The diets of ancient foxes may reveal the ecological impacts of human activities in the past, according to a new study from the University of Tübingen. The researchers have discovered that foxes were already eating human leftovers 42,000 years ago.
Wild foxes feed on scraps left behind by larger predators like bears and wolves. However, the closer they live to civilization, the more their diets consist of food left behind by humans.
A team of researchers led by Chris Baumann theorized that if this behavior dates back to ancient times, then fox diets may be useful indicators of human impacts on ecosystems of the past.
The investigation was focused on the remains of various herbivores, large carnivores, and foxes from several archaeological sites in southwest Germany dating to the Middle and Upper Palaeolithic. The researchers analyzed carbon and nitrogen isotopes and compared them among the animal remains.
At sites older than 42,000 years, when Neanderthals infrequently occupied the region, fox diets were found to be similar to the local large carnivores. However, in the younger sites frequently occupied by Homo sapiens, the animals developed a more unique diet consisting largely of reindeer.
“We observed that during the Middle Palaeolithic period, when Neanderthals sparsely populated the Swabian Jura, the niches occupied by foxes suggest a natural trophic behavior,” wrote the study authors. “In contrast, during the early Upper Palaeolithic periods, a new trophic fox niche appeared, characterized by a restricted diet on reindeer.”
While reindeer are too large for foxes to hunt, they are known to have been important game for humans at this time in history.
The findings suggest that during the Upper Palaeolithic, the foxes made a shift from feeding on scraps left by local large predators to eating food left behind by humans. This means that the animals started relying on human food at least 42,000 years ago.
“Dietary reconstructions of ice-age foxes have shown that early modern humans had an influence on the local ecosystem as early as 40,000 years ago,” said the reseachers. “The more humans populated a particular region, the more the foxes adapted to them.”
The study is published in the journal PLOS ONE.