Urban Raccoons Are Showing Signs of Early Domestication, With Shorter Snouts Than Their Rural Cousins

The shorter faces of these city-dwelling trash bandits offer a telltale sign of domestication and line up with a leading hypothesis about animals that adapt to human-dominated environments, according to a new study

Marta Hill | Freelance contributor

November 21, 2025

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Your local trash pandas aren’t just getting used to digging through your trash can, they are actually starting to physically change in response to continued life around humans. In a study published last month in Frontiers in Zoology, researchers found that raccoons living in urban areas have shorter snouts than their rural counterparts do—a classic trait of domestication.

The research team, which included 16 students from co-author Raffaela Lesch’s class at the University of Arkansas at Little Rock, dug through nearly 20,000 images of raccoons in the United States from the community science platform iNaturalist. By comparing snout lengths to skull lengths, they found that urban raccoons’ snouts were 3.56 percent shorter than those of rural raccoons.

The concept of domestication may bring to mind a human-driven process of artificial selection, but that is not an accurate view, according to the paper. Domestication can start to occur without direct human involvement, as animals adapt to human environments. In the case of raccoons, trash availability may be enough to kickstart those changes.

“One thing about us humans is that, wherever we go, we produce a lot of trash,” Lesch tells Marina Wang at Scientific American.

The readily available mounds of human scraps encourage the animals to dig around searching for food, but they also reward a dampened fight-or-flight response, which helps them feed successfully despite interference from humans.

Raccoons in cities have learned to be “bold enough to raid garbage cans but polite enough” to avoid negative interactions with people, says Marcie Logsdon, a wildlife veterinarian at Washington State University who was not involved in the study, to Axios Seattle’s Christine Clarridge. “Raccoons have adapted incredibly well to our presence.”

Human environments are putting an evolutionary selection pressure on the raccoons, which seems to be leading them to develop smaller facial skeletons—just one of a handful of common traits that are known as domestication syndrome. Among animals that live closely with humans, researchers also often see curly tails, floppy ears, smaller brains and depigmentation in the fur.

The raccoon findings fit with past work surrounding urban foxes and mice, Adam Wilkins, a biologist at Humboldt University of Berlin who was not involved in the new study, tells Scientific American.

The results “indicate that once wild animals start spending time in the proximity of people, they become a little bit less afraid and perhaps even start showing physical signs of domestication syndrome,” he says.

A leading explanation for these changes is called the neural crest domestication syndrome hypothesis, which suggests that all the shifts are tied to a process in early embryonic development. Neural crest cells migrate from the back to other parts of the body and are responsible for development of the skull and face, along with pigmentation and other traits. The hypothesis suggests domestication pressures lead to fewer neural crest cells reaching their targets, which in turn results in the traits researchers see again and again.

The new raccoon results also emphasize that domestication-related changes do not occur in a vacuum—the research team found that the snouts of urban raccoons in cold climates are shorter than those of their rural counterparts overall, but they may still be longer than the snouts of rural raccoons from hot climates. (Larger body size is considered an adaptation to cold environments.)

Looking at snout changes is just one piece of the domestication puzzle. Lesch hopes to continue this work, potentially by testing genetics and stress hormones across different raccoon populations, she tells Scientific American. According to a statement, her current class is repeating the research to see if the trends hold true for other urban mammals, like armadillos and opossums.

The study was conducted as part of a biometry class at the University of Arkansas at Little Rock and includes 5 graduate and 11 undergraduate students as co-authors.

“I wanted to teach this class in a way that students would have their own data that they collect and analyze,” Lesch says in the statement. “The benefit is that I didn’t have to push students to complete the work. They were intrinsically motivated because they cared.”

For some students, this research offered their first opportunity to contribute to peer-reviewed work.

“This will be my first paper that I have published. It’s very exciting,” Alanis Bradley, an applied biosciences PhD student, says in the statement. “That first foot in the door is very hard to move through, and this class gave me a good understanding of what I need to do in research.”

Marta Hill | Read More

Marta Hill is a science journalist based in New York City and a former intern at Smithsonian magazine. She is a part of the 2025 class of New York University’s Science, Health and Environmental Reporting Program. Her work has appeared in the Transmitter, Eos, Boston.com and more.