(CNN)Humans aren't the only creatures who love leftovers. It turns out foxes during the Ice Age had a craving for them, too.
Arctic foxes ate food scraps left by humans around 42,000 years ago, according to a new study published Wednesday in PLOS ONE journal.
Researchers studied fox remains dating back to the ice age found at archaeological sites in southwest Germany and discovered that foxes ate similar foods to humans during that time.
Homo sapiens hunted animals for food during the ice age, and human hunting habits gave the foxes an easy food source, according to Chris Baumann, a research associate and doctoral candidate at the University of Tübingen in Germany and one of the study authors.
"Foxes are very flexible and opportunistic in their diet," Baumann said. "They use the resources that are easiest to access."
The foxes largely ate reindeer. The researchers learned this by testing certain isotopes in the ancient fox remains that would reveal what the animals ate.
Reindeer are too big for a fox to kill, but humans liked to hunt and eat them, according to the study. Foxes who lived near humans could get at the reindeer remains, Baumann said.
Foxes also had a taste for mammoths, which was another popular animal for humans to hunt and eat. Some Arctic foxes, Baumann said, did show evidence of eating mammoths. But because humans didn't bring whole mammoths to the caves, the foxes likely came across the carcasses left in the wild.
"Humans only brought the usable pieces of the mammoth into the caves, whereas they took the whole reindeer body and butchered the reindeer near the cave," Baumann said.
"We assume that these animals scavenged at human kill sites," Baumann said. "It is also possible that they fed on mammoths that died naturally."
Arctic foxes from 42,000 years ago are very similar to the Arctic foxes of today, according to Baumann, and other modern foxes also have similar eating habits.
"In cities, modern red foxes eat scraps; in the fields, they catch mice or even eat fruit; and in the rough Arctic, Arctic foxes follow polar bears and feed on their prey," Baumann said.
The impact of foxes eating food scraps left by humans extends much further than simply filling their stomachs. Baumann said that humans "change the appearance of the planet" and influence the environment. Through this study, he can confirm that that influence began much earlier than the extinction of large ice age animals.
"That humans are at least partly responsible for the extinction of the Ice Age megafauna is quite certain from a scientific point of view," Baumann said in an email statement. "That our ancestors also had an influence on other animals so familiar to us today, and that they even benefited from the presence and ecological impact of humans, is new."
In the future, Baumann said he hopes to test his findings at other archaeological sites or expand to see if other animals like crows that are adapted to humans, adapted much earlier than originally thought.