Graham Racher / Alamy
We shouldn’t be surprised by how well foxes can survive by scavenging from our food leftovers – it is a behaviour that is tens of thousands of years old.
The ancestors of today’s foxes began living on humans’ food remains about 42,000 years ago, according to an analysis of animal bones found in Germany. “It’s the same as how they behave today in towns,” says Chris Baumann at the University of Tübingen in Germany.
Today, red foxes (Vulpes vulpes) and Arctic foxes (Vulpes lagopus) prey on small rodents in the wild as well as scavenging from the carcasses of animals, often those killed by large predators like bears and wolves. But the closer they live to towns and villages, the more their diet is made up of people’s food leftovers. “They’re very flexible,” says Baumann.
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He and his team analysed animal bones, including those of foxes, bears and wolves, found at sites in south-west Germany. The sites had been dated to three time periods: older than 42,000 years ago, when Neanderthals were the only humans living in the region, and two later periods when modern humans had moved in, lasting until 30,000 years ago.
By measuring the different isotopes of carbon and nitrogen in the bones, the team could work out what the animals had been eating. In the oldest period studied, foxes had eaten a mixture of animals, and these were likely to have been killed by bears, wolves and lions.
But after around 42,000 years ago, some of the foxes had switched to eating mainly reindeer. None of the other carnivores were mostly eating reindeer, so the foxes couldn’t have been scavenging from the kills of wolves, for instance.
While humans at the time ate a range of animals, including mammoths, “in cave sites, we find a lot of reindeer bones, because they are easy to transport as whole bodies to the caves”, says Baumann. “And if humans butchered them there, it would have produced food waste.”
Looking at the diet of foxes in other areas may become a new source of information about how ancient humans lived, says Baumann.
Journal reference: PLoS One, DOI: 10.1371/journal.pone.0235692
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