The discourses themselves function in the same way as physical characteristics in primate hierarchy. Whatever the discourses determine is "best" becomes the strongest/fastest/whatever that determines hierarchical rank. (There's a lot left unsaid here). The power of the discourse determines rank.

Some of our discourses, through us, compete for dominance; they erase, destroy, devalue other discourses, and these discourses view EVERY other discourse as an enemy. Think of religious people trying to erase other religions, political people trying to erase 'the other side,' etc.