Why Do Cats Hang Around Us? (Hint: They Can't Open Cans)
Friday, June 29, 2007
Your hunch is correct. Your cat decided to live with you, not the other way around. The sad truth is, it may not be a final decision.
But don't take this feline diffidence personally. It runs in the family. And it goes back a long way -- about 12,000 years, actually.
Those are among the inescapable conclusions of a genetic study of the origins of the domestic cat, being published today in the journal Science.
The findings, drawn from an analysis of nearly 1,000 cats around the world, suggest that the ancestors of today's tabbies, Persians and Siamese wandered into Near Eastern settlements at the dawn of agriculture. They were looking for food, not friendship.
They found what they were seeking in the form of rodents feeding on stored grain. They stayed for 12 millennia, although not without wandering off now and again to consort with their wild cousins.
The story is quite different from that of other domesticated animals: cattle, sheep, goats, horses -- and dogs, cats' main rivals for human affection. It may even provide insight on the behavior of the animal that, if not man's best friend, is certainly his most inscrutable.
"It is a story about one of the more important biological experiments ever undertaken," said Stephen J. O'Brien, a molecular geneticist at the National Cancer Institute's laboratory in Frederick, Md., and one of the supervisors of the project.
"We think what happened is that cats sort of domesticated themselves," said Carlos A. Driscoll, the University of Oxford graduate student who did the work, which required him, among other things, to befriend feral cats on the Mongolian steppes.
Today, there are 37 species in the family Felidae, ranging from lions through ocelots down to little Mittens. All domestic cats are descended from the species Felis sylvestris ("cat of the woods"), which goes by the common name "wildcat."
The species is indigenous to Europe, the Middle East and East Asia. The New World, Japan and Oceania lack wildcats. North America's closest counterpart is the lynx.
There are five subspecies of wildcats, and they look very much like many pet cats, particularly non-pedigree ones. The Scottish wildcat, for example, is indistinguishable from a barn cat with a mackerel tabby coat. These animals, however, are a true wild species. They are not escaped pets that have become feral, or reverted to the wild.
Driscoll and his collaborators, who included Oxford zoologist David Macdonald, took blood samples and ear punch biopsies from all wildcat subspecies as well as from fancy-breed cats, non-pedigree pet cats and feral cats. They analyzed two kinds of genetic fingerprints: nuclear DNA, which carries nearly all of an animal's genes and reflects inheritance from both parents, and mitochondrial DNA, which exists outside the cell nucleus, carries only a few genes and descends through the generations only from mothers.