Something’s up with raccoons. Scientists have recently reported that those living in US cities have evolved much shorter snouts than their rural counterparts, a sure sign that urban “trash pandas” have self-domesticated in response to human presence.

Biologists from the University of Arkansas at Little Rock studied thousands of images of North American raccoons (Procyon lotor) captured in the US between 2000 and 2024. Using computer software, they analyzed the skull and snout size of the animals, comparing those living in cities to those in rural settings. 

“I wanted to know if living in a city environment would kickstart domestication processes in animals that are currently not domesticated,” Dr Raffaela Lesch, lead study author and an assistant professor of biology at the University of Arkansas at Little Rock, said in a statement. “Would raccoons be on the pathway to domestication just by hanging out in close proximity to humans?”

Their work revealed that the urban-dwelling raccoons had a 3.56 percent reduction in snout length, suggesting they were experiencing a phenomenon known as domestication syndrome.

Domestication syndrome is a collection of traits that emerge when animals adapt to living closely with humans. Decreased aggression is a prime feature, but it also includes attributes like floppier ears, more varied fur patterns, smaller teeth, smaller brains, and shorter muzzles.

The most obvious example can be seen in the differences between domestic dogs and their wild canine cousins, like wolves and foxes, but domestication syndrome is also evident in cats, horses, cattle, pigs, and other animals that have a tight relationship with humans.