Domestication has shrunk the brains of pet rabbits

The brains of domesticated rabbits are different than those of their wild counterparts, and a new study found that the changes make pet rabbits less fearful of humans and contact.

Researchers from Uppsala University in Sweden conducted a study to compare raised domestic and wild rabbits. The findings were published in the journal PNAS.

Domestic rabbits are able to thrive alongside humans because their amygdala and medial prefrontal cortex, the areas of the brain responsible for fear processing, are distinctively different from wild rabbits.

Both wild and domestic rabbits were used for the study, and the researchers scanned the rabbits’ brains with magnetic resonance imaging to see if domestication had any effect on brain shape and activity.

The researchers found that domestication radically changed the areas in the brain that sense fear and the amygdala was smaller compared to the scans of the wild rabbits.

The domesticated rabbits also had larger medial prefrontal cortices, which is the area controls an animal’s response to fear.

These changes make sense because domestic rabbits must learn to interact with humans who provide food and shelter, whereas wild rabbits need to keep on high alert to avoid predators.

Domestic rabbits were also slower to react due to less white matter in their brain.

“In a previous study we reported that genetic differences between wild and domestic rabbits are particularly common in the vicinity of genes expressed during brain development,” said Miguel Carneiro, a leading author of the paper. “In the present study, we decided to use high-resolution MRI to explore if these genetic changes are associated with changes in brain morphology.”

The study sheds insight on how the process of domestication over time can change an animal’s brain shape and inherent evolutionary survival instincts.

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By Kay Vandette, Earth.com Staff Writer