Red foxes living in the city are evolving traits associated with pets or livestock animals such as shorter snouts or smaller skulls among other physical characteristics, a new study suggests.

Dr. Kevin Parsons, of the University of Glasgow’s Institute of Biodiversity, Animal Health and Comparative Medicine explains that there are some important physical and behavioral differences between red foxes that live in the UK’s urban and rural environments, with the former becoming more similar to domesticated dogs.

The findings help further our understanding of how domestication processes take place and could help uncover how humanity domesticated other animals in the past

Wild is out of fashion

“We wondered whether this change in lifestyle was related to adaptive differences between urban and rural populations of red foxes,” said Dr. Parsons, of the University of Glasgow’s Institute of Biodiversity, Animal Health and Comparative Medicine, lead author of the paper.

“We assessed skulls from hundreds of foxes found within London and the surrounding countryside and saw that urban foxes had a smaller brain size capacity but also a different snout shape that would help them forage within urban habitats. There was also less of a difference between males and females in urban foxes.”

Coronavirus lockdowns around the world have created space for wild animals to roam (or even take up residence in) our cities more often. However, they present a very different habitat compared to the wilds, and many species just can’t adapt to long-term life in the city.

But some are especially good at it. Red foxes are one such species, and they’ve become quite prevalent in urban areas, especially in the UK. They’re also adapting to be better suited to life here, and to living in proximity to humans.

The team explains that the changes they documented in the study are the same that they would expect to see during a domestication process. The foxes are far from being domesticated, but they are taking on characteristics seen in domesticated animals. The team explains that their findings here can help us piece together how dogs, for example, evolved into pets from predators.

The changes observed by the team are “primarily involved with” the length of their snouts, braincases, and reduced sexual dimorphism (i.e. physical differences between the two sexes). Urban foxes have shorter snouts and smaller braincases, the paper explains. Differences between the two populations are “widespread and related to muscle attachment sites”, they add and likely driven by different requirements for cognitive ability and physical characteristics when feeding in the two habitats.

These changes matched up with what would be expected during a domestication process. In other words, while urban foxes are certainly not domesticated, they are changing in ways that move them closer to what is seen in many domesticated animals.

“This is important because human-animal interactions are continuous and some of the basic environmental aspects that may have occurred during the initial phases of domestication for our current pets, like dogs and cats, were probably similar to the conditions in which our urban foxes and other urban animals are living today,” adds co-author Dr. Andrew Kitchener from National Museums Scotland.

The paper “Skull morphology diverges between urban and rural populations of red foxes mirroring patterns of domestication and macroevolution” has been published in the journal Proceedings of the Royal Society B: Biological Sciences.