@Nimis – Interesting. What I found intriguing is that for me it was almost as if a switch was flipped at the moment my wife gave birth. It wasn’t something that evolved slowly over the course of the pregnancy, and it wasn’t just the smell thing. It seemed there was a whole new circuit that became active. Everyone who entered the room, even those I have known all my life were a “potential threat”, etc…
But getting back to the topic at hand, it’s hard to describe the level of that heightened sense of smell. I could literally smell animals in the woods (I kid the not), but it did seem to be somewhat selective. It took a couple of years to return to normal.
The whole experience made me feel somewhat like a gorilla who still retained his human cerebral cortex. It was rather unsettling.