So why rotten meat smells terrible and a steak delicious? Why would we evolve that perception of something that nutritious and which could prevent me from starving. Why my nose keeps telling me to keep away from rotten meant?
If the appropriate "paleo diet" bacteria settled in (e.g. using the gradual method to build tolerance), your nose would probably change its mind soon enough.
Not a biologist, just a layman here.
+1. Given the recent research on the gut-brain axis, I too believe that this mechanism is the case.