New research reveals urban raccoons across the US show early signs of domestication

A smart, adaptable urban raccoon may have a shorter snout – a key physical trait pets and other pets. The new discovery describes what a biologist says may be the first record of domestication in its earliest stages.

For Rafaela Loesch, an assistant professor at the University of Arkansas at Little Rock, inspiration struck while she was walking around campus. She tossed the can into the trash can and it landed not with a clang but with a thud. Soon Lesh understood why the raccoon – also known as the “garbage panda” – stuck his head out of the garbage.

Loesch wondered how common and comfortable raccoons could be in urban environments—even in the middle of the day—and it piqued her curiosity: Could she be witnessing the early stages of the same process that led to the domestication of dogs thousands of years ago?

“That was the first point where I started to wonder if there might be a difference between rural and urban populations, where urban populations were on a trajectory of domestication,” Loesch said.

It's fitting that her epiphany involved trash. Fossil findings suggest that wolves started hanging around people as much as before. 30,000 years agocollecting waste and leftover food. During the period thousands of yearsAround the world, adaptations in the behavior and physical characteristics of wolves have made them suitable for cohabitation with humans. That is, in a word, domestication.

“Trash is actually a stimulant. Everywhere people go, there is trash. Animals love our trash,” Loesch said in a statement. “All they have to do is tolerate our presence, not be aggressive, and then they can feast on everything we throw away. It would be appropriate and fun if our next domesticated species were raccoons.”

To test this idea, Loesch and a team of students examined whether urban raccoons had developed shorter snouts, a known indicator of domestication.

Searching for “domestication syndrome” in raccoons

Naturalist Charles Darwin observed in the 1800s that domesticated animals have several seemingly unrelated physical traits that their wild counterparts do not have. Pets tend to have shorter noses, smaller teeth, floppy ears, curly tails, and white coat patches. A Article 2014 in the journal Genetics. proposed an explanation for the development of this specific set of traits, known as the “domestication syndrome”.

The authors of a 2014 study said that less aggressive and more docile individuals fare better among humans, leading to natural selection toward tameness. This, in turn, appears to influence early embryonic development—specifically, by reducing the number of neural crest cells that migrate throughout the body and go on to form head and facial features, as well as the pigment cells that give fur its color.

“It appears that selection for domestication has created some deficit in these cells that helps us explain all these different traits that we see,” Lesh said.

Lesh decided to focus on one of these characteristics—snout length—to determine whether raccoons living in urban environments and sharing space with people might be different from their rural counterparts.

She and 11 undergraduate and five graduate students in her fall 2024 biometrics class combed through more than 19,000 photographs of raccoons in iNaturalist, an online database of wildlife observations submitted by hobbyists and citizen scientists from across the country. They found 249 images that showed animals in perfect profile.

The researchers then used computer imaging software to measure the length of the individuals' snout from the tip of the nose to the tear duct and the overall length of the head from the tip of the nose to where the ear attaches to the head. When Loesch and her students mapped the county where each photograph was taken, a clear pattern emerged: Urban raccoons had snouts that were 3.6 percent shorter than those of raccoons in rural areas.

“It doesn't sound like a lot, and in some ways it isn't that much, but when you think about the fact that these animals are potentially only in the very early stages of domestication, it's still a pretty clear signal,” Loesch said. She was the lead author of the study, published Oct. 2 in the journal. Frontiers in Zoology.

Or this particular phenotype or trait with a shorter snout could be a signal of something completely different, says zooarchaeologist Kathryn Grossman, an assistant professor of anthropology at North Carolina State University who was not involved in the study. “I don’t know if this is domestication or if it’s a domestication-like phenotype,” she said.

Raccoons vs pets

Raccoons are common in human homes, but Grossman, who studies the remains of ancient civilizations, noted that they differ in some respects from other domesticated species. “Domesticated animals have very specific social structures,” she said, “and raccoons are not one of those animals.”

For example, wild wolves, sheep and cattle live in packs or herds with a clear social hierarchy and are not territorial.

“While these traits certainly matter when it comes to the likelihood of a species becoming domesticated, we also see flexibility in what that might look like,” Loesch said.

According to Lesh, wild cats and wolves have very different social and hierarchical structures. “However, they were both eventually tamed,” she noted. Raccoons may not be pack animals, she added, but they are definitely social.

Loesch next hopes to confirm the findings by analyzing the university's decades-old collection of raccoon skulls. She also wants to compare the behavior of rural and urban raccoon populations.

However, without the ability to travel through time, Lesh will never know if this is truly the beginning of the process of taming these resourceful creatures.

If raccoons are truly on the path to domestication, she said, thousands of years later they might also develop floppy ears, white spots and curly tails. “But I'm encouraged that we can explore this story while it's in its early stages,” she said. “And while we may not see what it will develop into, we can create a record of how it all began.”

Amanda Schupak is a science and health journalist based in New York.

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