Raccoons Are Showing Signs Of Domestication In CA, Study Says

Raccoons may be evolving in real time — adapting to life alongside humans in ways that echo the early domestication of dogs and cats, according to new study.

A new peer-reviewed study found that raccoons living in California cities have noticeably shorter snouts than their rural counterparts, a physical shift scientists say resembles early signs of domestication.

Raccoons, with their dexterous paws and bandit-like masks, have long been known for pilfering trash. The study’s authors say easy access to human garbage may be pushing the animals to grow more comfortable around people.

“One thing about us humans is that, wherever we go, we produce a lot of trash,” the study’s co-author and University of Arkansas at Little Rock biologist Raffaela Lesch, told Scientific American. "If you have an animal that lives close to humans, you have to be well-behaved enough."

Before dogs were domesticated, they scavenged around human trash piles, while cats were drawn to the mice that gathered near waste. Over time, both species became less fearful of people and passed those tamer traits to their offspring.

But domestication doesn't end with demeanor.

The study, published this month in Frontiers in Zoology, analyzed nearly 20,000 user-submitted raccoon photos from iNaturalist, a platform developed at UC Berkeley.

"Quite a bit" of the contributed images of raccoons in the national study were taken in California cities, according to Arya Natarajan of iNaturalist.

“We’re really trying to encourage people to take photos and share their observations of even what they might consider as the common things that they see,” she told SFGATE. “Because clearly we’re still learning a lot about even the most ‘common things,’ like raccoons, you know, that you see all over the place.”

Researchers analyzing the photographs found that raccoons living in cities had snouts about 3.5 percent shorter relative to skull size than those in rural areas, even after controlling for climate and geography.

Scientists say the difference is small but significant — and consistent with “domestication syndrome,” the suite of traits that often emerges when animals adapt to life near humans.

“Urban environments create different selection pressures,” the authors wrote. “Tolerance of humans, access to human refuse and reduced fear may favor individuals with certain morphological traits.”

Lesch told Scientific American that he'd like dive deeper into studying raccoons and the different stress hormones between urban and rural creatures.

“I’d love to take those next steps and see if our trash pandas in our backyard are really friendlier than those out in the countryside,” she told Scientific American.