system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: Why do we stop smelling things after being exposed to them for a while?

Edit: Thanks everyone for the replies! Really appreciate y'all takin the time, fascinating stuff.
gpt
The brain filters out everything that doesn't change, everything that is "expected". This way it can concentrate on the new things that are happening, things that (usually) are much more important.

It does the same thing for sights and sounds.