Miss Cuddlywumps reports on new research into the domestic cat genome
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What makes a cat a cat and not a penguin? The DNA.
Illustration by Chocahuète + fichiers commons
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Think of a domestic cat and her essential qualities. You are
picturing a lovely creature with a colorful coat, perhaps with long or textured
fur, a creature that will sit on your lap (or not) and purr to you (or not).
You are thinking of a small carnivore that devours (or not) the fish and
chicken dinners you serve him, a hunter with exceptional hearing and low-light
vision.
You are picturing the product of the information contained
within the cat’s genes. In that genome, some researchers at Washington
University School of Medicine in St. Louis have recently found some interesting
things, including evidence of feline domestication and of what sets cats apart
from other mammals.
DNA evidence of (semi-) domestication
Cats and humans have been together for “only” 9,000 years or
so (compared to the 30,000 or more years since domestic dogs arose from wolves).
Cats, though, “are really only semidomesticated,” according
to genetics professor Wes Warren, who was involved in the research. “They only
recently split off from wild cats, and some even still breed with their wild
relatives. So we were surprised to find DNA evidence of their domestication.”
The researchers compared genomes of domestic and wild cats
and found areas where changes have happened apparently as a result of
domestication. Changes were found in genes thought to be involved in memory,
fear, and reward-seeking, all of which could be important in domestication.
For example, cats might have started hanging around human
settlements because of the food (rodents) they found there, and humans might
have encouraged them to stay by offering rewards of more food. (And you all
know how a cat will hang around once you’ve given it food. That’s how She of
Little Talent got one of her real cats, Jack, a former stray who kept hanging
around the bird feeder. Now he’s semidomesticated and enjoys crunchy treats and
soft blankies.)
As the theory goes, the less fearful cats would hang around
more, getting more food rewards and having kittens who learned from a young age
to hang around humans and not be terrified of them, until eventually there
arose a type of cat whose genome was slightly different from its wild ancestors’.
The Birman’s white gloves
The researchers studied the genomes of some purebred cats,
including the Birman. They found that the Birman’s characteristic white paws are
linked to two small changes in one gene for hair color. All Birmans have this
genetic signature, which could be evidence that humans bred the cats
specifically for their adorable little white paws.
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A Birman cat. Note the adorable white paws,
a trait related to two small changes on a single gene.
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Comparing domestic cats to tigers, cows, dogs, and humans
The scientists also compared the domestic cat genome to
those of other mammals, looking for evidence of just what it is that makes a
cat a cat. Here is some of what they found:
- Cats and tigers have special genes for breaking down fats. This helps the cats, big and small, digest their fatty, all-meat meals.
- Cats don’t have as many genes for smell as dogs do. They don’t need as many because their hunting technique relies less on scent than on vision and hearing. However, cats have more genes that help them detect pheromones, which help them find mates and keep track of what other cats in the vicinity are up to.
- Cats have genes that allow them to hear across a greater range than other carnivores (into the ultrasonic range) to help them track prey.
- Cats have genes for improved low-light vision, important for a hunter on the prowl at dawn and dusk.
The research was published Nov. 10 in the
Proceedings of the National Academy of Sciences Early Edition.
Source
For more on cat DNA, see “Clues
to Cat History Written in DNA” and “Where
Purebred Cats Come From”
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