Tuesday, January 24, 2012

Siamese Cats, Part Two

Jungle cats, kinks, and toes
The scientific evidence is in: Siamese cats are different from other cats in the world. But so are all domestic and feral cats in Southeast Asia.
In an article in Genomics (January 2009),  a group of researchers reported on their study of genetic data taken from both purebred and randomly bred cats living on five continents. They found that Southeast Asian cats were distinct in their genetic patterns from cats of North America, Europe, Africa, and even Japan. Why?
First reason:  Trade routes to the East.  The cat originated in the Middle East, and sea traders brought them on board when they traveled to India, seeking eastern treasures, including black pepper. (An alternate hypothesis states that the cat might have already gotten to India overland.) Travelers went from India to the Isthmus of Kra in Southeast Asia, en route to China, and the cat was introduced to Thailand around 100 A.D. Later, because of better policing of the sea, making ocean routes safer, traders began to travel to Java to reach China, avoiding Southeast Asia. Trade routes also crossed the Indian Ocean to the southeastern coast of Africa.
Sailors brought cats on board to control the stowaway rodent population. The cats freely left the ship, had blissful unions with the local cats, and came back aboard for the abundant food supply. Thus, European, African, and Asian cats shared their genetic material around the globe.
But after the change of route, Southeast Asian cats lived in isolation. They were isolated from the seafaring cats coming from the rest of the world, and to the north, mountains acted as a barricade for traveling on land. In the jungles, though, they may have found other friends…
Second reason:  The Southeast Asian jungle cats. The above picture is of a rare small jungle cat found in Southeast Asia, the marbled jungle cat. Is it possible that felis catus, our domesticated cat, interbred with the marbled cat, or some other small wildcat found in the region? Then this hybrid would have spread to other parts of Southeast Asia—but not beyond, because of the geographical barriers. The Siamese cat and all domesticated cats in Southeast Asia may be descended from this hybrid.
This hypothesis is supported by an anonymous post I found on the internet about modern-day Indonesian cats. The author claimed that they were very different from the ordinary domesticated cat. The cat had a muscular build and was a good jumper. It was more intelligent than the average domestic cat. His/her cat learned to open doors. I was astonished to read this, after writing last time about my cat who jumped up to turn the handle of the door. Could the Indonesian cat point to the origin of the Siamese cat, as this author was suggesting?
There are several small jungle cats that might have been the ancestor. After I read an interesting bit of information in an encyclopedia article on the marbled cat, I decided this one was a good possibility. This jungle cat’s meow is described as chirping, rather than the more continuous meow of the domesticated cat. The talking Siamese cat!
So is this the origin of the Siamese cat—the small-bodied, highly intelligent, vocally expressive feline? To prove it, we’d need another genetic study, comparing the Siamese cat’s DNA to that of the marbled jungle cat. That won’t be coming any time soon. The marbled cat is a very rare, almost endangered species, and even rarer in captivity than in the wild.

The jungle cat can explain a lot about the Siamese, but  there is still the question of the kinked tails. The answer in one word:  inbreeding, which brings out recessive mutations. Inbreeding doesn’t have to occur by design in a cattery—it happens in all populations of domesticated cats. A cat roams for a mate only as far as he needs to, and if the closest partner is his litter mate or his litter mate’s kitten, he’s not concerned. Kinked tails do not present any serious health issue, so cats with kinked tails thrive if humans allow them to.
My son Chris says a large percentage of the cats he sees in Laos have kinked, bobbed, or short tails. Sometimes the Southeast Asian’s cat kink is so severe that it results eventually in the loss of part of the tail, but even so, a cat can live quite well without its long tail. There may be an advantage in the jungle for having a long tail, which helps in jumping and climbing, but it is not a significant advantage for a village cat.
(It's important to note that kinked tails are not caused by the same gene that is responsible for the tailless Manx. This tailless cat is the result of another mutation caused by inbreeding on the Isle of Man, located in the Irish Sea, between Great Britain and Ireland. Manx is the adjective. The Manx cat's tailessness is caused by a defect of the spinal cord. In some cases, it only loses its tail, and becomes the Manx cat. But in about a quarter of kittens born, the defect is so great that the kitten must be destroyed, if it is not stillborn.)

The number of cats with kinked tails in Southeast Asia suggests that people not only accepted this “flaw”; they liked it! There is a story told in Thailand about the Siamese cat who kinked its tail in order to hold the rings of the princess who owned him. A cat with a kinked tailed in Thailand, even an ordinary street cat, is supposed to bring luck to its owner. The popularity of the short tail extends to Japan, where there is even a breed of bobbed-tail cats.
Cats with crooked tails are not so popular in the West. You do see cats with kinks (especially if they have some Siamese in them), but I’ve never heard them called lucky.
Another common result of inbreeding is the polydactyl, a cat with extra toes. Some in the cat fancy want to introduce polydactyls as a new breed. So far they have not been successful, but the interest shows that for the western cat, extra toes are a positive feature. (Polydactyls are found in Southeast Asian cats, too—I’ve seen pictures. But they are infrequent compared to the number of kinked tails. I assume this is because Asians do not consider extra toes lucky!)
I had two such cats when I was growing up. Tommy, the black cat, had seven toes on the front feet and six on the back; Boots had six toes (and claws) and another extra claw in between two toes on his front feet. This turned out to be lucky for him. Both cats were great hunters; the problem was that they sometimes encountered human hunters in the field where they roamed. Boots was shot in his front foot with a 22 rifle. It went clean through, missing every tendon and bone, possibly because his extra toe allowed ample room for the bullet’s path.


Everything I said above is correct, except that these mutations, when they occur, are dominant, not recessive, over the normal. While visiting Laos, I saw that a kitten had a straight tail, even though both its parents' tails were kinked. Puzzled, I did a little research and discovered that "kinked" was dominant over straight. The parents must have each had a recessive for straight, and when little Sarah received a recessive from each parent; Voila! a straight-tailed cat. In the same way, polydactylism is dominant over the normal five toes.  

Siamese Cats Part Three: How the Siamese came to Europe

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