And now, feline experts say they've surpassed the dog and become the most popular pet on earth. But how did the cat evolve from a wild animal to a pampered pet? In the upcoming National Geographic Channel documentary Explorer: Science of Cats, anthropologists and feline geneticists trace the evolution of the cat.

Dr. Leslie Lyons leads a research team studying the genetics of the domestic cat at the University of California, Davis School of Veterinary Medicine. In the interview excerpted here, she explores the origins and domestication of the house cat:

AP: Feline geneticists say cats "domesticated themselves." What does that mean?

Lyons: We say cats adapted themselves to us rather than the other way around. As humans became farmers, we started a civilization. And civilization has grain stores and refuse piles, two things that draw rodents. Cats started coming closer to households to eat the rodents, filling the niche that humans developed. Cats were the first to come close to humans. We tolerated them because they ate the rodents, and cats tolerated humans because we provided food.

Q: How is this different from the domestication of dogs?

A: Dogs were domesticated much longer ago when we were hunter-gatherers. Unlike cats, we actively domesticated them. Probably we took wolf cubs and tried to tame them, raised them to be companions and to use for protection. Horses are like that too, we had to go out and capture and tame them before we could use them.

Q: Cats are now found in every corner of the globe: Feline experts estimate that there are 600 million cats in households on six continents. Where did cats first come from? Who were the first people to enjoy them as pets?

A: There is archaeological and genetic evidence to show that cats first originated in the fertile crescent. We took genetic samples in Egypt, Turkey, Lebanon and Iran and they are all tied together because that was the seat of cat domestication. Most people know a little about the link between cats and ancient Egyptians; cats weren't exactly worshipped but they were very important to the society and the religion. There are many early Egyptian accounts of cats living in households, and this is seen in paintings as well. And for ancient Egyptians who worshipped Bast, the goddess of family and fertility who has the head of a cat, mummified cats became like an offering to Bast — like if you were Catholic you might go into church and light a candle, so people would buy cat mummies and offer them to the goddess.

Q: From there, where did cats go? How did they get to the United States?

A: Cats spread through Asia, where they also became important to societies there: An all-white cat is considered good luck, for example. They came here, to North America, with the Pilgrims, on the boats to help with the rodent populations. There are no domesticated cats that are indigenous to America or Australia, they all came over on boats.

Q: Where did superstitions about cats — that black ones are unlucky, for example — come from?

A: I think most superstitions about cats came from people's fear of them. They're uncanny animals. They're aloof, but then they suddenly appear and startle people. They're also great climbers and can jump three or four or five times their own heights. It's surprising and maybe frightening for people to see them on the ground and then suddenly up on the wall. Also their eyeshine is interesting and strange — their eyes have a reflective layer that is dramatic in darkness.

Q: And at least in western societies they became associated with witches, right?

A: Right. Actually their association with witches might have had a dramatic impact on society. During the time of the bubonic plague, cats were persecuted along with witches. But the plague was carried by fleas that are on rats, and a dense cat population would kill rats. As we persecuted the cats, there were fewer cats and more rats, which meant more fleas carrying plague. The lack of cats contributed to the spread of the plague.

Q: Are there any remnants of wild behavior in the cats we keep as pets today, or did cats completely change when they became domesticated?

A: Pretty much all the behavior your house cats show today are variants of wild behaviors they've always had: play hunting, napping, how they eat and drink. For example, people complain that their cats wake them up early for breakfast. That's because cats like to hunt at dawn and dusk. They wake you up at dawn because that's when they're genetically programmed to want to eat.

Enlarge National Geographic Television A Bambino cat is seen in the upcoming National Geographic Channel documentary Explorer: Science of Cats.