Adventure mode is, in a way turn based. You see, try standing still for a moment in adventure mode, notice how nothing moves. Then move and notice how everything else moves. This is really useful to plan out strategies in the middle of battle.
I don't mean to be rude but... no shit.
A less rude and more snarky response would be:
Adventure mode is a roguelike.
Companions will always attack wildlife, hostile or not. Unless you like losing your companions (not getting them killed, but literally having them get lost) and having the archers waste all their ammo, fast (T)ravel out of the area after accomplishing your main objective if there's copious wildlife present.
This AI quirk doesn't only affect your companions, though. If you're hopelessly outnumbered and need to run away, look for a herd of animals. If your character is fast enough to outrun the animals you can just cut right through the herd, but if you're slower it may take some careful circling around. Either way, try to get those animals closer to your attackers than to you. You can safely make your getaway once that goblin ambush party is distracted and decides to go hunt warthogs instead.
Another way to get attackers off your trail is to set fires. Most enemies won't be stupid enough to just sit there and burn to death (unless you also stay dangerously close to the fire), but the smoke will obscure their vision. This is even more effective at nighttime.