cats evolve?
Short answer: Sort of. By selectively breeding cats, fanciers do change feline genotypes (the set of genes that make up individuals in a group) for better or worse. But unlike natural selection, the results are usually temporary. The major evolutionary effect of breeding is probably domestication itself.
Details: You and I might not see any difference between a wavy-coated Cornish Rex and a wavy-coated Devon Rex, but breeders (who are essentially practical geneticists) know that each of these unusual coats comes from a different genetic mutation. That’s enough to call them two different breeds.
However, both Rexes are still one species–the domestic cat, which is a product of evolution through natural selection (cat breeding is artificial selection).
Despite our preconception of natural selection as a brutal fight, “survival of the fittest” is also a very creative process that subtly works on a population’s store of genetic variability over deep time.
It’s complicated and not at all obvious–a paleontologist named George Gaylord Simpson first pointed it out almost a century after Darwin–but the proof is all around us.
Cats clearly are not plants or bears, but cats and bears only exist because at least one population of carnivorous mammals somewhere (founders of the order Carnivora) had enough variability to evolve into these two very different lines.
That takes geological time-spans, of course, but cat breeders don’t need calendars going back to the Cretaceous to manipulate a cat’s color, coat quality, and/or body shape.
Such characteristics are controlled by just a few of the tens of thousands of genes in the domestic cat genome.
If you want to get into details, check out this seven-video playlist on cat coat colors (note: it doesn’t cover the polygenes that affect body shape and some other characteristics; those modifier gene are less well understood):
In some ways, breeders are adding to the domestic cat’s genetic “bank account” by combining features in unique ways. But they are also insulating cats from the seriously brutal side of evolution.
For instance, without human assistance, a Peke-faced Persian isn’t going to live long enough in the wild to pass its genes along. Even long hair might be detrimental to the cat’s survival chances; some observers note there aren’t many longhairs in feral cat groups.
Another problem is inbreeding. To a limited extent, it’s necessary to maintain many fancy-cat lines but it makes the genetic “bank account” balance plummet. Inbreeding also passes along harmful genes, like those causing hereditary diseases in some breeds.
Probably the biggest evolutionary effect of cat breeding shows up in feline behavior.
Feral cats don’t fully revert to wildness even after several generations. Their kittens make good pets, too, if socialized early enough in life.
Domestication may not be complete in cats yet, but it already has taken root.
It would be nice to come across a study of the long-term evolutionary effects breeding is having on domestic cats.
Until then, all we can do is look at the colors and shapes that moggies now have, compared to their Ancient Egyptian “African wildcat 1.1” look. What other effects of artificial selection will their descendants display in the distant future, when the cat fancy, and perhaps our whole civilization, have vanished?
Featured image: Himalayan/Colorpoint Longhair, by Hilary Heard Gurley via Wikimedia, CC BY-SA 4.0
Driscoll, C. A.; Macdonald, D. W.; and O’Brien, S. J. 2009. From wild animals to domestic pets, an evolutionary view of domestication. Proceedings of the National Academy of Sciences, Supplement 1. 106:9971-9978.
Kurushima, J. D.; Lipinski, M. J.; Gandolfi, B.; Froenicke, J. C.; Grahn, J. C.; Grahn, R. A.; and Lyons, L. A. 2012. Variation of cats under domestication: genetic assignment of domestic cats to breeds and worldwide random-bred populations. Animal Genetics. 44:311-324.
Lipinski, M. J.; Froenicke, L.; Baysac, K. C.; Billings, N. C.; and others. 2008. The ascent of cat breeds: genetic evaluation of breeds and worldwide random bred populations. Genomics. 91(1):12-21.
Menotti-Raymond, M.; David, V.; Pflueger, S.; Lindblad-Toh, K.; and others. 2008. Patterns of molecular genetic variation among cat breeds. Genomics. 91:1-11.
Robinson, R. and Pedersen, N. C. 1991. Normal genetics, genetic disorders, developmental anomalies and breeding programmes, in Feline Husbandry: Diseases and Management in the Multicat Environment, 61-128. Goleta: American Veterinary Publications. https://www2.vetmed.ucdavis.edu/ccah/cats/feline-husbandry-book.cfm .
Turner, A., and M. Antón. 1997. The Big Cats and Their Fossil Relatives: An Illustrated Guide to Their Evolution and Natural History. New York: Columbia University Press.
Wikipedia. 2018. Cat genetics. https://en.wikipedia.org/wiki/Cat_genetics Last accessed September 2018.
Wright, M., and Walters, S. 1980. The Book of the Cat New York: Summit Books.