Urban Trash May Be Kick‑Starting the Domestication of Raccoons, Study Finds

City-dwelling raccoons are exhibiting early physical changes consistent with the beginnings of domestication, researchers report. A new analysis of community-submitted photos suggests urban raccoons have slightly shorter snouts than their rural counterparts — a change that may be linked to behavioral shifts that help them thrive around people.

What the study did

The research team, led by zoologist Raffaela Lesch of the University of Arkansas Little Rock and involving 16 students, examined nearly 20,000 photographs uploaded to the citizen science platform iNaturalist. They measured facial proportions and compared raccoons from densely populated counties with those from more rural areas. The work was published Oct. 2 in the journal Frontiers in Zoology.

Main findings

Raccoons living in urban counties were found to have snouts about 3.5% shorter on average than raccoons from rural counties. The authors suggest this modest but measurable difference could represent one of the early physical markers of domestication syndrome — a cluster of traits that sometimes appears when wild animals adapt to life near humans.

Why it matters

Domestication syndrome commonly includes features such as shorter snouts, floppy ears, white markings and a reduced fear or aggression toward people. These traits often surface together during the early stages of domestication, and one hypothesis is that changes in neural crest cells — embryonic cells that influence development across many tissues — may produce multiple, linked changes in anatomy and behavior.

"Trash is really the kickstarter," said co-author Raffaela Lesch, referring to easily available discarded food in cities that encourages raccoons to tolerate human presence and exploit new resources.

The researchers argue that a reduced fear response would allow raccoons to take advantage of human environments, and that developmental changes associated with snout length could accompany behavioral shifts. The study does not claim that raccoons are domesticated now, but rather that urban living could be initiating the early stages of that process.

Next steps

The team plans to investigate whether similar patterns appear in other urban mammals, such as opossums. If the pattern repeats across species, it would strengthen the case that persistent human presence and easy access to anthropogenic food sources can begin to shape both behavior and morphology in wild animals.

Note: Findings are based on photographic measurements and population-level comparisons; further research combining genetics, behavior and long-term monitoring will be needed to confirm whether these changes reflect evolutionary shifts toward domestication.