Just Being Near Humans Causes Animals To Change

By definition, domestication is the process of adapting animals or plants for human need. Naturally, it seems safe to say that people had a hand in domesticating the wild, but research reveals that animals might not have needed humans at all.

A pet mouse photographed in February 2008. New research indicates that mice can domesticate themselves without human interference. MARK RALSTON/AFP/Getty Images

National Geographic explains that domestication is more complex than simply training an animal to be docile toward humans. Rather, the qualities that make animals friendly toward people are bred through several generations of interacting with humans. And the magazine points out that domestication is often assumed to be something humans practiced.

But Swiss researchers found that wild mice were able to domesticate themselves. Published in the Royal Society Open Science on March 7,the team initially sought to study diseases in 12 wild mice that were kept in a barn. However, they began noticing changes in the animals not seen in wild mice, notably white patches of hair and shorter head sizes. The animals were left alone, coming and going at will, but researchers did provide food and water.

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Over the course of 14 years, the sample grew on their own, meaning the team did not breed the animals, reaching a population ranging from 250-430 creatures at any given time. Between 2010 and 2016, the scientists found that white colored patches on the otherwise brown mice doubled. On average, the rodents' heads also grew shorter. Both are signs of domestication.

This study shows that the mice were able to domesticate themselves merely by being in the presence of humans, but without interference from people.

"It's simply from being near us that is likely to have caused these changes," study co-author and evolutionary biologist Anna Lindholm of the University of Zurich in Switzerland, told Science magazine.

Although this self-domestication was only discovered in mice for this study, it opens up the possibility that the phenomenon can be found in other animals, too.