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Cat History: DNA study finds domestic-cat kin

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10:10am, June 27, 2007
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The Old World wildcat ranges from Scotland to China and down into Africa, but a new DNA study indicates that just one of its lineages, that of the Near Eastern wildcat, gave rise to today's domestic companions.

Domestic cats are still similar enough to their wild ancestor to belong to its species, Felis silvestris, explains Carlos Driscoll of the National Cancer Institute in Frederick, Md. He and his colleagues analyzed DNA from 979 cats, ranging from pampered darlings to wildlings caught in Kazakhstan. Their study resolves the wildcat family tree into five lineages. One group combines the Near East wild relatives and domestic cats worldwide, Driscoll and his colleagues report in the July 27 Science.

Driscoll says that the project grew out of efforts to conserve the surviving wildcats in the Scottish highlands. Killing them was forbidden, but an accused hunter protested on the grounds that biology couldn't prove that wildcats differ from domestic cats. To resolve the issue, David Macdonald of the University of Oxford in England encouraged Driscoll to sort out F. silvestris genetics.

Taxonomists had broken down the species into as many as 23 subspecies, but more-recent classifications had reduced those categories to three or four, says Driscoll. Following their new analysis, the number of wild subspecies could rise to five.

Driscoll, Macdonald, and their collaborators collected DNA samples from a range of sources, including the 33 show breeds, animals Driscoll trapped during a sojourn in Israel's Negev desert, and parts of Chinese desert cats from an Asian market. Regardless of where the domestic cats came from, their DNA looked more similar to that of the Near Eastern wildcats, the subspecies lybica, than to that of other subspecies, the researchers found.

The work "provides important independent support for the archaeological evidence," comments Melinda Zeder of the Smithsonian Institution's National Museum of Natural History in Washington, D.C., who studies animal domestication.

She says that studies of ancient sites show that nomadic people in the Near East became increasingly sedentary—harvesting abundant wild plants and animals—even before they domesticated crops and livestock. Those settlements offered new niches for animals, which could live among people and pick over their refuse. "It also seems now to be the context in which the wild cat became the tabby cat," says Zeder.

Jean-Denis Vigne of the National Museum of Natural History in Paris welcomes the new work as "an excellent paper." He and his colleagues have studied a cat skeleton that they say appears to have been intentionally buried near a human skeleton some 9,500 years ago in Cyprus. That's some 5,000 years before the earliest cat burials in Egypt, and Vigne has argued that Egyptians probably weren't the original domesticators of F. silvestris.

The DNA evidence doesn't have enough detail to say much about the date of domestication within the Near East, says Driscoll. Still, he says, it does open the way for DNA studies that may finally distinguish between domestic and wild Scottish cats.

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