DNA reveals how cats achieved world domination
Analysis of 9,000 years of cat remains suggests two waves of migration
TWO IF BY SEA Egyptian cats may have been transported by boat to far-reaching parts of Europe, Africa and Asia, a DNA study suggests. Early Middle Eastern farmers probably brought kitties and agriculture to Europe over land.
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The cat is starting to come out of the bag when it comes to revealing when and how wild felines became couch kitties.
A tale hidden in ancient cat DNA suggests cats were probably first domesticated in the Middle East. They later spread, first by land, then by sea, to the rest of the world, researchers report June 19 in Nature Ecology & Evolution.
Early farmers brought domesticated cats with them into Europe from the Middle East by 6,400 years ago, analysis of cat remains suggests. In a second wave of migration — perhaps by ship — Egyptian cats quickly colonized Europe and the Middle East about 1,500 years ago. Exactly where and when the animals were domesticated has been a matter of great debate. Researchers previously had only modern cats’ DNA to go on. Now, new techniques for analyzing ancient DNA are shedding light on the domestication process.
In the deepest dive yet into the genetic history of cats, molecular biologists Eva-Maria Geigl and Thierry Grange of the Institute Jacques Monod in Paris and colleagues collected mitochondrial DNA from 352 ancient cats and 28 modern wildcats. These felines spanned 9,000 years and regions stretching across Europe, Africa and Southwest Asia. Mothers pass mitochondria to their offspring. Scientists use variations of mitochondrial DNA, called mitotypes, to track maternal lineages.
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Tracking tabby
Wildcats and early domestic cats all looked the same with tiger-striped, mackerel coat patterns. New genetic data suggest the blotched tabby coat pattern that only domestic cats sport first popped up in Southwest Asia during the Middle Ages. (Boxes in chart represent ancient cats sampled in a DNA study. Blue indicates mackerel coats and red the blotched tabby pattern.) About 80 percent of modern cats carry this tabby mutation. The blotched look may have spread rapidly because it helped people distinguish their kitties from all the mackerel look-alikes.
About 10,000 to 9,500 years ago, African wildcats (Felis silvestris lybica) may have tamed themselves by hunting rodents and eating scraps from the homes of early farmers in the Middle East. People probably kept cats around as a means of vermin control. The arrangement “was mutually profitable for both sides,” says Grange. A person buried with a cat in Cyprus 9,500 years ago indicates that at least some people also had special relationships with the felines by that time (SN: 4/10/04, p. 227), Geigl says.
Before early farmers started migrating from the Middle East to Europe, European wildcats (Felis silvestris silvestris) carried one mitotype, called clade I, the researchers found. The first European cats found bearing a mitotype associated with domestication were a 6,400-year-old Bulgarian cat and a 5,200-year-old Romanian cat both with mitotype IV-A* — previously seen only in what is now Turkey. Because cats are territorial and usually don’t roam far, the finds suggest humans transported the cats to Europe.
Domestic cats in Africa, including three cat mummies from Egypt, had yet another mitotype called IV-C. That Egyptian cat signature began to invade the Middle East and Europe as early as 2,800 years ago, the team discovered. But the Egyptian incursion really took off between 1,600 and 700 years ago. By then, seven of nine European cats analyzed (including a 1,300- to 1,400-year-old cat from a Viking port on the Baltic Sea) and 32 of 70 of Southwest Asian cats had the Egyptian signature. That rapid spread may indicate that cats traveled by boat.
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Egyptian cats’ dominance could mean that something special made them especially attractive to ancient people, Geigl and Grange say. Domestic cats aren’t much different from wildcats, except that domestic cats tolerate people. Egyptian cats may have been particularly friendly, resembling the type of purring pet known today, the researchers speculate.
There’s not enough evidence to say that, says behavioral geneticist Carlos Driscoll of the Laboratory of Comparative Behavioral Genomics at the National Institutes of Health in Bethesda, Md. Egyptian cats may have benefitted from easy travel along established shipping and trade routes. Earlier cats may have been just as popular, but fewer people covering ground on foot would have had a harder time transporting them. Those early cats were “dependent on somebody putting a bunch of kittens in a basket and walking across a desert with them,” Driscoll says.
