Human trash is ‘kick-starting’ the domestication of city-dwelling raccoons, study suggests
Urban raccoons are showing the first signs of domestication, according to a new study.
Using photos uploaded to the citizen science platform iNaturalist, researchers found that raccoons in urban environments had shorter snouts than their rural counterparts. The difference could be one of several traits that make up “domestication syndrome,” the scientists wrote in a study published Oct. 2 in the journal Frontiers in zoology.
“I wanted to know if living in an urban environment would restart domestication processes in animals that are currently not domesticated,” study co-author Raffaela Leschzoologist at the University of Arkansas Little Rock, said in a statement. “Could raccoons be on the path to domestication simply by hanging around near humans?”
Domestication begins when animals adapt to a new niche created by the presence of humans. For raccoons, this niche might involve rummaging through our trash.
“Trash is really the kickstarter,” Lesch said. This waste makes an easy meal for the creatures. “All they have to do is put up with our presence, not be aggressive, and then they can feast on whatever we throw away.”
In the new study, Lesch and a team of 16 students looked for early signs of domestication in raccoons in the United States. Physical signs that a species is being domesticated often include a shorter snout, drooping ears, white spots, and a reduced fear response – a series of traits collectively called “domestication syndrome.”
Taken from nearly 20,000 photos uploaded to iNaturalistthe team found that the snouts of raccoons living in densely populated areas were about 3.5 percent shorter than those of raccoons in more rural counties.
These seemingly unrelated “domestication syndrome” traits tend to appear early in domestication and may be linked through mutations that occur during an animal’s development. In 2014, scientists proposed that mutations in neural crest cellsa type of stem cell that forms in vertebrate embryos, could cause these changes.
The new results appear to support this hypothesis, the researchers wrote in the study. A reduced fear response helps animals like raccoons take advantage of human environments. Natural selection could therefore make this courage more common in urban environments. Changes in snout length during early domestication could suggest that the two traits are linked, the team said.
Future studies will examine whether the same pattern applies to other urban mammals, such as opossums, according to the release.
“This will help us know if human presence is enough to already start the domestication process of a species,” Lesch said.
