I think they’re feral versions of domesticated ones the indigenous Americans had before the small pox plague happened. They’re like rodent-cows, so it makes sense to me. After most of the natives died, a bunch of the capys just went back to being feral, but then people came back pretty quickly & started hunting them again. Well, now we’re back to keeping them, and sometimes eating them. I’m guessing the chillness is something that was bred into them, and we do tend to like chill animals.