PNAS 115, 7380–7385 (2018)

Domesticated animals tend to be tamer than their wild counterparts. The rabbit was domesticated relatively recently compared to other animals, and there are considerable behavioral differences between rabbits that are accustomed to humans and those that are not. The difference could be all in their heads.

An international team of researchers previously sequenced the genomes of wild and domesticated rabbits and observed changes in areas involved in brain development. They recently explored if those genetic differences resulted in morphological differences too. They gave eight tame and eight wild rabbits from Spain postmortem MRIs. The domestic rabbits had smaller brains relative to their body size compared to wild animals, with smaller amygdala but larger medial prefrontal cortex volumes. The former responds to fear, while the latter tempers responses to negative experiences. These changes support the notion that domesticated animals have indeed lost some of their innate fear of man.