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."

Marshall says the evidence is "terribly exciting" because scientists have never before seen documentation this old of the pathway through which wildcats stepped over the threshold and into the home.

"It's very hard to find, archaeologically, exactly what relationship caused domestication," she said. "Usually we can find the time or the place. It's been speculated that for modern cat behavior that cats were attracted to early farmers, but it wasn't known for sure. But what this shows us is, yes, there was food for ancient cats in ancient farming villages, and that they helped the farmers out, making it a mutualistic relationship, by eating rodents."