A study released last month verified that there is a clear reduction in feline brain size relative to their wild relatives. This research replicates research done in 1969 and 1972, and provides more evidence that domestication has had a significant impact on feline physiology.
Some theories for this include that there exists “a trade-off between the relative importance of the energetic needs of the brain and other organ systems, such as the gut and/or reproductive system,” implying that the physiological cerebral requirements of house cats are less demanding than those in the wild. Another is that domestication has caused timing differences in development, leading to different physiological outcomes. Worth noting is that feralization, i.e. the process of becoming feral or wild, of domesticated animals does not reverse this process either, even after multiple generations, suggesting that the changes are long-term and evolutionary in nature.
Source:
https://royalsocietypublishing.org/doi/10.1098/rsos.210477