Domestication has caused cat brains to shrink.
"Our data indicates that domestic cats indeed, have smaller cranial volumes (implying smaller brains) relative to both European wildcats (Felis silvestris) and the wild ancestors of domestic cats, the African wildcats (Felis lybica), verifying older results," state the authors of a new paper published in the January 2022 issue of Royal Society Open Science.
From Science Alert:
Cat brain size is something that researchers have been looking into since the 1960s and 1970s, and this trend of smaller brains appearing in domesticated animals has also been observed in sheep, dogs, and rabbits. It certainly seems that something significant is going on here.
The researchers put forward an existing idea that natural selection for tameness in domestication leads to the production of fewer neural crest cells in the animals (linked to excitability and fear). That in turn could feasibly lead to changes in stress response, brain size, and overall body morphology.