Trash Pandas on the Path to Domestication: Urban Raccoons Show Physical and Behavioral Shifts

Urban raccoons may be showing the first signs of domestication

Raccoons—nimble, masked and common around North American neighborhoods—are adapting physically to life around people, a new study finds. Researchers analyzed nearly 20,000 community-science photos and report that raccoons living in urban areas have snouts about 3.5% shorter than their rural counterparts, a small but consistent difference that could signal early stages of domestication.

The authors challenge the popular idea that domestication begins only when humans capture and breed wild animals. Instead, they argue the process often starts earlier: wild species that habituate to human environments and exploit abundant resources such as food waste experience selection for traits that favor living near people.

“One thing about us humans is that, wherever we go, we produce a lot of trash,”

says Raffaela Lesch, a biologist at the University of Arkansas at Little Rock and co-author of the study. She notes that scavenging around human refuse rewards animals that are bold enough to approach but not so aggressive as to threaten people.

“If you have an animal that lives close to humans, you have to be well-behaved enough. That selection pressure is quite intense.”

Researchers connect these behavioral shifts to a suite of physical traits—shorter faces, smaller heads, floppy ears and patches of white fur—long observed in domesticated species and collectively known as "domestication syndrome." A prominent explanation, proposed in 2014, links these traits to changes in neural crest cells, embryonic cells that migrate to many body parts during development. Mutations that reduce neural crest cell proliferation or migration could plausibly produce both calmer behavior and the associated physical changes.

For this study, Lesch and 16 students collected almost 20,000 raccoon photographs from iNaturalist across the contiguous United States and measured facial proportions. The team found a consistent ~3.5% shortening of the snout in urban raccoons, a pattern that echoes observations in urban foxes and mice. Adam Wilkins, who originally proposed the neural crest-cell explanation, says the new findings are consistent with animals becoming "a little bit less afraid" near people and possibly showing early domestication traits.

The authors emphasize that the work is an early step and does not yet prove causation. Photo-based measurements can be influenced by sampling or photographic bias, and morphological differences could reflect environmental plasticity as well as genetic change. Lesch says logical next steps include trapping animals to compare genetics and stress-hormone profiles between urban and rural populations, and testing whether similar trends appear in other synanthropic species such as opossums and armadillos.

“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,” Lesch says, underscoring both the curiosity and the caution driving future work.