I know this is a pretty old thread, but it looks like, to me at least, that whatever past society there was had already selectively bred and grew these animals and plants, and the players are merely just picking up the pieces of what was left? Animals (at least in the version me and my friends play on) really only just de-feralize (idk if that's a real word) and become acquainted with and less afraid of Seraphs (and probably humans too).