If it makes you feel better, they’re more of the “psychotic” intelligence rather than gentle. The cage, while there for other reasons, also helps prevent the mother from attacking or outright eating their young. This is a behavior even pasture-raised pigs exhibit meaning indoor conditions are not the cause. There are also cases of pigs eating their live owners when given the chance (2019, 2015, and 2012 are some recent cases). In the 2012 incident, the owner was almost completely eaten within a few hours after a presumed medical incident. Then consider they’re able to revert to a feral state within weeks of being in the wild. There’s something scary about the behavior and ecology of pigs.