@kaia currently mostly reading rudy rucker short stories, but i started a book called 'the emperor of scent', which is about a scientist who tries to find out who the sense of smell works.

i didn't even know that was much of a questions, but it is, because smell seems to be doing something that's impossible: detect any kind of molecule, instantly.

for comparison, the digestive system detects (and digests) some molecules instantly, but can't adapt very much (you can never eat grass).

and the immune system can detect (and destroy) most molecules, but it takes time (you get a flu first).

but the sense of smell can detect any molecule in a certain size range, without ever having seen it, either in the lifetime of the person or in evolutionary history.