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From NPR News, this is ALL THINGS CONSIDERED. I'm Audie Cornish.
ROBERT SIEGEL, HOST:
And I'm Robert Siegel. Cats come with a variety of distinctive coat patterns. Some have stripes, some blotches and some come in solid colors. Well, now scientists have figured out that some of the genetic pathways that explain how that happens. And, as odd as this may seem, knowing the genes involved in cat coloration may teach us something about why humans get sick. NPR science correspondent, Joe Palca, explains.
JOE PALCA, BYLINE: Scientists have identified 37 different species of cats living on Earth today. And a few years ago, they worked out the genetics of where those cats all came from.
STEPHEN O'BRIEN: The modern cats descended from a middle size cat, weighed about 20, 30 pounds that wandered around Asia 10 million years ago.
PALCA: Stephen O'Brien has spent a good fraction of his career studying cat genetics. He says in the 10 million years since cats started wandering out of Asia, they have evolved into eight different lineages. For example, there's a group related to the roaring cats, like lions and tigers.
O'BRIEN: The group related to the house cat, the group related to the ocelots, a group that include the cheetah and the puma. And that gave us a backdrop for trying to get at changes that occurred in those lineage with respect to the genes that are allowing one cat to do this...
(SOUNDBITE OF CAT MEOW)
O'BRIEN: Another cat to do that...
(SOUNDBITE OF ROAR)
PALCA: Nice, kitty. Despite these differences, cats tend to look like cats, right down to their coloration.
O'BRIEN: Some cats are spotted, some cats have stripes, some cats have what we call blotches. And other cats don't have any of that, they just have a black or a lion-like color.
PALCA: O'Brien and some of his colleagues at the Hudson Alpha Institute for Biotechnology in Huntsville, Alabama, decided to try to figure out which genes are involved in making these color patterns. And now they've found the three genes that appear to play the biggest role. They report their results in the latest issue of the journal Science. Now, you may be thinking at this point, so what? Why waste time researching something as trivial as the genetics of cat color? O'Brien has heard that question.
O'BRIEN: Often when you're asked to justify it in terms of some medical benefit or something like that, it's a very torturous exercise.
PALCA: He admits this work might just be important for understanding the genetics of cat coloration. On the other hand...
O'BRIEN: It's curious that they have this kind of variation in not only in cats, but we also have this kind of variation even in humans.
PALCA: Different skin colors, different hair colors. And O'Brien says the way genes related to coloration have evolved suggest they may be important for something more fundamental than outward appearance. Some researchers believe these genes may also be involved in resistance to infectious diseases. Cat coloration genes and human diseases? Well, maybe. Joe Palca, NPR News, Washington. Transcript provided by NPR, Copyright NPR.
Different lineages of cat with the same coloration got their looks in unique ways. The genetic variants that determine those patterns come from different mutations in the same genes. And that has some scientists thinking there may be more to the genes than meets the eye.
At this point it's just an interesting hypothesis, but it's possible that understanding cat coloration could help scientists understand resistance to infectious diseases.
Here's the connection. Stephen O'Brien and colleagues at a variety of institutions including the Hudson Alpha Institute for Biotechnology in Huntsville, Ala., and Stanford University in California have worked out some of the genetic pathways that explain why "some cats are spotted, some cats have stripes, some cats have what we call blotches, and other cats don't have any of that, they just have a black or a lion-like color," says O'Brien.
They spell out the explanation in the latest issue of Science.
O'Brien says different lineages of cat have the same kinds of coloration, but they got them in unique ways. The genetic variants that determine those patterns come from different mutations in the same genes.
When geneticists see that kind of pattern of mutations over time, they figure those genes must be doing something that confers an important survival advantage because they stick around. That's evolution.
Now, it's possible that the advantage is simply camouflage to avoid predators or stalk prey, but O'Brien believes something else may be going on.
"Many of the genes involved in coat color sit on the surface of cells," he says. "Viruses are always looking for things to jump on that can allow them to stick and then invade a cell." No one has explicitly made the connection with the cat coloration gene, but they're in the right place.
There are reported examples of skin pigment genes playing a role in response to invading organisms. "Melanin plays an evolutionary ancient role in insect immunity to malaria," writes Michael Waisberg of the National Institute of Allergy and Infectious Disease in a recent article, although his research shows that melanin does not have a similar protective role for mice.
So maybe, maybe, maybe understanding the genes involved in cat coloration will tell us something someday about human infectious diseases.