Why do people keep cats?
As a non-cat person, I have long been perplexed by this state of affairs, in which millions and millions of humans around the world have wound up sharing a home with these odd (and—fine—kind of cute) creatures. How did this come to be?
For a long time, archaeologists have hunted for early evidence of this relationship between humans and cats. They've found a wildcat buried near a human on Cyprus from about 9,500 years ago, a proximity suggesting some sort of relationship between the two species. And from ancient Egypt there are paintings, about 4,000 years old, that depict cats, often sitting beneath the chairs of women.
But these bits of history did little to reveal how man and cat first reached, paw to hand, across that species divide.
Now, new archaeological evidence from China, published today in the Proceedings of the National Academy of Sciences, documents for the first time a chain of events that forged the relationship between human and feline.
The story begins with agriculture. About 5,560-5,280 years ago in the Shaanxi region of central China, humans were experiencing an agricultural boom. "It's early, but it's not the earliest farming in China," the paper's co-author, Fiona B. Marshall of Washington University, told me. "It's from the time when farming really took off, when it was successful."
They had small villages, with clusters of homes, cemeteries, and communal areas. They kept pigs and dogs and grew crops, primarily millet but a bit of rice, too, which they kept in ceramic vessels.
Now, these farmers had a bit of a problem: rodents. Archaeologists at the village of Quanhucun found an ancient rodent burrow that led right into an ancient grain storage pit. Storage vessels found at the village feature angles and slippery surfaces, design elements that seem to indicate an intention to protect the contents from thieving zokors. Rodent bones from the site contain evidence of millet consumption. "Clearly those rodents were eating the farmers' grains," Marshall said.
But the farmers had some help in their battle against the rodents: cats.
Archaeologists found eight cat bones in pits across the sites. When they looked at isotopes in the bones, they could detect traces of what those cats had eaten, and wouldn't you know it, the cats had been eating animals that had been feasting on human grain.
Marshall explained to me, "There are different photosynthesis pathways for plants in different places. If it's hotter or closer to the tropics, they more often have what we call a C4 pathway, whereas if it's cooler, they are more likely to have a C3 pathway. Where Quanhucun is, it's an area where the vegetation would be C3. The deer were clearly eating C3 plants. But the people and the pigs and the dogs, they were all eating C4 plants, and C4 had to come from the millet, which was cultivated and brought into that region. So it had a special signature of its own." The rodents and the cats all showed signs of that C4 pathway, indicating a path from human cultivation, to rodent, to cat.
And, soon enough, to pet: It could not have been long before farmers realized the utility of keeping the cats around, which would have led them to support the cat population, "by a) not killing them, and by b) even helping them in various ways—letting them stay in the warmth, providing foods," Marshall said. Unfortunately, though, there is not much evidence of that phase of the process. One solitary clue: One of the bones includes teeth that appear to be from a much older cat, suggesting "at the very least that it was doing well in that environment."