Sugiyama thinks she knows how he did it. By analyzing the chemicals within the buried cat bones, she and her colleagues showed that jaguars and pumas likely came to Copán from distant regions and were kept in captivity for most of their lives. The city effectively had its own zoo, which was part of a wide trade network that sucked in wildlife from a larger area. For three centuries, wild animals—including the most formidable carnivores around—were brought in, housed, fed, and eventually used in ritual ceremonies.

“These people were interacting head on with some of the most powerful predators in the landscape—and that’s a feat we don’t see in many civilizations,” says Sugiyama. “We’ve always assumed that people in Mesoamerica only had the dog and the turkey—and camels and guinea pigs further south. But I think the dynamics between humans and animals [in the region] were much deeper.”

“We think of zoos and captive animals as a very modern thing, and also tend to think that animals in the past are merely food sources or beasts of burden,” adds Kelly Knudson, an anthropologist from Arizona State University. “This study helps us rethink both of these assumptions.”

In the 16th century, Moctezuma, ruler of Tenochtitlán, kept a famous private zoo full of thousands of animals. But in 2015, Sugiyama found evidence that Mesoamericans kept wild animals in captivity much earlier. She analyzed the remains of jaguars, pumas, golden eagles, and wolves that had been entombed in the great pyramids of Teotihuacan, Mexico, between the first and sixth centuries. Many of these showed signs of debilitating injuries, such as broken wings and legs. “These would have been fatal injuries in the wild,” says Sugiyama, who concluded that the animals had most likely been kept in captivity. By contrast, the cat remains from Copán bore no signs of such injuries. So Sugiyama turned to a different method.

Captive animals are more likely to be fed with agricultural crops like corn (or, in the case of big cats, with corn-fed birds). Compared with wild grasses, corn has unusually high levels of carbon-13—a form of carbon that’s much rarer and slightly heavier than the more common carbon-12. By measuring carbon-13 in the Copán bones, Sugiyama could tell if the cats had been raised on an artificial diet.

First, she analyzed a group of bones from the so-called Motmot tomb, which was constructed in the year 435. Within were the bones of a young woman, sitting cross-legged on a reed mat, three more human skulls, two deer, several birds and turtles, and the complete skeleton of a puma. The woman was likely a shaman, who was buried with her animal counterpart—the puma. And that cat, Sugiyama showed, had clearly been in captivity for a long time. It was getting more corn in its diet than a turkey found in the same tomb.