[Wild is not really wild: brain weight of wild domestic mammals]

Domestication leads to the reduction of brain weight, decreases reach from 8.1% in laboratory rats up to 33.6% in domesticated pigs. The question is: Do brain weights increase by feralization? We compared the brain weights of domesticated mammals (cat, dog, pig, goat, ass) with their feral forms. In none of the cases studied, brain weight is increased in wild domestic mammals. So, feral mammals do not return back to the status of their wild species.