Friendly felines first cozied up to humans in the Fertile Crescent of the Middle East at least 9,500 years ago, not in Egypt as commonly thought, an international team of researchers reported Thursday.
Archeological evidence had previously suggested the date for the taming of wildcats, but the new study, published in the online edition of the journal Science, provides genetic evidence that confirms the origin of domesticated cats.
Farmers in what now are Saudi Arabia and Israel probably were happy to have the cats around to protect stored grain from vermin.
"This was much earlier than Egyptian civilization," said geneticist Carlos Driscoll, lead author of the study and a graduate student at the Wildlife Conservation Research Unit at the University of Oxford.
In addition to providing insight to the origin of a popular human companion, the study offers a promising new method for combating the extinction of some modern wildcats.
For the study, researchers sampled genetic material from 979 cats, including animals at fancy cat shows, feral cats and wildcats trapped in Mongolia and Kazakhstan.
They were able to sort the cats into six categories according to 36 DNA markers. Domestic cats fell into the same group as Fertile Crescent wildcats, suggesting that the two share a common ancestor.
In their analysis, they discovered genetic signatures of at least five female forebears of modern housecats, indicating that there was more than one instance of domestication.
The scientists also looked for evidence of interbreeding among domestic and wild cats. The housecat gene pool, they found, was relatively free of wildcat DNA.
"What we're doing is part of a genetic background check on the domestic cat," Driscoll said.
That's important because cats are often used in biomedical research, and scientists need to know that feline subjects in one study are the same as subjects in any other study.
On the flip side, the researchers found that many wildcats have domestic genes.
The dilution of wildcat populations by DNA from housecats is the biggest threat to wildcat survival, said Pat Bumstead, director of the International Society for Endangered Cats, based in Canada.
"There's no point in conservation if the animal is half a domestic cat," Bumstead said.
Scottish wildcats, for instance, are endangered because of extensive interbreeding with feral domestic cats. The wildcats, which may number as few as 400, are so similar to housecats that it is almost impossible to distinguish a pure wildcat from a hybrid just by looking at it.
Armed with the genetic information, Driscoll hopes to identify full-blood Scottish wildcats for breeding and conservation programs.