The ancestors of modern cats followed early farmers into Europe but weren’t pets, according to a recent study. Nitrogen isotope ratios in the bones of six cats from Neolithic Poland suggest that these ancient cats hunted rodents that ate human farmers’ crops, but they didn’t eat quite the same diet as local people and their trusty domestic dogs. In other words, the cats lived a lifestyle similar to modern coyotes.

Cats lived near people but not with them

All modern cats trace their lineage back to Near Eastern wildcats; in fact, it’s still a bit tricky to tell the domestic cats from these wildcats based on their DNA. Sometime around 5,300 years ago, it seems that these wild cats noticed that rodents like mice, voles, and hazel grouse flocked to human settlements to eat crops and food stores. The rodents came for the grain, and the cats came for the easy, abundant prey.

Between 4,200 and 2,300 years ago, a population of early farmers from Central Asia moved into Europe, where they interacted with the hunter-gatherers who already lived there. Some wild cats tagged along; archaeologists found Near Eastern wildcat skeletons in Poland from around the same period. Archaeologist Magdalena Krajcarz of Nicolaus Copernicus University and her colleagues say the cats weren’t really traveling with the humans—they were just following their prey. (This argument does sound a bit like a cat wrote it.)

Krajcarz and her colleagues examined the chemical makeup of bones from six Near Eastern wildcats found in southern Poland. As nutrients get passed up the food chain, nitrogen-15 tends to get passed along more than the other stable nitrogen isotope (nitrogen-14), so the ratio between them can suggest what an animal was eating. Domestic crops also tend to be richer in nitrogen-15, because it gets added in the form of manure used as fertilizer, so a high ratio of nitrogen-15 can also suggest a diet rich in domestic crops—or in meat from animals that ate those crops.

The Near Eastern cats had fairly high levels of nitrogen-15. But what’s more important is that the cats’ levels lined up very closely with the nitrogen-15 levels in the bones of local crop-eating rodents. It was the molecular version of a smoking gun, suggesting that about 75 percent to 95 percent of the cats’ menu consisted of rodents that fed on farmers’ crops and food stores.

On the farm

But when Krajcarz and her colleagues compared the cats to ancient people and domestic dogs from nearby settlements, like Bronocice, they found that people and their dogs had even higher nitrogen-15 levels than cats. That suggests that people were eating a diet based almost entirely on farmed crops and were sharing their food with their canine companions.

Cats, on the other hand, seem to have lived near settlements and taken advantage of some of the things that go along with having humans as neighbors, like access to plenty of well-fed mice. Their slightly lower—but still high—nitrogen-15 values suggest that they lived mostly on crop pests but also hunted other kinds of prey.

Ecologists call this lifestyle synanthropy, and today you can see it in modern urban foxes, coyotes, raccoons, and crows. For cats, synanthropy was a step on the way to domestication—on their terms, of course. The earliest cat remains found in human settlements date to the Roman period in Poland, 3,000 years later, and their nitrogen-15 levels are much closer to humans and dogs.

When the first Near Eastern wildcats followed farmers into Europe, they found themselves splitting an ecological niche with European wildcats that already lived there. The European wildcat bones Krajcarz and her colleagues looked at had nitrogen-15 levels similar to the Near Eastern cats but spread across a wider range. That suggests that, while the Near Eastern cats mostly hunted crop pests, the European cats just added the crop-eating rodents to their local menus. Perhaps that partially explains why Near Eastern cats, but not European ones, eventually ended up domesticated.

Paws for reflection

All six of the Near Eastern cats Krajcarz and her colleagues looked at came from caves in the hills overlooking the fertile lowlands where people farmed. They seem to have ended up in the caves either because that’s where they lived and died or because larger predators hauled them home as a snack. People lived in the highlands, in smaller and sparser groups than the farming settlements in the valley below. But there’s no evidence that they buried the cats.

Those caves were 30km to 45km (19 to 28 miles) away from nearby large farming settlements in the valley. That suggests something about these six cats’ range, but there’s a lot it doesn’t tell us. Archaeologists haven’t found cat bones at any of the Neolithic settlements in Poland, so there’s no evidence yet to tell us whether cats lived and hunted in even closer proximity to people or if some actually lived in human homes or food-storage structures.

PNAS, 2020 DOI: 10.1073/pnas.1918884117  (About DOIs).

https://arstechnica.com/?p=1691841