There is actually a different kind of human that has lived in the depths of the amazons. They look the way that Neanderthals would look and their intelligence is lower than that of regular human beings. Their evolution has stopped because they have not been exposed to any evaluative behavior. They only exercise their minds to hunt, gather and procreate. They have no debates or languages and they grunt to each other with different kinds of sounds and volumes to communicate how they feel.
They have been taken to a section of the jungle that is close to the werewolves camp. They are not smart enough to know how to get through a few important obstacles that don’t allow access to the werewolf territory.