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A comprehensive new study of DNA from ancient cat skeletons and mummies spanning 9,000 years traces the spread of cats from the Middle East to the rest of the world. The whole study, from conception to publication, took about 10 years—not least because of the work it took to find ancient cat remains.
“Cat remains are scarce,” says Eva-Maria Geigl, a paleogeneticist at Institut Jacques Monod and an author on the study. We don’t eat cats for food, so their bones don’t end up in ancient trash piles the way pig or chicken bones do. Geigl and her colleagues, especially Wim Van Neer, wrote to museums and collections asking to sample cat remains found in archeological digs. The team ultimately got bone, teeth, or hair from 352 ancient cats—including Egyptian cat mummies at the British Museum.
Not all of the remains yielded DNA. The Middle East environment is hot. In Egyptian tombs, where the cat mummies came from, it was also humid. “This is really a disaster for DNA,” says Geigl. The very act of extracting DNA can damage it, too. So to protect the DNA from heat released when bones and teeth are ground, the grinding process happens in a liquid nitrogen bath. Ultimately, the team was able to get DNA from 209 of the cats.