Pet rabbits less afraid of people because their brains have shrunk

A new study finds that domesticating rabbits has changed the structure of their brains so that they process fear completely differently to wild ones.

Pet rabbits are less afraid of contacts with humans, thanks to major differences in their brains, revealed advanced imaging scans.

Researchers found alterations in regions involves in their response to fear, the amygdala and medial prefrontal cortex.

Scientists at Uppsalla University in Sweden raised domestic and wild rabbits in similar conditions and used high-resolution MRI scanners to study how domestication affected their brains.

Results showed that domestication has had a major effect, with the amygdala, the area that senses fear, smaller in domestic rabbits.

The part of the brain that controls the animal's response to that fear, the medial prefrontal cortex, was found to be bigger.

Pet rabbits also had less white matter, which limits their information processing abilities, making them slower to react.

In contrast to domestic rabbits, wild rabbits have a very strong flight response.

Due to their history of being are hunted by eagles, hawks, foxes and humans, they must remain alert and reactive to survive in the wild.

Lead researcher and PhD student Irene Brusini said, “We observed three profound differences between the brains of wild and domestic rabbits. Firstly, wild rabbits have a larger brain-to-body size ratio than domestic rabbits. Secondly, domestic rabbits have a reduced amygdala and an enlarged medial prefrontal cortex. Thirdly, we noticed a generalised reduction in white matter structure in domestic rabbits.”

The full findings of the study were published in the journal PNAS.